Politics, latent and overt, in Hill of Fools
- Authors: Wright, Laurence
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:7064 , http://hdl.handle.net/10962/d1007430
- Description: [From the text]: R. L. Peteni’s novel Hill of Fools (1976) is a work that benefits greatly when Collingwood’s maxim is observed. The author’s family history and the circumstances surrounding the book’s publication add a dimension of political and social meaning which its surface deliberately occludes. Perhaps more importantly, while the story can readily be enjoyed, the quality of sensibility behind the work is not readily accessed without understanding some of the socio-political background.
- Full Text:
- Date Issued: 2004
- Authors: Wright, Laurence
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:7064 , http://hdl.handle.net/10962/d1007430
- Description: [From the text]: R. L. Peteni’s novel Hill of Fools (1976) is a work that benefits greatly when Collingwood’s maxim is observed. The author’s family history and the circumstances surrounding the book’s publication add a dimension of political and social meaning which its surface deliberately occludes. Perhaps more importantly, while the story can readily be enjoyed, the quality of sensibility behind the work is not readily accessed without understanding some of the socio-political background.
- Full Text:
- Date Issued: 2004
Pollination biology of Bergeranthus multiceps (Aizoaceae) with preliminary observations of repeated flower opening and closure
- Peter, Craig I, Dold, Anthony P, Barker, Nigel P, Ripley, Bradford S
- Authors: Peter, Craig I , Dold, Anthony P , Barker, Nigel P , Ripley, Bradford S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6529 , http://hdl.handle.net/10962/d1005970
- Description: Little is known about pollination of the Aizoaceae (Mesembryanthemaceae). There are sparse reports of generalist pollination in the family by a variety of insects (predominantly bees). Furthermore, most species are self-incompatible in cultivation. In this study, observations were made on two populations of Bergeranthus multiceps (Salm-Dyck) Schwantes growing in the Eastern Cape province of South Africa. Insects visiting the flowers were collected and examined for pollen. While 79 individual insects (in 24 genera representing 14 families and four orders) were collected visiting the flowers, the majority (43 individuals) were female Allodapula variegata bees (Apidae, subfamily Xylocopinae, tribe Allodapini)collecting pollen. All other bee visitors were also female, suggesting pollen collection as the primary activity at the flowers. The protandrous flowers were found to be self-incompatible, pointing to the importance of bee-mediated xenogamy in this species. The flowers of B. multiceps are bright yellow in the human visual spectrum. In addition, the petals of this species reflect ultraviolet light. In contrast, the yellow anthers absorb UV. Flower opening and closing is common in the Aizoaceae. Interestingly, in B. multiceps flowers open at about 15:30 and remain open for approximately three hours before closing again in the late afternoon. These afternoon flower opening events were found to be closely correlated to ambient temperatures above 23°C, relative humidity lower than 50% and vapour pressure deficit below 1.05 kPa measured from as early as 09:00 on the days when flowers opened.
- Full Text:
- Date Issued: 2004
- Authors: Peter, Craig I , Dold, Anthony P , Barker, Nigel P , Ripley, Bradford S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6529 , http://hdl.handle.net/10962/d1005970
- Description: Little is known about pollination of the Aizoaceae (Mesembryanthemaceae). There are sparse reports of generalist pollination in the family by a variety of insects (predominantly bees). Furthermore, most species are self-incompatible in cultivation. In this study, observations were made on two populations of Bergeranthus multiceps (Salm-Dyck) Schwantes growing in the Eastern Cape province of South Africa. Insects visiting the flowers were collected and examined for pollen. While 79 individual insects (in 24 genera representing 14 families and four orders) were collected visiting the flowers, the majority (43 individuals) were female Allodapula variegata bees (Apidae, subfamily Xylocopinae, tribe Allodapini)collecting pollen. All other bee visitors were also female, suggesting pollen collection as the primary activity at the flowers. The protandrous flowers were found to be self-incompatible, pointing to the importance of bee-mediated xenogamy in this species. The flowers of B. multiceps are bright yellow in the human visual spectrum. In addition, the petals of this species reflect ultraviolet light. In contrast, the yellow anthers absorb UV. Flower opening and closing is common in the Aizoaceae. Interestingly, in B. multiceps flowers open at about 15:30 and remain open for approximately three hours before closing again in the late afternoon. These afternoon flower opening events were found to be closely correlated to ambient temperatures above 23°C, relative humidity lower than 50% and vapour pressure deficit below 1.05 kPa measured from as early as 09:00 on the days when flowers opened.
- Full Text:
- Date Issued: 2004
Praxis-based assignments for professional development in the Rhodes University/Swaziland Participatory Course in Environmental Education : the case of assignment four
- Authors: Motsa, Elizabeth Matfobhi
- Date: 2004
- Subjects: Rhodes University / Swaziland Participatory Course in Environmental Education Environmental education -- Swaziland Environmental education -- Study and teaching -- Swaziland
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1710 , http://hdl.handle.net/10962/d1003593
- Description: The aim of this study was to find out how praxis is fostered in professional development processes, through the assignment four of the Rhodes University / Swaziland Participatory course in Environmental Education (referred to as the Swaziland course), in the Swaziland context. The research aimed at exploring instances of praxis in assignment four development processes and in implementing the assignment ‘product’ in the field of participants’ practice at their schools. The research is intended to improve practice in professional development in the Swaziland course, and in the SADC region more broadly, although the case study does not assume generalisability. The study employed a naturalistic research methodology, involving the development of an interpretive case study to aid understanding of social phenomena in the natural setting. It is influenced by the belief that knowledge is socially constructed and the assumption that meanings are generated and shared through language. The research methods involved observing interactions in the course processes during tutorials sessions and I compiled a course processes profile. I also analyzed copies of assignment four products of two course participants, and observed them using their assignment ‘products’ in their workplaces. Using this data, I generated two ‘constructions’ of the two course participants’ experiences of praxis-based assignment work in the Swaziland course. I also interviewed two course tutors. Data was analysed with an intention to understand actions and interactions relating to praxis-based assignment work. Two ‘layers’ of data analysis were undertaken, to deepen understanding of the phenomenon studied. Through this research I have learnt that though assignment processes enable praxis basedlearning, there are problems encountered in participants’ field of practice due to power relations and participants articulation of the relationship between theory and practice. These, and other structural factors impinge on reflexive agency in the context of both educational and environmental praxis. The structures in the school system frustrate reflexive agency in environmental teaching and learning, and socio-political and socio-economic structures also constrain environmental praxis, hence false consciousness prevails. Given the above situation I recommend further research into the relationship between environmental and educational praxis in environmental education and further research into reflexive agency in environmental education contexts.
- Full Text:
- Date Issued: 2004
- Authors: Motsa, Elizabeth Matfobhi
- Date: 2004
- Subjects: Rhodes University / Swaziland Participatory Course in Environmental Education Environmental education -- Swaziland Environmental education -- Study and teaching -- Swaziland
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1710 , http://hdl.handle.net/10962/d1003593
- Description: The aim of this study was to find out how praxis is fostered in professional development processes, through the assignment four of the Rhodes University / Swaziland Participatory course in Environmental Education (referred to as the Swaziland course), in the Swaziland context. The research aimed at exploring instances of praxis in assignment four development processes and in implementing the assignment ‘product’ in the field of participants’ practice at their schools. The research is intended to improve practice in professional development in the Swaziland course, and in the SADC region more broadly, although the case study does not assume generalisability. The study employed a naturalistic research methodology, involving the development of an interpretive case study to aid understanding of social phenomena in the natural setting. It is influenced by the belief that knowledge is socially constructed and the assumption that meanings are generated and shared through language. The research methods involved observing interactions in the course processes during tutorials sessions and I compiled a course processes profile. I also analyzed copies of assignment four products of two course participants, and observed them using their assignment ‘products’ in their workplaces. Using this data, I generated two ‘constructions’ of the two course participants’ experiences of praxis-based assignment work in the Swaziland course. I also interviewed two course tutors. Data was analysed with an intention to understand actions and interactions relating to praxis-based assignment work. Two ‘layers’ of data analysis were undertaken, to deepen understanding of the phenomenon studied. Through this research I have learnt that though assignment processes enable praxis basedlearning, there are problems encountered in participants’ field of practice due to power relations and participants articulation of the relationship between theory and practice. These, and other structural factors impinge on reflexive agency in the context of both educational and environmental praxis. The structures in the school system frustrate reflexive agency in environmental teaching and learning, and socio-political and socio-economic structures also constrain environmental praxis, hence false consciousness prevails. Given the above situation I recommend further research into the relationship between environmental and educational praxis in environmental education and further research into reflexive agency in environmental education contexts.
