The effect of plant-derived dietary protein sources on cultured abalone Haliotis midae (L. 1758) digestive physiology
- Authors: Wright, Jason Geoffrey
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa , Haliotis midae -- Nutrition -- South Africa , Haliotis midae -- Physiology -- South Africa , Haliotis midae -- South Africa -- Growth , Haliotis midae -- Digestive organs , Abalone culture -- South Africa , Plant proteins as feed
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176803 , vital:42760
- Description: The growth and feed conversion ratio of farmed abalone Haliotis midae (L. 1758) fed a formulated diet varies in feeds with different protein sources. To better understand this, the effect that various combinations of dietary soybean meal (SBM), sunflower meal (SFM) and fishmeal (FM) had on the digestive efficiency of farmed H. midae when included in a formulated feed, were assessed. The aim of this study was to investigate the effect that plant-based proteins had on abalone digestion and gut-bacterial profile of cultured adult abalone when combined with fishmeal. This was done by analysing the chymotrypsin (protease) and cellulase (carbohydrase) digestive enzyme activities from whole-gut sections of farmed abalone that were fed one of four diets for 12 months: FM-only, SBM-only, fishmeal and soybean meal (FM-SBM), and fishmeal and sunflower meal (FM-SFM). There were significant interactions between the diets, sampling date, and sex of the abalone, which had an influence on the cellulase activities in the digestive tracts of the animals. Those fed the SBM diet had the highest cellulase activity by the end of the sampling period (ANOVA; df = 9; F = 2.9; P = 0.005). The significant interactions between diet and sampling date influenced the chymotrypsin activities of abalone. Animals fed the FM diet had the highest activity of chymotrypsin for most of the sampling period (ANOVA; df = 9; F = 2.5; P = 0.01). Therefore, diet did have an impact on the cellulase and chymotrypsin activities of abalone fed either combination diets (FM-SBM; FM-SFM) or single protein diets (FM; SBM). The presence of plant material such as cellulose fibres in the diets containing plant proteins may have influenced the cellulase activity levels of each treatment as it would have stimulated endogenous and exogenous cellulase production. However, treatments with the highest crude fibre content, SBM and FM-SFM, resulted in differing activities. The activity levels of chymotrypsin may have been impacted by the protein type, presence of protein inhibitors and temporal changes in utilisation. Abalone fed the FM diet exhibited the highest chymotrypsin activities on sampling day 182, which was in summer. Animals fed the treatment diets containing fishmeal also developed their reproductive tissues, and may explain the low chymotrypsin activities in abalone fed SBM-only. Additionally, the presence of allergenic compounds would have influenced enzyme activity, as they would have negatively affected the nutrient utilisation and absorptive capacity. Fluctuations in water temperature may have had an effect on enzyme activity, as activities were highest during summer, when seawater temperatures are most variable. A change to lowered water temperatures are known to trigger the growth of digestive epithelial tissue in abalone to allow for increased enzyme secretions and nutrient absorption (Schaeffer et al. 2013). The effect that plant protein inclusion in abalone diets had on the gut-microbiota was revealed by analysing the differences in gut-bacterial community profiles, through the use of metagenomic sequencing. The relative abundance of the phylum Verrucomicrobia, class Verrcomicrobiae and the genus Rubritalea were highest in the SBM diet. These bacterial groups were also influenced by the plant material from soybean meal, as hydrolysed cellulose is broken down by cellulases, and allowed for the proliferation of Rubritalea bacteria due to them using cellobiose as an energy source. The presence of Bacteroidetes was due to the phyla having bacterial species that can breakdown proteins and species that can break down carbohydrates. The animal protein present in the composition of the FM diet had a positive influence on proteolytic Bacteroidetes growth. The high levels of cellulose from the plant fibres in the soybean meal-only diet (SBM) promoted growth of saccharolytic Bacteroidetes. Tenericutes bacteria’s prominence was due to the higher plant fibres from the soybean meal as some Mycoplasma are known to degrade polysaccharides. Therefore, exposure to formulated feeds with high levels of these plant materials would allow for high proliferation. The thesis established that plant-derived dietary proteins in formulated feeds result in an effect on digestive enzyme activity and a difference in the community structure of gut bacteria in H. midae abalone. The results from the current research highlight the importance of studying abalone gut physiology when investigating the impacts of formulated feed composition, and can be used as an additional factor when determining the efficacy of a dietary component. Further research on the gut-bacterial groups and different digestive enzymes of H. midae abalone is encouraged, in order to create a holistic view on their response to dietary plant proteins inclusion in formulated feeds, thus reducing the need for fishmeal protein. , Thesis (MSc)-- Rhodes University, Faculty of Science, Department of Ichthyology and Fisheries Science, 2021
