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:
Effect of diet and sex-sorting on growth and gonad development in farmed South African abalone, Haliotis midae
- Authors: Ayres, Devin William Philip
- Date: 2014
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5357 , http://hdl.handle.net/10962/d1010856 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Description: Abalone, Haliotis midae, farmers in South Africa that feed formulated diets reported a periodic drop in abalone growth during periods of increased gonad development. A large drop in abalone biomass was noticed after presumed spawning events. This study was aimed to determine the effect of diet and sex-sorting on gonad development in abalone. Experiments were conducted on a commercial abalone farm from July 2012 to the end of June 2013. Isonitrogenous and isoenergetic diets were formulated with two protein sources. A fishmeal and soybean meal (S-diet) diet and a fishmeal only (F-diet) diet were fed to abalone (50 - 70 g abalone⁻¹) over 12 months. Weight and length gain, gonad bulk index (GBI), visceral index (%) and meat mass index (%) were determined monthly and seasonally. A histological study on the female gonads was conducted. This study also included an experiment to test the effect of sex-sorting (70 - 80 g abalone⁻¹) on growth and body composition with treatments including males (M), females (F) and equal numbers of males and females (MF). Weight gain and length gain were faster in S-diet-fed abalone (RM-ANOVA, F ₍₁, ₁₆₎ = 7.77, p = 0.01; F ₍₁, ₆₉₎ = 49.9, p < 0.001, respectively). Gonad development was significantly affected by the inclusion of soybean meal with S-diet-fed abalone showing higher GBI-values than F-diet-fed abalone (RM-ANOVA, F ₍₁, ₃₃)= 16.22, p = 0.0003). Male abalone had higher GBI-values than females (RM-ANOVA, F ₍₁, ₃₃₎ = 39.87, p < 0.0001). There was no significant difference in average feed conversion ratio (FCR) between diets over time (RM-ANOVA, F ₍₁, ₂₁₎ = 0.008, p = 0.97). However, average FCR-values were significantly highest between November 2012 and March 2013, the presumed spawning season. The visceral mass (gut and gonad) as a proportion of whole mass (visceral index, %) was significantly higher in abalone fed the S-diet (RM-ANOVA; F ₍₁, ₆₉₎ = 68.06, p < 0.0001). There was no difference in meat mass index (%) between diets for both male and female abalone (RM-ANOVA; F ₍₇, ₂₄₈₎ = 0.80, p = 0.60; F ₍₇, ₂₄₁₎ = 1.7, p = 0.11,respectively). Meat mass index significantly decreased from September 2012 to February 2013 coinciding with the period of high GBI-values. The distribution of oocyte maturity stages differed between diets. The majority of oocytes within S-diet-fed abalone were fully mature stage 8 oocytes compared to a majority of stage 7 oocytes in F-diet-fed abalone. Histology corroborated peaks in GBI-values for abalone fed both diets. There was no significant difference in growth, GBI, visceral index (%) and meat mass index (%) between abalone sorted into monosex and mixed-sex populations. Thus, the presence of the opposite sex did not have an effect on growth and gonad mass in H. midae. The phytoestrogens daidzin, glycitin, genistin, daidzein, glycitein and genistein were present in soybean meal and only traceable amounts were found in the F-diet. This study provided evidence that soybean meal present in formulated feed affected growth and gonad development in H.midae. The difference in the distribution of the maturity stages of oocytes was affected by diet. Sex-sorting abalone into monosex and mixed-sex populations had no influence on weight and length gain and gonad development.