- Full Text:
- Date Issued: 2004
Pre-emigration reflections : Afrikaans speakers moving to New Zealand
- De Klerk, Vivian A, Barkhuizen, Gary P
- Authors: De Klerk, Vivian A , Barkhuizen, Gary P
- Date: 2004
- Language: English
- Type: Article , text
- Identifier: vital:6138 , http://hdl.handle.net/10962/d1011590
- Description: This article reports on the pre-emigration reflections of 15 Afrikaans speakers, all of whom were in the final stages of preparing to emigrate to New Zealand. The study explores the linguistic histories of the participants, their attitudes to their mother tongue (Afrikaans) and to English, and their views on South Africa's language policy and how it has influenced their decisions to leave the country. The paper also offers a view on possible long-term linguistic outcomes for these families.
- Full Text:
- Date Issued: 2004
- Authors: De Klerk, Vivian A , Barkhuizen, Gary P
- Date: 2004
- Language: English
- Type: Article , text
- Identifier: vital:6138 , http://hdl.handle.net/10962/d1011590
- Description: This article reports on the pre-emigration reflections of 15 Afrikaans speakers, all of whom were in the final stages of preparing to emigrate to New Zealand. The study explores the linguistic histories of the participants, their attitudes to their mother tongue (Afrikaans) and to English, and their views on South Africa's language policy and how it has influenced their decisions to leave the country. The paper also offers a view on possible long-term linguistic outcomes for these families.
- Full Text:
- Date Issued: 2004
Price discovery, price behaviour, and efficiency of selected grain commodities traded on the agricultural products division of the JSE securities exchange
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
Probing learners' conceptual understanding of oxidation and reduction (redox) reactions : a case study
- Authors: Addam, Billey Bright
- Date: 2004
- Subjects: Competency based education -- South Africa Oxidation-reduction reaction -- Study and teaching Science -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1409 , http://hdl.handle.net/10962/d1002950
- Description: The new political dispensation in South Africa has seen a lot of changes taking place. The democratic wind, which has been blowing in all spheres of the political arena, could not leave out Education. This has led to the transformation in education and the revision of the curriculum guided by the Outcomes-Based Education philosophy (OBE). Thus, require education authorities as well as educators to look at education more comprehensively. The challenge posed to educators now is to develop tools and strategies that will make learning accessible to as many learners as possible and to teach for understanding and construction of knowledge. The principal objective of this study was to investigate the important role the learner's prior knowledge plays and the use of different tools and strategies in stimulating conceptual understanding and construction of knowledge of redox reactions. This was done using learners' own investigations, practical activities, teaching settings and a workshop. The findings show that the learners lacked organized and structured prior knowledge. Learners could not integrate prior experience with new experience. The main issue seems to be the failure of learners to relate classroom experience to everyday redox phenomena. Possible reasons are discussed with some implications for teaching redox. The study further postulates that to assist learners to develop conceptual understanding of redox reactions, different tools and strategies should be employed and teaching made relevant to real-life situations. In so doing, redox concepts would not be abstract to learners.
- Full Text:
- Date Issued: 2004
- Authors: Addam, Billey Bright
- Date: 2004
- Subjects: Competency based education -- South Africa Oxidation-reduction reaction -- Study and teaching Science -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1409 , http://hdl.handle.net/10962/d1002950
- Description: The new political dispensation in South Africa has seen a lot of changes taking place. The democratic wind, which has been blowing in all spheres of the political arena, could not leave out Education. This has led to the transformation in education and the revision of the curriculum guided by the Outcomes-Based Education philosophy (OBE). Thus, require education authorities as well as educators to look at education more comprehensively. The challenge posed to educators now is to develop tools and strategies that will make learning accessible to as many learners as possible and to teach for understanding and construction of knowledge. The principal objective of this study was to investigate the important role the learner's prior knowledge plays and the use of different tools and strategies in stimulating conceptual understanding and construction of knowledge of redox reactions. This was done using learners' own investigations, practical activities, teaching settings and a workshop. The findings show that the learners lacked organized and structured prior knowledge. Learners could not integrate prior experience with new experience. The main issue seems to be the failure of learners to relate classroom experience to everyday redox phenomena. Possible reasons are discussed with some implications for teaching redox. The study further postulates that to assist learners to develop conceptual understanding of redox reactions, different tools and strategies should be employed and teaching made relevant to real-life situations. In so doing, redox concepts would not be abstract to learners.
- Full Text:
- Date Issued: 2004
Processes that influence the experiences of children living with mothers that have HIV: two case studies
- Authors: Castelletto, Simona
- Date: 2004
- Subjects: AIDS (Disease) in women , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Mothers and daughters -- Social aspects , Mothers and sons -- Social aspects , AIDS (Disease) in children -- Social aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3166 , http://hdl.handle.net/10962/d1007728 , AIDS (Disease) in women , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Mothers and daughters -- Social aspects , Mothers and sons -- Social aspects , AIDS (Disease) in children -- Social aspects -- South Africa
- Description: Maternal HIV-infection is considered to be a threat to the psychosocial development of AIDS-affected children. In South Africa, AIDS-affected children may be particularly vulnerable due to the unprecedented effects of the HIV/AIDS epidemic on the breakdown of family and community resources in already disadvantaged communities. The aim of this study was to explore the contextualised experiences of two children living with mothers who have HIV by conducting two case studies. Mother-child dyads were recruited from local HIV/AIDS centres and informed consent was obtained. The mothers were in the minor symptomatic phase of HIV-infection and the children were uninfected and aged between 10 and 12 years. Through semi-structured interviewing, the mothers provided background and contextual information about the children. Play techniques were used in the child interviews to encourage the introduction and exploration of issues salient to the children. Play facilitated engagement around sensitive and potentially anxiety-provoking material. A key issue for the children was their concerns about the anticipated deaths of their mothers. The children held misconceptions about the transmission of HIV/ AIDS. They feared HIV/AIDS and expected that others would have negative perceptions of them. Family processes such as secrecy and avoidance around HIV/AIDS-related issues were understood to perpetuate the children's fears and false beliefs in a broader community context that stigmatised HIV/AIDS. It was argued that the mothers' shame over HIV-infection and their need to protect their relationship with their children compromised their ability to communicate openly with their children and to offer them meaningful emotional support. Limited parental involvement was identified as the key contextual process that engendered vulnerability in the children, as they were isolated within and beyond the family. Recommendations to address the processes that engendered vulnerability in the children are discussed.
- Full Text:
- Date Issued: 2004
- Authors: Castelletto, Simona
- Date: 2004
- Subjects: AIDS (Disease) in women , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Mothers and daughters -- Social aspects , Mothers and sons -- Social aspects , AIDS (Disease) in children -- Social aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3166 , http://hdl.handle.net/10962/d1007728 , AIDS (Disease) in women , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Mothers and daughters -- Social aspects , Mothers and sons -- Social aspects , AIDS (Disease) in children -- Social aspects -- South Africa
- Description: Maternal HIV-infection is considered to be a threat to the psychosocial development of AIDS-affected children. In South Africa, AIDS-affected children may be particularly vulnerable due to the unprecedented effects of the HIV/AIDS epidemic on the breakdown of family and community resources in already disadvantaged communities. The aim of this study was to explore the contextualised experiences of two children living with mothers who have HIV by conducting two case studies. Mother-child dyads were recruited from local HIV/AIDS centres and informed consent was obtained. The mothers were in the minor symptomatic phase of HIV-infection and the children were uninfected and aged between 10 and 12 years. Through semi-structured interviewing, the mothers provided background and contextual information about the children. Play techniques were used in the child interviews to encourage the introduction and exploration of issues salient to the children. Play facilitated engagement around sensitive and potentially anxiety-provoking material. A key issue for the children was their concerns about the anticipated deaths of their mothers. The children held misconceptions about the transmission of HIV/ AIDS. They feared HIV/AIDS and expected that others would have negative perceptions of them. Family processes such as secrecy and avoidance around HIV/AIDS-related issues were understood to perpetuate the children's fears and false beliefs in a broader community context that stigmatised HIV/AIDS. It was argued that the mothers' shame over HIV-infection and their need to protect their relationship with their children compromised their ability to communicate openly with their children and to offer them meaningful emotional support. Limited parental involvement was identified as the key contextual process that engendered vulnerability in the children, as they were isolated within and beyond the family. Recommendations to address the processes that engendered vulnerability in the children are discussed.