- Full Text:
- Authors: Wright, Jason Geoffrey
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa , Haliotis midae -- Nutrition -- South Africa , Haliotis midae -- Physiology -- South Africa , Haliotis midae -- South Africa -- Growth , Haliotis midae -- Digestive organs , Abalone culture -- South Africa , Plant proteins as feed
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176803 , vital:42760
- Description: The growth and feed conversion ratio of farmed abalone Haliotis midae (L. 1758) fed a formulated diet varies in feeds with different protein sources. To better understand this, the effect that various combinations of dietary soybean meal (SBM), sunflower meal (SFM) and fishmeal (FM) had on the digestive efficiency of farmed H. midae when included in a formulated feed, were assessed. The aim of this study was to investigate the effect that plant-based proteins had on abalone digestion and gut-bacterial profile of cultured adult abalone when combined with fishmeal. This was done by analysing the chymotrypsin (protease) and cellulase (carbohydrase) digestive enzyme activities from whole-gut sections of farmed abalone that were fed one of four diets for 12 months: FM-only, SBM-only, fishmeal and soybean meal (FM-SBM), and fishmeal and sunflower meal (FM-SFM). There were significant interactions between the diets, sampling date, and sex of the abalone, which had an influence on the cellulase activities in the digestive tracts of the animals. Those fed the SBM diet had the highest cellulase activity by the end of the sampling period (ANOVA; df = 9; F = 2.9; P = 0.005). The significant interactions between diet and sampling date influenced the chymotrypsin activities of abalone. Animals fed the FM diet had the highest activity of chymotrypsin for most of the sampling period (ANOVA; df = 9; F = 2.5; P = 0.01). Therefore, diet did have an impact on the cellulase and chymotrypsin activities of abalone fed either combination diets (FM-SBM; FM-SFM) or single protein diets (FM; SBM). The presence of plant material such as cellulose fibres in the diets containing plant proteins may have influenced the cellulase activity levels of each treatment as it would have stimulated endogenous and exogenous cellulase production. However, treatments with the highest crude fibre content, SBM and FM-SFM, resulted in differing activities. The activity levels of chymotrypsin may have been impacted by the protein type, presence of protein inhibitors and temporal changes in utilisation. Abalone fed the FM diet exhibited the highest chymotrypsin activities on sampling day 182, which was in summer. Animals fed the treatment diets containing fishmeal also developed their reproductive tissues, and may explain the low chymotrypsin activities in abalone fed SBM-only. Additionally, the presence of allergenic compounds would have influenced enzyme activity, as they would have negatively affected the nutrient utilisation and absorptive capacity. Fluctuations in water temperature may have had an effect on enzyme activity, as activities were highest during summer, when seawater temperatures are most variable. A change to lowered water temperatures are known to trigger the growth of digestive epithelial tissue in abalone to allow for increased enzyme secretions and nutrient absorption (Schaeffer et al. 2013). The effect that plant protein inclusion in abalone diets had on the gut-microbiota was revealed by analysing the differences in gut-bacterial community profiles, through the use of metagenomic sequencing. The relative abundance of the phylum Verrucomicrobia, class Verrcomicrobiae and the genus Rubritalea were highest in the SBM diet. These bacterial groups were also influenced by the plant material from soybean meal, as hydrolysed cellulose is broken down by cellulases, and allowed for the proliferation of Rubritalea bacteria due to them using cellobiose as an energy source. The presence of Bacteroidetes was due to the phyla having bacterial species that can breakdown proteins and species that can break down carbohydrates. The animal protein present in the composition of the FM diet had a positive influence on proteolytic Bacteroidetes growth. The