- Full Text:
- Date Issued: 2004
Promoting learners' conceptual understanding of electrostatics through use of practical activities in conjunction with prior knowledge of lightning : a case study
- Authors: Maselwa, Matole Reuben
- Date: 2004
- Subjects: Electrostatics -- Study and teaching -- Case studies Science -- Study and teaching -- Case studies Lightning -- Study and teaching -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1717 , http://hdl.handle.net/10962/d1003600
- Description: The research presented in this thesis is situated within an interpretivist paradigm. Within this paradigm, a qualitative case-study research approach was adopted. This seemed most appropriate in my research project since the main focus is on elicitation of prior knowledge and incorporation of such knowledge into 'hands-on' and 'minds-on' practical activities with a view to improving conceptual development. For the purposes of this research project, I designed an interactive teaching and learning unit in electrostatics as an attempt to put into practice a learner-centred approach. This approach, in my view, is in line with the new curriculum in South Africa. The emerging central theme of this thesis is the notion of active participation by learners during teaching and learning. This study was carried out over a period of two years and involved my grade 9 learners, who participated voluntarily. The research process documented in this thesis has been conceptualised into two phases. Phase one was concerned with the elicitation of learners' prior knowledge around lightning. In phase two, learners were engaged in 'hands-on' and 'minds-on' practical activities, and key concepts were identified to ensure conceptual development. The data was collected using a variety of data collection tools, namely: focus group interviews, follow-up whole-class semi-structured interviews, worksheets, videotaped lessons and photographs. The analysis of data revealed that learners come to class with prior knowledge concerning lightning. Within this prior knowledge it was found that there were both ‘scientific’ and ‘non-scientific’ concepts. The identification of key concepts during practical activities was found to be very useful in promoting learning. However, the incorporation of prior knowledge into practical activities posed a challenge and needs further research. iv This research study also highlights some insights into some of the complexities of elicitation and incorporation of learners' prior knowledge, and conceptual development in science classrooms. It also demonstrates the challenges and possibilities during teaching and learning as well as the realities of the demands of the new curriculum and OBE in South Africa, in particular, in historically disadvantaged schools
- Full Text:
- Date Issued: 2004
- Authors: Maselwa, Matole Reuben
- Date: 2004
- Subjects: Electrostatics -- Study and teaching -- Case studies Science -- Study and teaching -- Case studies Lightning -- Study and teaching -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1717 , http://hdl.handle.net/10962/d1003600
- Description: The research presented in this thesis is situated within an interpretivist paradigm. Within this paradigm, a qualitative case-study research approach was adopted. This seemed most appropriate in my research project since the main focus is on elicitation of prior knowledge and incorporation of such knowledge into 'hands-on' and 'minds-on' practical activities with a view to improving conceptual development. For the purposes of this research project, I designed an interactive teaching and learning unit in electrostatics as an attempt to put into practice a learner-centred approach. This approach, in my view, is in line with the new curriculum in South Africa. The emerging central theme of this thesis is the notion of active participation by learners during teaching and learning. This study was carried out over a period of two years and involved my grade 9 learners, who participated voluntarily. The research process documented in this thesis has been conceptualised into two phases. Phase one was concerned with the elicitation of learners' prior knowledge around lightning. In phase two, learners were engaged in 'hands-on' and 'minds-on' practical activities, and key concepts were identified to ensure conceptual development. The data was collected using a variety of data collection tools, namely: focus group interviews, follow-up whole-class semi-structured interviews, worksheets, videotaped lessons and photographs. The analysis of data revealed that learners come to class with prior knowledge concerning lightning. Within this prior knowledge it was found that there were both ‘scientific’ and ‘non-scientific’ concepts. The identification of key concepts during practical activities was found to be very useful in promoting learning. However, the incorporation of prior knowledge into practical activities posed a challenge and needs further research. iv This research study also highlights some insights into some of the complexities of elicitation and incorporation of learners' prior knowledge, and conceptual development in science classrooms. It also demonstrates the challenges and possibilities during teaching and learning as well as the realities of the demands of the new curriculum and OBE in South Africa, in particular, in historically disadvantaged schools
- Full Text:
- Date Issued: 2004
Protecting depositors and promoting financial stability in South Africa : is there a case for the introduction of deposit insurance?
- Authors: Ngaujake, Uahatjiri
- Date: 2004
- Subjects: Banks and banking -- South Africa , Bank deposits -- South Africa , Bank failures , Banks and banking -- State supervision , Deposit insurance , Consumer protection -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1025 , http://hdl.handle.net/10962/d1002760 , Banks and banking -- South Africa , Bank deposits -- South Africa , Bank failures , Banks and banking -- State supervision , Deposit insurance , Consumer protection -- South Africa
- Description: Banks play a pivotal role in economic growth and development of all countries and therefore the stability of the banking system is a vital goal of bank supervisors. Banks act as delegated monitors of depositors’ funds and this relationship, like all principal-agent relationships, presents agency problems. In the case of banks agency problems arise because depositors cannot accurately assess the financial health of banks due to the asymmetry of information existing between banks and depositors. Because banks possess private information on their borrowers, which depositors cannot access, it exposes depositors to risk of loss of deposits in cases of bank failures originating from nonrepayment of such loans. This asymmetry of information also exposes banks to runs by depositors and these runs can lead to bank failures with devastating effects for the financial system and the economy at large. It is for this reason that banks are regulated and supervised more than other institutions. Bank failures are a worldwide phenomenon and South Africa is no exception as evidenced by historical and recent bank failures in South Africa. This thesis investigates the desirability of introducing an explicit deposit insurance scheme in South Africa as a means of protecting small, unsophisticated depositors who are almost always the losers when banks fail, and promoting financial stability. The study finds that bank failures in South Africa are mainly attributable to mismanagement of banks, liquidity problems and fraud. Bank failures as a result of the aforementioned reasons have led to depositors losing their deposits in South Africa. The absence of a clearly defined depositor protection scheme in South Africa, the inadequacy of the hitherto implicit guarantee system to protect depositors, and the poor record of the South African Reserve Bank in bank failure resolution, form the basis of the conclusion of the study, i.e., there is a case for the introduction of deposit insurance in South Africa. In order to assist South African policymakers in designing an effective deposit insurance scheme for the country, the thesis further provides a guide on how the most important design features of deposit insurance should be handled. This is in an attempt to ensure that the moral hazard problem inherent in deposit insurance is overcome.
- Full Text:
- Date Issued: 2004
- Authors: Ngaujake, Uahatjiri
- Date: 2004
- Subjects: Banks and banking -- South Africa , Bank deposits -- South Africa , Bank failures , Banks and banking -- State supervision , Deposit insurance , Consumer protection -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1025 , http://hdl.handle.net/10962/d1002760 , Banks and banking -- South Africa , Bank deposits -- South Africa , Bank failures , Banks and banking -- State supervision , Deposit insurance , Consumer protection -- South Africa
- Description: Banks play a pivotal role in economic growth and development of all countries and therefore the stability of the banking system is a vital goal of bank supervisors. Banks act as delegated monitors of depositors’ funds and this relationship, like all principal-agent relationships, presents agency problems. In the case of banks agency problems arise because depositors cannot accurately assess the financial health of banks due to the asymmetry of information existing between banks and depositors. Because banks possess private information on their borrowers, which depositors cannot access, it exposes depositors to risk of loss of deposits in cases of bank failures originating from nonrepayment of such loans. This asymmetry of information also exposes banks to runs by depositors and these runs can lead to bank failures with devastating effects for the financial system and the economy at large. It is for this reason that banks are regulated and supervised more than other institutions. Bank failures are a worldwide phenomenon and South Africa is no exception as evidenced by historical and recent bank failures in South Africa. This thesis investigates the desirability of introducing an explicit deposit insurance scheme in South Africa as a means of protecting small, unsophisticated depositors who are almost always the losers when banks fail, and promoting financial stability. The study finds that bank failures in South Africa are mainly attributable to mismanagement of banks, liquidity problems and fraud. Bank failures as a result of the aforementioned reasons have led to depositors losing their deposits in South Africa. The absence of a clearly defined depositor protection scheme in South Africa, the inadequacy of the hitherto implicit guarantee system to protect depositors, and the poor record of the South African Reserve Bank in bank failure resolution, form the basis of the conclusion of the study, i.e., there is a case for the introduction of deposit insurance in South Africa. In order to assist South African policymakers in designing an effective deposit insurance scheme for the country, the thesis further provides a guide on how the most important design features of deposit insurance should be handled. This is in an attempt to ensure that the moral hazard problem inherent in deposit insurance is overcome.
- Full Text:
- Date Issued: 2004
Psycho-medical expertise: the governmental interstice in the private/public, individual/society divide
- Authors: Macleod, Catriona I
- Date: 2004
- Language: English
- Type: Book chapter
- Identifier: vital:6297 , http://hdl.handle.net/10962/d1014782 , https://www.novapublishers.com/catalog/product_info.php?products_id=442
- Description: The continued dominance of the individual/society and private/public dualisms in psychological theory and practice has been bemoaned by critical psychologists. What we need to understand, however, is that these dualisms are essential to maintaining psycho-medical expertise in its present position of authority in the power/knowledge nexus of the human condition. Drawing on Derridean and Foucauldian theory, this chapter explicates how psychomedical expertise re-produces these dualisms while at the same time providing the interstice between the individual and the social, the private and the public required for governmental concerns to be installed in the everyday lives of people. The argument is illustrated by examples of expertise surrounding teenage pregnancy. Issues of governmental security translate into the incentive to manage risk at the individual level. For this to occur the individual needs to be rendered as an object of government. Psycho-medical experts achieve this by providing the language needed to describe her/him (in intricate detail), the grids of visibility to bring him/her into the plane of sight, and calibrations of normalisation. This object, finally, is converted into a subject of self-government who monitors and regulates him/herself and renders him/herself true to him/herself in confession to the expert. Psychomedical expertise is as much part of political power as are the formal bureaucratic instruments of government. However, this power is simultaneously masked and made possible by the individual/society and private/public divides. , Full text available on publisher site: https://www.novapublishers.com/catalog/product_info.php?products_id=442
- Full Text: false
- Date Issued: 2004
- Authors: Macleod, Catriona I
- Date: 2004
- Language: English
- Type: Book chapter
- Identifier: vital:6297 , http://hdl.handle.net/10962/d1014782 , https://www.novapublishers.com/catalog/product_info.php?products_id=442
- Description: The continued dominance of the individual/society and private/public dualisms in psychological theory and practice has been bemoaned by critical psychologists. What we need to understand, however, is that these dualisms are essential to maintaining psycho-medical expertise in its present position of authority in the power/knowledge nexus of the human condition. Drawing on Derridean and Foucauldian theory, this chapter explicates how psychomedical expertise re-produces these dualisms while at the same time providing the interstice between the individual and the social, the private and the public required for governmental concerns to be installed in the everyday lives of people. The argument is illustrated by examples of expertise surrounding teenage pregnancy. Issues of governmental security translate into the incentive to manage risk at the individual level. For this to occur the individual needs to be rendered as an object of government. Psycho-medical experts achieve this by providing the language needed to describe her/him (in intricate detail), the grids of visibility to bring him/her into the plane of sight, and calibrations of normalisation. This object, finally, is converted into a subject of self-government who monitors and regulates him/herself and renders him/herself true to him/herself in confession to the expert. Psychomedical expertise is as much part of political power as are the formal bureaucratic instruments of government. However, this power is simultaneously masked and made possible by the individual/society and private/public divides. , Full text available on publisher site: https://www.novapublishers.com/catalog/product_info.php?products_id=442
- Full Text: false
- Date Issued: 2004
Purification and characterisation of 20S proteasome from ostrich skeletal muscle and its role in meat tenderisation
- Authors: Thomas, Adele René
- Date: 2004
- Subjects: Proteolytic enzymes , Ostrich products industry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:11081 , http://hdl.handle.net/10948/320 , Proteolytic enzymes , Ostrich products industry
- Description: The proteasome is renowned for its high molecular weight, multisubunit and mulicatalytic nature. One of its many suggested roles is the degradation of myofibrillar proteins, and therefore it has been proposed to play a role in the meat tenderisation process. The aim of this study was therefore to isolate, purify and characterise the 20S proteasome from ostrich skeletal muscle, with a view to ultimately investigating its role in the tenderisation process of ostrich meat. The 20S proteasome was successfully isolated and purified from ostrich skeletal muscle using Toyopearl Super Q-650S, Sephacryl S-300, hydroxylapatite and Mono Q chromatographies. The intact molecule showed a molecular weight of 725 K and a pI of 6.67. The subunits showed a molecular weight range of 22.2-33.5 K and a pI range of 3-9. 2D-PAGE revealed at least 14 polypeptides. The amino acid composition of the intact enzyme and of each of the eight subunits separating on SDSPAGE, as well as the N-terminal sequences of five of the eight subunits, were determined. The trypsinlike (Tr-L), chymotrypsin-like (ChT-L), peptidylglutamyl peptide hydrolase (PGPH) and caseinolytic activities showed pH optima of 11, 9, 7-8 and 10.3, and temperature optima of 40, 60, 70 and 60oC, respectively. The pH stability range for all four activities was 5-12. The ChT-L and PGPH activities showed thermostabilities up to 60oC, whereas the Tr-L and caseinolytic activities were stable up to 40o C. The enzyme showed complex kinetics. It was inhibited by the peptide aldehyde Z-LLL-CHO and cysteine protease inhibitors. Cations had negligible effects on the enzyme, excepting for Ca2+ and Mg2+. Of the detergents tested, SDS had the most potent stimulatory effect, particularly on the PGPH and caseinolytic activities. The fatty acid studies showed that unsaturation enhanced the ChT-L and the caseinolytic activities, while it completely suppressed the Tr-L activity. Heating at 60oC for 1-2 min stimulated the caseinolytic and PGPH activities. The studies on the role of ostrich skeletal muscle 20S proteasome in ostrich meat tenderisation suggested a definite but minor role of this enzyme, based on the fact that it remained active throughout the 12 days of storage of ostrich M. iliofibularis meat at 4oC and that it participated in myofibril degradation of post-mortem muscle, but to a small degree. These results support the proposal that the proteasome comes into play after the calpains have initiated degradation. However, there was a lack of improvement in tenderness values and minimal myofibrillar degradation over the 12-day storage period of the ostrich M. iliofibularis meat, leading to the conclusion that the tenderisation of this meat was incomplete after 12 days.
- Full Text:
- Date Issued: 2004
- Authors: Thomas, Adele René
- Date: 2004
- Subjects: Proteolytic enzymes , Ostrich products industry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:11081 , http://hdl.handle.net/10948/320 , Proteolytic enzymes , Ostrich products industry
- Description: The proteasome is renowned for its high molecular weight, multisubunit and mulicatalytic nature. One of its many suggested roles is the degradation of myofibrillar proteins, and therefore it has been proposed to play a role in the meat tenderisation process. The aim of this study was therefore to isolate, purify and characterise the 20S proteasome from ostrich skeletal muscle, with a view to ultimately investigating its role in the tenderisation process of ostrich meat. The 20S proteasome was successfully isolated and purified from ostrich skeletal muscle using Toyopearl Super Q-650S, Sephacryl S-300, hydroxylapatite and Mono Q chromatographies. The intact molecule showed a molecular weight of 725 K and a pI of 6.67. The subunits showed a molecular weight range of 22.2-33.5 K and a pI range of 3-9. 2D-PAGE revealed at least 14 polypeptides. The amino acid composition of the intact enzyme and of each of the eight subunits separating on SDSPAGE, as well as the N-terminal sequences of five of the eight subunits, were determined. The trypsinlike (Tr-L), chymotrypsin-like (ChT-L), peptidylglutamyl peptide hydrolase (PGPH) and caseinolytic activities showed pH optima of 11, 9, 7-8 and 10.3, and temperature optima of 40, 60, 70 and 60oC, respectively. The pH stability range for all four activities was 5-12. The ChT-L and PGPH activities showed thermostabilities up to 60oC, whereas the Tr-L and caseinolytic activities were stable up to 40o C. The enzyme showed complex kinetics. It was inhibited by the peptide aldehyde Z-LLL-CHO and cysteine protease inhibitors. Cations had negligible effects on the enzyme, excepting for Ca2+ and Mg2+. Of the detergents tested, SDS had the most potent stimulatory effect, particularly on the PGPH and caseinolytic activities. The fatty acid studies showed that unsaturation enhanced the ChT-L and the caseinolytic activities, while it completely suppressed the Tr-L activity. Heating at 60oC for 1-2 min stimulated the caseinolytic and PGPH activities. The studies on the role of ostrich skeletal muscle 20S proteasome in ostrich meat tenderisation suggested a definite but minor role of this enzyme, based on the fact that it remained active throughout the 12 days of storage of ostrich M. iliofibularis meat at 4oC and that it participated in myofibril degradation of post-mortem muscle, but to a small degree. These results support the proposal that the proteasome comes into play after the calpains have initiated degradation. However, there was a lack of improvement in tenderness values and minimal myofibrillar degradation over the 12-day storage period of the ostrich M. iliofibularis meat, leading to the conclusion that the tenderisation of this meat was incomplete after 12 days.