high levels of cellulose from the plant fibres in the soybean meal-only diet (SBM) promoted growth of saccharolytic Bacteroidetes. Tenericutes bacteria’s prominence was due to the higher plant fibres from the soybean meal as some Mycoplasma are known to degrade polysaccharides. Therefore, exposure to formulated feeds with high levels of these plant materials would allow for high proliferation. The thesis established that plant-derived dietary proteins in formulated feeds result in an effect on digestive enzyme activity and a difference in the community structure of gut bacteria in H. midae abalone. The results from the current research highlight the importance of studying abalone gut physiology when investigating the impacts of formulated feed composition, and can be used as an additional factor when determining the efficacy of a dietary component. Further research on the gut-bacterial groups and different digestive enzymes of H. midae abalone is encouraged, in order to create a holistic view on their response to dietary plant proteins inclusion in formulated feeds, thus reducing the need for fishmeal protein. , Thesis (MSc)-- Rhodes University, Faculty of Science, Department of Ichthyology and Fisheries Science, 2021
- Full Text:
The effect of sectoral foreign direct investment on sectoral growth and sectoral employment in South Africa
- Authors: Paul, Bernice Nicole
- Date: 2021-04
- Subjects: Investments, Foreign -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Economic policy , Gross domestic product -- South Africa , UNCTAD-ICTSD Project on IPRs and Sustainable Development , Unemployment -- South Africa
- Language: English
- Type: thesis , text , Master , MCom
- Identifier: http://hdl.handle.net/10962/177964 , vital:42894
- Description: Over several decades past, developing countries have received increased amounts of Foreign Direct Investment (FDI). This form of investment has been welcomed because of the perceived benefits attached to it. FDI is seen as an important driver of economic development for many nations. For South Africa specifically, GDP growth rates have remained less than required, unemployment rates have reached staggering levels, poverty and inequality levels are increasing and the list goes on. Considering the perceived benefits of FDI, one may argue that FDI can play a crucial role in reducing the mentioned challenges facing the nation, however, only if directed to initiatives contributing to growth and employment. The 2015 Investment Policy Framework for Sustainable Development includes an action menu promoting investment in sectors relating to the achievement of the Sustainable Development Goals (SDGs). Therefore, this study is aimed at investigating the relationship between sector FDI and sector growth in addition to investigating the effect of sector FDI on sector employment over the period 2000Q1 to 2016Q4 for six of South Africa’s economic sectors. The reason for such a study is based on the premise that developing nations such as South Africa lack sound trade and industrial policies favorable to foreign investors. This then leads to the nation failing to attract higher volumes of FDI which could be used to address structural challenges facing the country. It is therefore important to identify sectors in which FDI has resulted in growth and employment so that when policies are considered, the right FDI is targeted. A comprehensive review of existing theoretical and empirical literature showed that FDI does result in economic growth for developed and developing countries, although FDI crowds out domestic investment in the short run. Literature on the effect of FDI on employment showed diverse effects. Some studies found FDI to increase employment overall, other studies found FDI to increase employment only during periods of restructuring and some studies found FDI to result in job losses. For South African sectors, the present study finds that the financial services sector receives the highest volume of South African FDI, followed by the mining and quarrying sector and the manufacturing, however, FDI in all six sectors under study is associated with increased growth and employment. This finding suggests that the financial services sector has received increased volumes of FDI as a result of financialization of the South African economy. It is this increased FDI in the financial services sector that is directed to income redistribution from the real sector to the finance sector. This study employed econometric techniques and methods of analysis to investigate the relationship between sector FDI and sector growth, and the effect of sector FDI on sector employment. Panel cointegration tests were conducted for all six sectors included in the study to establish if long run equilibrium relationships exist among integrated variables. The Johansen-Fisher panel cointegration test revealed that there is evidence of cointegration in four of the six sectors. Since cointegration was established, the study proceeded to perform the Dumitrescu-Hurlin panel causality analysis and estimate a Panel Vector Error Correction Model (VECM). Results from the causality analysis found a unidirectional causality relationship between FDI and GDP growth, while the panel VECM found FDI to have a significant effect on growth in all sectors. The Seemingly Unrelated Regression (SUR) model employed to investigate the effect of FDI on employment found FDI to have an insignificant effect on employment in all sectors included, although the signs of the coefficients suggest that FDI is associated with increased employment and rising wages is associated with increased productivity growth. Since this study finds that FDI is associated with increased GDP growth in all six sectors under study, policy makers should devise strategies to attract FDI in sectors such as the transportation, storage and communication sector and the electricity, gas and water sector as FDI in these sectors are associated with increased growth however, they receive very low levels of FDI. There are a number of reasons for this, therefore, government institutions and policy makers should investigate the reasons for these low levels of FDI inflows into these sectors so that they can devise further strategies to address these reasons and perhaps attract higher levels of FDI into these sectors. Spillover benefits play a major role in host nations participating in FDI therefore, prior to entering into bilateral treaty agreements, policy makers should ensure that foreign investors are compelled to create jobs, offer training and qualifications etc. through their investments so that some of the SDGs can be achieved. Additionally, this study finds a positive, statistically insignificant relationship between FDI and employment. FDI may not have a significant relationship on employment due to jobless growth and capital-intensive growth rather than labor-intensive growth. Such a situation calls for government intervention. Skills shortage is a rising problem in South Africa; therefore, investors choose to employ advanced technologies rather than people. Under such circumstances, governments are encouraged to invest resources into skills development so that human capital are not completely replaced by technology. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Authors: Paul, Bernice Nicole
- Date: 2021-04
- Subjects: Investments, Foreign -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Economic policy , Gross domestic product -- South Africa , UNCTAD-ICTSD Project on IPRs and Sustainable Development , Unemployment -- South Africa
- Language: English
- Type: thesis , text , Master , MCom
- Identifier: http://hdl.handle.net/10962/177964 , vital:42894
- Description: Over several decades past, developing countries have received increased amounts of Foreign Direct Investment (FDI). This form of investment has been welcomed because of the perceived benefits attached to it. FDI is seen as an important driver of economic development for many nations. For South Africa specifically, GDP growth rates have remained less than required, unemployment rates have reached staggering levels, poverty and inequality levels are increasing and the list goes on. Considering the perceived benefits of FDI, one may argue that FDI can play a crucial role in reducing the mentioned challenges facing the nation, however, only if directed to initiatives contributing to growth and employment. The 2015 Investment Policy Framework for Sustainable Development includes an action menu promoting investment in sectors relating to the achievement of the Sustainable Development Goals (SDGs). Therefore, this study is aimed at investigating the relationship between sector FDI and sector growth in addition to investigating the effect of sector FDI on sector employment over the period 2000Q1 to 2016Q4 for six of South Africa’s economic sectors. The reason for such a study is based on the premise that developing nations such as South Africa lack sound trade and industrial policies favorable to foreign investors. This then leads to the nation failing to attract higher volumes of FDI which could be used to address structural challenges facing the country. It is therefore important to identify sectors in which FDI has resulted in growth and employment so that when policies are considered, the right FDI is targeted. A comprehensive review of existing theoretical and empirical literature showed that FDI does result in economic growth for developed and developing countries, although FDI crowds out domestic investment in the short run. Literature on the effect of FDI on employment showed diverse effects. Some studies found FDI to increase