- Full Text:
- Date Issued: 2004
Qongqothwane
- Nduna, S., Xakayi, S., Mgidi, A., Composer not specified, Dargie, Dave
- Authors: Nduna, S. , Xakayi, S. , Mgidi, A. , Composer not specified , Dargie, Dave
- Date: 2004
- Subjects: Folk music , Sacred music , Field recordings , Africa, Sub-Saharan , Africa South Africa Alice sa
- Language: IsiXhosa
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/343149 , vital:62974 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DDC344a-02
- Description: UFH music students accompanied by different types of marimba
- Full Text: false
- Date Issued: 2004
- Authors: Nduna, S. , Xakayi, S. , Mgidi, A. , Composer not specified , Dargie, Dave
- Date: 2004
- Subjects: Folk music , Sacred music , Field recordings , Africa, Sub-Saharan , Africa South Africa Alice sa
- Language: IsiXhosa
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/343149 , vital:62974 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DDC344a-02
- Description: UFH music students accompanied by different types of marimba
- Full Text: false
- Date Issued: 2004
Qongqothwane
- Nduna, S., Xakayi, S., Dubeni, N., Mgidi, A., Composer not specified, Dargie, Dave
- Authors: Nduna, S. , Xakayi, S. , Dubeni, N. , Mgidi, A. , Composer not specified , Dargie, Dave
- Date: 2004
- Subjects: Folk music , Sacred music , Field recordings , Africa, Sub-Saharan , Africa South Africa Alice sa
- Language: IsiXhosa
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/343154 , vital:62975 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DDC344a-03
- Description: UFH music students accompanied by different types of marimba
- Full Text: false
- Date Issued: 2004
- Authors: Nduna, S. , Xakayi, S. , Dubeni, N. , Mgidi, A. , Composer not specified , Dargie, Dave
- Date: 2004
- Subjects: Folk music , Sacred music , Field recordings , Africa, Sub-Saharan , Africa South Africa Alice sa
- Language: IsiXhosa
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/343154 , vital:62975 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DDC344a-03
- Description: UFH music students accompanied by different types of marimba
- Full Text: false
- Date Issued: 2004
Quantification of the photosynthetic performance of phosphorus-deficient Sorghum by means of chlorophyll-a fluorescence kinetics
- Ripley, Bradford S, Redfern, S P, Dames, Joanna F
- Authors: Ripley, Bradford S , Redfern, S P , Dames, Joanna F
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6456 , http://hdl.handle.net/10962/d1004464
- Description: Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 μmol mol^(–1)) or low (5 μmol mol^(–1)) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PI_ABS_); plants with increased PI_ABS_ manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.
- Full Text:
- Date Issued: 2004
- Authors: Ripley, Bradford S , Redfern, S P , Dames, Joanna F
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6456 , http://hdl.handle.net/10962/d1004464
- Description: Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 μmol mol^(–1)) or low (5 μmol mol^(–1)) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PI_ABS_); plants with increased PI_ABS_ manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.
- Full Text:
- Date Issued: 2004
Quantification of the photosynthetic performance of phosphorus-deficient Sorghum by means of chlorophyll-a fluorescence kinetics
- Ripley, Bradley S, Redfern, Sally P, Dames, Joanna F
- Authors: Ripley, Bradley S , Redfern, Sally P , Dames, Joanna F
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440444 , vital:73783 , https://hdl.handle.net/10520/EJC96177
- Description: Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 mmol mol-1) or low (5 mmol mol-1) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PIABS); plants with increased PIABS manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.
- Full Text:
- Date Issued: 2004
- Authors: Ripley, Bradley S , Redfern, Sally P , Dames, Joanna F
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440444 , vital:73783 , https://hdl.handle.net/10520/EJC96177
- Description: Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 mmol mol-1) or low (5 mmol mol-1) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PIABS); plants with increased PIABS manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.
- Full Text:
- Date Issued: 2004
Rare earth element geochemistry of the Insizwa lobe of the Mount Ayliff Complex, Eastern Cape, South Africa
- Authors: Marsh, Julian S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6736 , http://hdl.handle.net/10962/d1007548
- Description: New rare earth element (REE) data from all lithologies of the Insizwa lobe, Mount Ayliff Complex, are presented. On the basis of size and type of Eu anomaly, the geochemical subdivision of the complex as previously described is sustained and, additionally, the Top Gabbronorite of the Central Zone is shown to have formed from a magma that was compositionally distinct from other Central Zone magmas. The Basal Zone crystallized from magmas with large negative Eu anomalies probably acquired through crustal contamination. Previously recognized compositional heterogeneity in the contact rocks is also a feature of the REE. Overall, the Insizwa magmas had higher La/Sm ratios and, to a lesser extent, higher Gd/Yb ratios than Karoo basalts and appear to have no representatives in the basalt lava sequence of Lesotho.
- Full Text:
- Date Issued: 2004
- Authors: Marsh, Julian S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6736 , http://hdl.handle.net/10962/d1007548
- Description: New rare earth element (REE) data from all lithologies of the Insizwa lobe, Mount Ayliff Complex, are presented. On the basis of size and type of Eu anomaly, the geochemical subdivision of the complex as previously described is sustained and, additionally, the Top Gabbronorite of the Central Zone is shown to have formed from a magma that was compositionally distinct from other Central Zone magmas. The Basal Zone crystallized from magmas with large negative Eu anomalies probably acquired through crustal contamination. Previously recognized compositional heterogeneity in the contact rocks is also a feature of the REE. Overall, the Insizwa magmas had higher La/Sm ratios and, to a lesser extent, higher Gd/Yb ratios than Karoo basalts and appear to have no representatives in the basalt lava sequence of Lesotho.
- Full Text:
- Date Issued: 2004
Recent African derivation of Chrysomya putoria from C. chloropyga and mitochondrial DNA paraphyly of cytochrome oxidase subunit one in blowflies of forensic importance
- Wells, J D, Lunt, N, Villet, Martin H
- Authors: Wells, J D , Lunt, N , Villet, Martin H
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6888 , http://hdl.handle.net/10962/d1011648
- Description: Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.
- Full Text:
- Date Issued: 2004
- Authors: Wells, J D , Lunt, N , Villet, Martin H
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6888 , http://hdl.handle.net/10962/d1011648
- Description: Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.