employment overall, other studies found FDI to increase employment only during periods of restructuring and some studies found FDI to result in job losses. For South African sectors, the present study finds that the financial services sector receives the highest volume of South African FDI, followed by the mining and quarrying sector and the manufacturing, however, FDI in all six sectors under study is associated with increased growth and employment. This finding suggests that the financial services sector has received increased volumes of FDI as a result of financialization of the South African economy. It is this increased FDI in the financial services sector that is directed to income redistribution from the real sector to the finance sector. This study employed econometric techniques and methods of analysis to investigate the relationship between sector FDI and sector growth, and the effect of sector FDI on sector employment. Panel cointegration tests were conducted for all six sectors included in the study to establish if long run equilibrium relationships exist among integrated variables. The Johansen-Fisher panel cointegration test revealed that there is evidence of cointegration in four of the six sectors. Since cointegration was established, the study proceeded to perform the Dumitrescu-Hurlin panel causality analysis and estimate a Panel Vector Error Correction Model (VECM). Results from the causality analysis found a unidirectional causality relationship between FDI and GDP growth, while the panel VECM found FDI to have a significant effect on growth in all sectors. The Seemingly Unrelated Regression (SUR) model employed to investigate the effect of FDI on employment found FDI to have an insignificant effect on employment in all sectors included, although the signs of the coefficients suggest that FDI is associated with increased employment and rising wages is associated with increased productivity growth. Since this study finds that FDI is associated with increased GDP growth in all six sectors under study, policy makers should devise strategies to attract FDI in sectors such as the transportation, storage and communication sector and the electricity, gas and water sector as FDI in these sectors are associated with increased growth however, they receive very low levels of FDI. There are a number of reasons for this, therefore, government institutions and policy makers should investigate the reasons for these low levels of FDI inflows into these sectors so that they can devise further strategies to address these reasons and perhaps attract higher levels of FDI into these sectors. Spillover benefits play a major role in host nations participating in FDI therefore, prior to entering into bilateral treaty agreements, policy makers should ensure that foreign investors are compelled to create jobs, offer training and qualifications etc. through their investments so that some of the SDGs can be achieved. Additionally, this study finds a positive, statistically insignificant relationship between FDI and employment. FDI may not have a significant relationship on employment due to jobless growth and capital-intensive growth rather than labor-intensive growth. Such a situation calls for government intervention. Skills shortage is a rising problem in South Africa; therefore, investors choose to employ advanced technologies rather than people. Under such circumstances, governments are encouraged to invest resources into skills development so that human capital are not completely replaced by technology. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
The reproductive performance, demography and spatial ecology of an extralimital white rhinoceros population
- Authors: Truter, Anja
- Date: 2021-04
- Subjects: White rhinoceros -- South Africa -- Eastern Cape , White rhinoceros -- Effect of poaching on -- South Africa -- Eastern Cape , White rhinoceros -- South Africa -- Eastern Cape -- Reproduction , White rhinoceros -- Dispersal -- South Africa -- Eastern Cape , White rhinoceros -- Food -- South Africa -- Eastern Cape , White rhinoceros -- Behavior -- South Africa -- Eastern Cape , Spatial ecology -- South Africa -- Eastern Cape , Animal populations -- South Africa -- Eastern Cape , Endangered species -- South Africa -- Eastern Cape , Spatial behavior in animals -- South Africa -- Eastern Cape , Shamwari Game Reserve (South Africa)
- Language: English
- Type: thesis , text , Master , MSc
- Identifier: http://hdl.handle.net/10962/177975 , vital:42895
- Description: The white rhinoceros (Ceratotherium simum) (hereafter rhino) is under threat of becoming extinct due to continued poaching for its horns. In South Africa and elsewhere in Africa private landowners have, over the last few decades, contributed to the conservation of various species, including rhinos, even in areas where they have not occurred historically (i.e., where they are extralimital). Unfortunately, very few studies have investigated the conservation contribution of extralimital white rhinos on private reserves to the overall meta-population and/or their reproductive performance. The first aim of my study was therefore to determine whether or not the white rhinos introduced to a private game reserve in the Eastern Cape Province in 1992 have been successful from a reproductive perspective. I calculated inter-calving intervals, age at first calving, conception period, sex ratio, fecundity and fertility rates for white rhinos over this 28-year period. The average annual population growth rate for the rhinos was 10%, which is higher than the recommended 5% by the Rhino Management Group. Trends in density-dependent parameters such as age at first calving and inter-calving intervals also indicated that my study population is still well below carrying capacity for white rhinos and is contributing positively to white rhino conservation in South Africa. The second aim of my study was to investigate home range size and vegetation preferences of white rhinos. Home ranges were mostly larger for all age groups compared to rhinos in their native range. Previously cultivated lands (dominated by several grass species) were preferred by all rhino age groups. The rehabilitation of these previous agricultural-based pastures has likely contributed to the successful introduction of the white rhino as an extralimital megaherbivore in the Eastern Cape. I conclude that although extralimital white rhino populations in the Eastern Cape can be successful from a reproductive perspective, their potential impact on the indigenous biodiversity of the region should be a key future research priority. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Authors: Truter, Anja
- Date: 2021-04
- Subjects: White rhinoceros -- South Africa -- Eastern Cape , White rhinoceros -- Effect of poaching on -- South Africa -- Eastern Cape , White rhinoceros -- South Africa -- Eastern Cape -- Reproduction , White rhinoceros -- Dispersal -- South Africa -- Eastern Cape , White rhinoceros -- Food -- South Africa -- Eastern Cape , White rhinoceros -- Behavior -- South Africa -- Eastern Cape , Spatial ecology -- South Africa -- Eastern Cape , Animal populations -- South Africa -- Eastern Cape , Endangered species -- South Africa -- Eastern Cape , Spatial behavior in animals -- South Africa -- Eastern Cape , Shamwari Game Reserve (South Africa)
- Language: English
- Type: thesis , text , Master , MSc
- Identifier: http://hdl.handle.net/10962/177975 , vital:42895
- Description: The white rhinoceros (Ceratotherium simum) (hereafter rhino) is under threat of becoming extinct due to continued poaching for its horns. In South Africa and elsewhere in Africa private landowners have, over the last few decades, contributed to the conservation of various species, including rhinos, even in areas where they have not occurred historically (i.e., where they are extralimital). Unfortunately, very few studies have investigated the conservation contribution of extralimital white rhinos on private reserves to the overall meta-population and/or their reproductive performance. The first aim of my study was therefore to determine whether or not the white rhinos introduced to a private game reserve in the Eastern Cape Province in 1992 have been successful from a reproductive perspective. I calculated inter-calving intervals, age at first calving, conception period, sex ratio, fecundity and fertility rates for white rhinos over this 28-year period. The average annual population growth rate for the rhinos was 10%, which is higher than the recommended 5% by the Rhino Management Group. Trends in density-dependent parameters such as age at first calving and inter-calving intervals also indicated that my study population is still well below carrying capacity for white rhinos and is contributing positively to white rhino conservation in South Africa. The second aim of my study was to investigate home range size and vegetation preferences of white rhinos. Home ranges were mostly larger for all age groups compared to rhinos in their native range. Previously cultivated lands (dominated by several grass species) were preferred by all rhino age groups. The rehabilitation of these previous agricultural-based pastures has likely contributed to the successful introduction of the white rhino as an extralimital megaherbivore in the Eastern Cape. I conclude that although extralimital white rhino populations in the Eastern Cape can be successful from a reproductive perspective, their potential impact on the indigenous biodiversity of the region should be a key future research priority. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
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