- Full Text:
- Date Issued: 2004
Reduction in transport in wheat (Triticum aestivum) is caused by sustained phloem feeding by the Russian wheat aphid (Diuraphis noxia)
- Botha, Christiaan E J, Matsiliza, Babalwa
- Authors: Botha, Christiaan E J , Matsiliza, Babalwa
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6498 , http://hdl.handle.net/10962/d1004498
- Description: The Russian wheat aphid (Diuraphis noxia) feeds preferentially from the phloem of longitudinal veins of nonresistant wheat leaves. The xenobiotic, 5,6-CFDA was applied to exposed leaf blade mesophyll cells in control and aphid-infested plants. In control plants, the fluorophore moved approximately 5–6cm from the point of application of 5,6-CFDA within 3h of application. The fluorochrome was transported in the sieve tube companion cell complex, including those in the numerous interconnecting transverse veins. Leaf blades on which the Russian wheat aphid had been feeding demonstrated a marked decrease in 5,6-CF transport. Aphids feeding on the leaves formed local sinks and redirected the fluorophore (and presumably associated assimilate) to the aphids’ gut, with little longitudinal translocation of 5,6-CF below inserted stylets or aphid feeding areas. Aniline blue staining revealed massive deposits of wound and reaction callose caused by the aphids, with callose associated with the sieve plates, pore-plasmodesma between the companion cells and their associated sieve tubes, as well as with plasmodesmal aggregates in parenchymatous elements within the vascular bundles. Leaves that had been colonised by aphids but from which the aphids were removed, showed extensive wound callose deposits, which persisted for up to 48h after removal of aphid colonies, suggesting that the damage caused by aphid feeding is a long-term, non-transient event in non-resistant plants.
- Full Text:
- Date Issued: 2004
- Authors: Botha, Christiaan E J , Matsiliza, Babalwa
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6498 , http://hdl.handle.net/10962/d1004498
- Description: The Russian wheat aphid (Diuraphis noxia) feeds preferentially from the phloem of longitudinal veins of nonresistant wheat leaves. The xenobiotic, 5,6-CFDA was applied to exposed leaf blade mesophyll cells in control and aphid-infested plants. In control plants, the fluorophore moved approximately 5–6cm from the point of application of 5,6-CFDA within 3h of application. The fluorochrome was transported in the sieve tube companion cell complex, including those in the numerous interconnecting transverse veins. Leaf blades on which the Russian wheat aphid had been feeding demonstrated a marked decrease in 5,6-CF transport. Aphids feeding on the leaves formed local sinks and redirected the fluorophore (and presumably associated assimilate) to the aphids’ gut, with little longitudinal translocation of 5,6-CF below inserted stylets or aphid feeding areas. Aniline blue staining revealed massive deposits of wound and reaction callose caused by the aphids, with callose associated with the sieve plates, pore-plasmodesma between the companion cells and their associated sieve tubes, as well as with plasmodesmal aggregates in parenchymatous elements within the vascular bundles. Leaves that had been colonised by aphids but from which the aphids were removed, showed extensive wound callose deposits, which persisted for up to 48h after removal of aphid colonies, suggesting that the damage caused by aphid feeding is a long-term, non-transient event in non-resistant plants.
- Full Text:
- Date Issued: 2004
Religious nationalism and negotiation : Islamic identity and the resolution of the Israel/Palestine conflic
- Authors: De Villiers, Shirley
- Date: 2004
- Subjects: Arab-Israeli conflict Palestinian Arabs -- Civil rights -- Israel Nationalism -- Middle East Religion and politics -- Middle East Jewish-Arab relations Nationalism -- Religious aspects -- Islam -- History -- 20th century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2873 , http://hdl.handle.net/10962/d1007815
- Description: The use of violence in the Israel/Palestine conflict has been justified and legitimised by an appeal to religion. Militant Islamist organisations like Ramas have become central players in the Palestinian political landscape as a result of the popular support that they enjoy. This thesis aims to investigate the reasons for this support by analysing the Israel/Palestine conflict in terms of Ruman Needs Theory. According to this Theory, humans have essential needs that need to be fulfilled in order to ensure survival and development. Among these needs, the need for identity and recognition of identity is of vital importance. This thesis thus explores the concept of identity as a need, and investigates this need as it relates to inter-group conflict. In situating this theory in the Israel/Palestine conflict, the study exammes how organisations like Ramas have Islamised Palestinian national identity in order to garner political support. The central contention, then, is that the primary identity group of the Palestinian population is no longer nationalist, but Islamic/nationalist. In Islamising the conflict with Israel as well as Palestinian identity, Ramas has been able to justify its often indiscriminate use of violence by appealing to religion. The conflict is thus perceived to be one between two absolutes - that of Islam versus Judaism. In considering the conflict as one of identities struggling for survival in a climate of perceived threat, any attempt at resolution of the conflict needs to include a focus on needs-based issues. The problem-solving approach to negotiation allows for parties to consider issues of identity, recognition and security needs, and thus ensures that the root causes of conflicts are addressed, The contention is that this approach is vital to any conflict resolution strategy where identity needs are at stake, and it provides the grounding for the success of more traditional zero-sum bargaining methods. A recognition of Islamic identity in negotiation processes in Israel/Palestine may thus make for a more comprehensive conflict resolution strategy, and make the outcomes of negotiations more acceptable to the people of Palestine, thus undermining the acceptance of violence that exists at present.
- Full Text:
- Date Issued: 2004
- Authors: De Villiers, Shirley
- Date: 2004
- Subjects: Arab-Israeli conflict Palestinian Arabs -- Civil rights -- Israel Nationalism -- Middle East Religion and politics -- Middle East Jewish-Arab relations Nationalism -- Religious aspects -- Islam -- History -- 20th century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2873 , http://hdl.handle.net/10962/d1007815
- Description: The use of violence in the Israel/Palestine conflict has been justified and legitimised by an appeal to religion. Militant Islamist organisations like Ramas have become central players in the Palestinian political landscape as a result of the popular support that they enjoy. This thesis aims to investigate the reasons for this support by analysing the Israel/Palestine conflict in terms of Ruman Needs Theory. According to this Theory, humans have essential needs that need to be fulfilled in order to ensure survival and development. Among these needs, the need for identity and recognition of identity is of vital importance. This thesis thus explores the concept of identity as a need, and investigates this need as it relates to inter-group conflict. In situating this theory in the Israel/Palestine conflict, the study exammes how organisations like Ramas have Islamised Palestinian national identity in order to garner political support. The central contention, then, is that the primary identity group of the Palestinian population is no longer nationalist, but Islamic/nationalist. In Islamising the conflict with Israel as well as Palestinian identity, Ramas has been able to justify its often indiscriminate use of violence by appealing to religion. The conflict is thus perceived to be one between two absolutes - that of Islam versus Judaism. In considering the conflict as one of identities struggling for survival in a climate of perceived threat, any attempt at resolution of the conflict needs to include a focus on needs-based issues. The problem-solving approach to negotiation allows for parties to consider issues of identity, recognition and security needs, and thus ensures that the root causes of conflicts are addressed, The contention is that this approach is vital to any conflict resolution strategy where identity needs are at stake, and it provides the grounding for the success of more traditional zero-sum bargaining methods. A recognition of Islamic identity in negotiation processes in Israel/Palestine may thus make for a more comprehensive conflict resolution strategy, and make the outcomes of negotiations more acceptable to the people of Palestine, thus undermining the acceptance of violence that exists at present.
- Full Text:
- Date Issued: 2004
Replacing maize with barley in concetrates fed to jersey cows grazing on kikuyu/ryegrass pasture
- Authors: Lehmann, Maryna
- Date: 2004
- Subjects: Jersey cattle -- Feeding and feeds , Dairy cattle -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10732 , http://hdl.handle.net/10948/181 , Jersey cattle -- Feeding and feeds , Dairy cattle -- Feeding and feeds
- Description: The aim of the first study was to determine if barley could replace maize as an energy source in concentrates fed to dairy cows grazing on kikuyu/ryegrass pasture without affecting the milk production, milk composition, or cause metabolic disorders. Sixty Jersey cows, in early to mid lactation were randomly allocated to one of five treatments (n = 12) based on feeding concentrates with different ratios of maize to barley, ranging from 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Concentrates contained 12 MJ ME kg -1 and 130g CP kg-1 DM and cows were fed 3 kg (as-is) concentrate after each milking for a period of 42 days (14-day adaptation and 28-day measurement). Cows strip-grazed the irrigated kikuyu/ryegrass pastures (15.7 ± 1.8 percent DM; 20.2 ± 4.3 percent CP; 44.7 ± 3.5 percent NDF). Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein content. Body condition score and live weight were recorded at the start and end of the experimental period. Data of all the studies were subjected to a one-way ANOVA. Daily milk yield, FCM, MUN, milk fat yield, milk fat percent, protein yield, protein percent, live weight change, or body condition score change were not affected by treatment and values were 15.8 kg, 17.2 kg, 14.9 mg dl-1, 0.72 kg, 4.56 percent, 0.59 kg, 3.77 percent, 6.67 kg, and 0.15 BCS; 15.6 kg, 17.4 kg, 15.2 mg dl-1, 0.73 kg, 4.3 percent, 0.57 kg, 3.71 percent, 1.33 kg and 0.04 BCS; 17.2 kg, 17.9 kg, 15.2 mg dl-1, 0.74 kg, 4.36 percent, 0.63 kg, 3.71 percent, 0.33 kg and 0.08 BCS; 15.6 kg, 16.4 kg, 15.5 mg dl-1, 0.67 kg, 4.33 percent, 0.60 kg, 3.83 percent, -1.46 kg and 0.11 BCS; and 15.0 kg, 16.0 kg, 15.5 mg dl-1, 0.67 kg, 4.57 percent, 0.57 kg, 3.85 percent, 8.86 kg, and 0.05 BCS, respectively for the cows fed 100:0, 75:25, 50:50, 25:75 and 0:100 maize to barley ratio concentrate. According to these results, barley can replace maize without significantly affecting the milk production or milk composition. None of the cows presented any visible symptoms of acidosis. As it was clear from the results in the first study that maize could replace barley the aim of study 2A was therefore focused on determining the effect of feeding different levels of such a barley-based (2.4, 4.8 or 7.2 kg cow-1day-1) concentrate, on milk production, milk composition and live weight change of Jersey cows on kikuyu/ryegrass pasture (23.1 ± 2.95 percent DM, 11.1 ± 0.11 percent CP, 60.8 ± 0.58 percent NDF). Forty-five Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 15) involving different levels of concentrate (12 MJ ME and 130g CP kg-1 DM) feeding for a period of 42 days (14-day adaptation and 28-day measurement). Milk weights were also recorded daily, and milk samples collected weekly, and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. The results of this study indicated that increasing the concentrate level from 2.4 to 4.8 and 7.2kg cow-1day-1 did not increase the milk yield (14.0 kg, 15.2 kg, 14.4 kg; P = 0.19). The FCM production increased from 15.8 to 17.5kg (P = 0.04) as the concentrate level increased from 2.4 to 4.8kg cow-1day-1. Increasing the concentrate from 4.8 to 7.2kg cow-1day-1 did not result in a significant increase in FCM. The milk protein percent increased significantly from 3.4 - 3.6 percent when the concentrate feeding level was increased from 2.4 to 7.2kg cow-1day-1. The MUN levels were 17.09 mg dl-1, 16.03 5 mg dl-1, and 16.36 mg dl-1 for the 2.4, 4.8 and 7.2kg cow-1day-1 concentrate levels, respectively. This is well within the recommended MUN levels (12 – 18 mg dl-1) indicating that sufficient protein was fed to cows. Increasing the concentrate level from 4.8 to 7.2 kg cow-1day-1 did not increase production, probably due to a higher pasture substitution rate. Supplementing large quantities of rapidly fermentable grains, such as barley, can suppress rumen pH and may have a negative effect on the rate and extent of fibre digestion in the rumen. Therefore the aim of study 2B was not only to determine the effect of feeding different levels of a barley-based concentrate, on milk production, milk composition and live weight change, but was also to determine the effect of a low (4.8 kg cow-1day-1) versus a high (7.2 kg cow-1day-1) level of barley-based concentrate supplementation on ruminal DM and NDF degradability of Westerworld ryegrass sampled from the pastures that these cows were grazing on. Sixty Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 20) involving different levels of concentrate feeding. Concentrate (12 MJ ME, 130g CP kg-1 DM) was fed at 2.4, 4.8 or 7.2 kg cow-1day-1 for a period of 74 days (14-day adaptation and 60-day measurement). These cows stripgrazed irrigated kikuyu/ryegrass pastures (14.7 ± 4.37 percent DM, 25.1 ± 1.53 percent CP, and 44.4 ± 2.58 percent NDF) at a daily pasture allocation of 10 kg DM cow-1. Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. Twelve Jersey cows, fitted with ruminal cannulae, were randomly allocated to two of the three treatments in the production study and received either 2.4 or 7.2 kg cow-1 day-1, of the same barley-based concentrate, in a two-period crossover design. These cows strip-grazed the same irrigated kikuyu/ryegrass pastures as the sixty cows in the production study. Each period consisted of 21 days for adaptation and seven days for data collection. Rumen liquor samples were collected every 4 hours within a 24-hour cycle and repeated once. Rumen pH was measured immediately, recorded, and the supernatant fluid preserved and frozen, pending VFA analysis. The in situ nylon bag technique was used to determine DM and NDF degradation and dried samples of Westerworld ryegrass pasture were incubated for 0, 4, 8, 12, 20, 30, 48, 72 and 96 hours. The data were fitted in the non-linear model p = a + b (1-exp-ct) (Ørskov & McDonald, 1979). Daily milk production, fat corrected milk, milk fat yield and milk fat percent were not affected by treatment and values were 17.3 kg, 18.4 kg, 0.76 kg and 4.42 percent; 19.0 kg, 20.0 kg, 0.82 kg and 4.35 percent; and 18.1 kg, 19.1 kg, 0.79 kg and 4.37 percent for the 2.4, 4.8 and 7.2 kg cow-1 day-1 concentrate treatments, respectively. Milk protein percentage of cows on the 7.2 kg concentrate cow-1 day-1 was significantly higher than that of cows on 4.2 kg concentrate cow-1 day-1 feeding level. Live weight increased significantly as the level of concentrate feeding increased and values were 17.9 kg; and 28.9 kg on the 2.4 and 7.2kg concentrate treatment, respectively. There was a significant increase in the live weight of cows that were fed 7.2 kg cow-1 day-1 (as-is) in comparison to those cows that were fed 2.4 kg concentrate cow-1 day-1 (as-is). This may have resulted from more nutrients being partitioned to live weight gain rather than milk production. No further response in milk production was observed when concentrate daily feeding was increased from 4.8 to 7.2 kg cow-1 day-1. It is postulated that the higher concentrate allowance resulted in a higher substitution rate and lower DMI intake from pasture. 6 There was no significant decline in the rumen pH (6.2 ± 0.4 and 6.2 ± 0.5) when the concentrate level was increased from 2.4 to 7.2 kg cow-1 day-1 (as-is). The total VFA (118.1 ± 45.9 and 139.4 ± 45.6 mmol L-1) and isovalerate (0.009 ± 0.07 and 0.248 ± 0.52 mmol L-1) increased significantly when the concentrate was increased from 2.4 to 7.2 kg cow-1day-1. No other rumen parameters were affected by treatment. Ruminal DM and NDF degradability of the Kikuyu/ryegrass pature were not affected by the level of concentrate supplementation. An increase in the concentrate level from 2.4 to 7.2 kg cow-1day-1 did not reduce degradability of either DM (94.67 ± 5.97, 94.49 ± 5.09; P = 0.919) or NDF (92.15 ± 8.69, 94.4 ± 11.73; P = 0.451), respectively. Results of rumen parameters and PD values were within the range reported by Bargo et al., (2003), viz. pH 5.76 – 6.29, NH3-N concentration 8.7 – 32.2 mg dl-1, total VFA concentration 90.3 - 151.4 mmol L-1 and PD values 89.5 – 93.5 % reported by Bargo et al. (2003). According to these authors, there is no simple relationship between any amount of the concentrate supplemented, and the ruminal pH and concentrate feeding only affects the in situ ruminal digestion of pasture when it is fed, at quantities higher than 8 kg DM cow-1day-1 (Bargo et al., 2003).
- Full Text:
- Date Issued: 2004
- Authors: Lehmann, Maryna
- Date: 2004
- Subjects: Jersey cattle -- Feeding and feeds , Dairy cattle -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10732 , http://hdl.handle.net/10948/181 , Jersey cattle -- Feeding and feeds , Dairy cattle -- Feeding and feeds
- Description: The aim of the first study was to determine if barley could replace maize as an energy source in concentrates fed to dairy cows grazing on kikuyu/ryegrass pasture without affecting the milk production, milk composition, or cause metabolic disorders. Sixty Jersey cows, in early to mid lactation were randomly allocated to one of five treatments (n = 12) based on feeding concentrates with different ratios of maize to barley, ranging from 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Concentrates contained 12 MJ ME kg -1 and 130g CP kg-1 DM and cows were fed 3 kg (as-is) concentrate after each milking for a period of 42 days (14-day adaptation and 28-day measurement). Cows strip-grazed the irrigated kikuyu/ryegrass pastures (15.7 ± 1.8 percent DM; 20.2 ± 4.3 percent CP; 44.7 ± 3.5 percent NDF). Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein content. Body condition score and live weight were recorded at the start and end of the experimental period. Data of all the studies were subjected to a one-way ANOVA. Daily milk yield, FCM, MUN, milk fat yield, milk fat percent, protein yield, protein percent, live weight change, or body condition score change were not affected by treatment and values were 15.8 kg, 17.2 kg, 14.9 mg dl-1, 0.72 kg, 4.56 percent, 0.59 kg, 3.77 percent, 6.67 kg, and 0.15 BCS; 15.6 kg, 17.4 kg, 15.2 mg dl-1, 0.73 kg, 4.3 percent, 0.57 kg, 3.71 percent, 1.33 kg and 0.04 BCS; 17.2 kg, 17.9 kg, 15.2 mg dl-1, 0.74 kg, 4.36 percent, 0.63 kg, 3.71 percent, 0.33 kg and 0.08 BCS; 15.6 kg, 16.4 kg, 15.5 mg dl-1, 0.67 kg, 4.33 percent, 0.60 kg, 3.83 percent, -1.46 kg and 0.11 BCS; and 15.0 kg, 16.0 kg, 15.5 mg dl-1, 0.67 kg, 4.57 percent, 0.57 kg, 3.85 percent, 8.86 kg, and 0.05 BCS, respectively for the cows fed 100:0, 75:25, 50:50, 25:75 and 0:100 maize to barley ratio concentrate. According to these results, barley can replace maize without significantly affecting the milk production or milk composition. None of the cows presented any visible symptoms of acidosis. As it was clear from the results in the first study that maize could replace barley the aim of study 2A was therefore focused on determining the effect of feeding different levels of such a barley-based (2.4, 4.8 or 7.2 kg cow-1day-1) concentrate, on milk production, milk composition and live weight change of Jersey cows on kikuyu/ryegrass pasture (23.1 ± 2.95 percent DM, 11.1 ± 0.11 percent CP, 60.8 ± 0.58 percent NDF). Forty-five Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 15) involving different levels of concentrate (12 MJ ME and 130g CP kg-1 DM) feeding for a period of 42 days (14-day adaptation and 28-day measurement). Milk weights were also recorded daily, and milk samples collected weekly, and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. The results of this study indicated that increasing the concentrate level from 2.4 to 4.8 and 7.2kg cow-1day-1 did not increase the milk yield (14.0 kg, 15.2 kg, 14.4 kg; P = 0.19). The FCM production increased from 15.8 to 17.5kg (P = 0.04) as the concentrate level increased from 2.4 to 4.8kg cow-1day-1. Increasing the concentrate from 4.8 to 7.2kg cow-1day-1 did not result in a significant increase in FCM. The milk protein percent increased significantly from 3.4 - 3.6 percent when the concentrate feeding level was increased from 2.4 to 7.2kg cow-1day-1. The MUN levels were 17.09 mg dl-1, 16.03 5 mg dl-1, and 16.36 mg dl-1 for the 2.4, 4.8 and 7.2kg cow-1day-1 concentrate levels, respectively. This is well within the recommended MUN levels (12 – 18 mg dl-1) indicating that sufficient protein was fed to cows. Increasing the concentrate level from 4.8 to 7.2 kg cow-1day-1 did not increase production, probably due to a higher pasture substitution rate. Supplementing large quantities of rapidly fermentable grains, such as barley, can suppress rumen pH and may have a negative effect on the rate and extent of fibre digestion in the rumen. Therefore the aim of study 2B was not only to determine the effect of feeding different levels of a barley-based concentrate, on milk production, milk composition and live weight change, but was also to determine the effect of a low (4.8 kg cow-1day-1) versus a high (7.2 kg cow-1day-1) level of barley-based concentrate supplementation on ruminal DM and NDF degradability of Westerworld ryegrass sampled from the pastures that these cows were grazing on. Sixty Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 20) involving different levels of concentrate feeding. Concentrate (12 MJ ME, 130g CP kg-1 DM) was fed at 2.4, 4.8 or 7.2 kg cow-1day-1 for a period of 74 days (14-day adaptation and 60-day measurement). These cows stripgrazed irrigated kikuyu/ryegrass pastures (14.7 ± 4.37 percent DM, 25.1 ± 1.53 percent CP, and 44.4 ± 2.58 percent NDF) at a daily pasture allocation of 10 kg DM cow-1. Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. Twelve Jersey cows, fitted with ruminal cannulae, were randomly allocated to two of the three treatments in the production study and received either 2.4 or 7.2 kg cow-1 day-1, of the same barley-based concentrate, in a two-period crossover design. These cows strip-grazed the same irrigated kikuyu/ryegrass pastures as the sixty cows in the production study. Each period consisted of 21 days for adaptation and seven days for data collection. Rumen liquor samples were collected every 4 hours within a 24-hour cycle and repeated once. Rumen pH was measured immediately, recorded, and the supernatant fluid preserved and frozen, pending VFA analysis. The in situ nylon bag technique was used to determine DM and NDF degradation and dried samples of Westerworld ryegrass pasture were incubated for 0, 4, 8, 12, 20, 30, 48, 72 and 96 hours. The data were fitted in the non-linear model p = a + b (1-exp-ct) (Ørskov & McDonald, 1979). Daily milk production, fat corrected milk, milk fat yield and milk fat percent were not affected by treatment and values were 17.3 kg, 18.4 kg, 0.76 kg and 4.42 percent; 19.0 kg, 20.0 kg, 0.82 kg and 4.35 percent; and 18.1 kg, 19.1 kg, 0.79 kg and 4.37 percent for the 2.4, 4.8 and 7.2 kg cow-1 day-1 concentrate treatments, respectively. Milk protein percentage of cows on the 7.2 kg concentrate cow-1 day-1 was significantly higher than that of cows on 4.2 kg concentrate cow-1 day-1 feeding level. Live weight increased significantly as the level of concentrate feeding increased and values were 17.9 kg; and 28.9 kg on the 2.4 and 7.2kg concentrate treatment, respectively. There was a significant increase in the live weight of cows that were fed 7.2 kg cow-1 day-1 (as-is) in comparison to those cows that were fed 2.4 kg concentrate cow-1 day-1 (as-is). This may have resulted from more nutrients being partitioned to live weight gain rather than milk production. No further response in milk production was observed when concentrate daily feeding was increased from 4.8 to 7.2 kg cow-1 day-1. It is postulated that the higher concentrate allowance resulted in a higher substitution rate and lower DMI intake from pasture. 6 There was no significant decline in the rumen pH (6.2 ± 0.4 and 6.2 ± 0.5) when the concentrate level was increased from 2.4 to 7.2 kg cow-1 day-1 (as-is). The total VFA (118.1 ± 45.9 and 139.4 ± 45.6 mmol L-1) and isovalerate (0.009 ± 0.07 and 0.248 ± 0.52 mmol L-1) increased significantly when the concentrate was increased from 2.4 to 7.2 kg cow-1day-1. No other rumen parameters were affected by treatment. Ruminal DM and NDF degradability of the Kikuyu/ryegrass pature were not affected by the level of concentrate supplementation. An increase in the concentrate level from 2.4 to 7.2 kg cow-1day-1 did not reduce degradability of either DM (94.67 ± 5.97, 94.49 ± 5.09; P = 0.919) or NDF (92.15 ± 8.69, 94.4 ± 11.73; P = 0.451), respectively. Results of rumen parameters and PD values were within the range reported by Bargo et al., (2003), viz. pH 5.76 – 6.29, NH3-N concentration 8.7 – 32.2 mg dl-1, total VFA concentration 90.3 - 151.4 mmol L-1 and PD values 89.5 – 93.5 % reported by Bargo et al. (2003). According to these authors, there is no simple relationship between any amount of the concentrate supplemented, and the ruminal pH and concentrate feeding only affects the in situ ruminal digestion of pasture when it is fed, at quantities higher than 8 kg DM cow-1day-1 (Bargo et al., 2003).
- Full Text:
- Date Issued: 2004