- Full Text:
- Authors: Ayres, Devin William Philip
- Date: 2014
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5357 , http://hdl.handle.net/10962/d1010856 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Description: Abalone, Haliotis midae, farmers in South Africa that feed formulated diets reported a periodic drop in abalone growth during periods of increased gonad development. A large drop in abalone biomass was noticed after presumed spawning events. This study was aimed to determine the effect of diet and sex-sorting on gonad development in abalone. Experiments were conducted on a commercial abalone farm from July 2012 to the end of June 2013. Isonitrogenous and isoenergetic diets were formulated with two protein sources. A fishmeal and soybean meal (S-diet) diet and a fishmeal only (F-diet) diet were fed to abalone (50 - 70 g abalone⁻¹) over 12 months. Weight and length gain, gonad bulk index (GBI), visceral index (%) and meat mass index (%) were determined monthly and seasonally. A histological study on the female gonads was conducted. This study also included an experiment to test the effect of sex-sorting (70 - 80 g abalone⁻¹) on growth and body composition with treatments including males (M), females (F) and equal numbers of males and females (MF). Weight gain and length gain were faster in S-diet-fed abalone (RM-ANOVA, F ₍₁, ₁₆₎ = 7.77, p = 0.01; F ₍₁, ₆₉₎ = 49.9, p < 0.001, respectively). Gonad development was significantly affected by the inclusion of soybean meal with S-diet-fed abalone showing higher GBI-values than F-diet-fed abalone (RM-ANOVA, F ₍₁, ₃₃)= 16.22, p = 0.0003). Male abalone had higher GBI-values than females (RM-ANOVA, F ₍₁, ₃₃₎ = 39.87, p < 0.0001). There was no significant difference in average feed conversion ratio (FCR) between diets over time (RM-ANOVA, F ₍₁, ₂₁₎ = 0.008, p = 0.97). However, average FCR-values were significantly highest between November 2012 and March 2013, the presumed spawning season. The visceral mass (gut and gonad) as a proportion of whole mass (visceral index, %) was significantly higher in abalone fed the S-diet (RM-ANOVA; F ₍₁, ₆₉₎ = 68.06, p < 0.0001). There was no difference in meat mass index (%) between diets for both male and female abalone (RM-ANOVA; F ₍₇, ₂₄₈₎ = 0.80, p = 0.60; F ₍₇, ₂₄₁₎ = 1.7, p = 0.11,respectively). Meat mass index significantly decreased from September 2012 to February 2013 coinciding with the period of high GBI-values. The distribution of oocyte maturity stages differed between diets. The majority of oocytes within S-diet-fed abalone were fully mature stage 8 oocytes compared to a majority of stage 7 oocytes in F-diet-fed abalone. Histology corroborated peaks in GBI-values for abalone fed both diets. There was no significant difference in growth, GBI, visceral index (%) and meat mass index (%) between abalone sorted into monosex and mixed-sex populations. Thus, the presence of the opposite sex did not have an effect on growth and gonad mass in H. midae. The phytoestrogens daidzin, glycitin, genistin, daidzein, glycitein and genistein were present in soybean meal and only traceable amounts were found in the F-diet. This study provided evidence that soybean meal present in formulated feed affected growth and gonad development in H.midae. The difference in the distribution of the maturity stages of oocytes was affected by diet. Sex-sorting abalone into monosex and mixed-sex populations had no influence on weight and length gain and gonad development.
- Full Text:
Growth and gonad size in cultured South African abalone, Haliotis midae
- Authors: Riddin, Nicholas Alwyn
- Date: 2013
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- Growth -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5180 , http://hdl.handle.net/10962/d1001651 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- Growth -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Description: According to farm records, cultured Haliotis midae (50-70 g.abalone⁻¹) were growing 10% slower in winter when compared to summer. This reduction in growth rate also coincided with enlarged gonads. Initial trials showed that there were differences in mean monthly growth rates ranging from 1.97 – 5.14 g abalone⁻¹ month⁻¹, and gonad bulk index (GBI) also varied between months (GBI range: 26.88 ± 12.87 to 51.03 ± 34.47). The investment of energy into gonad tissue growth did not compromise whole body growth as the abalone continued to gain weight throughout the reproductive periods, probably due to gonadal growth. Growth of this size class of abalone was not influenced by water temperature or day length, suggesting favourable on-farm culture conditions (regression analyses, p > 0.05). There is no need to implement a seasonal dietary regime. Cultured H. midae were fed artificial diets with different protein sources, including only soya, only fishmeal, a combination of soya and fishmeal, and these were compared to kelp-fed abalone. Kelp-fed abalone grew slower than those fed artificial feeds (p>0.05). Gonad growth was the greatest when soya meal was included in the diet (average GBI: 74.91 ± 23.31), while the average gonad size of abalone fed the fishmealbased diet had gonads which were 38% smaller, and kelp-fed abalone had gonads which were 75% smaller than those of the abalone fed on diets containing soya meal. The increased gonad mass in abalone fed on diets including soya meal could be attributed to phytoestrogenic activity, as a result of the presence of isoflavones found in the soya plant; this remains to be tested. The use of soya in brood stock diet development is advised. The influence of dietary protein to energy ratio (1.41 – 2.46 g MJ⁻¹) on growth and gonad size was tested. Protein and energy levels within the ranges tested (22 and 33% protein; 13.5 and 15.6 MJ kg⁻¹) did not interact to influence growth rates of cultured H. midae. GBI increased from 50.67 ± 4.16 to 83.93 ± 9.35 units as a function of dietary protein to energy ratio (y = 42.02 x⁰·⁸¹; r² = 0.19; regression analysis: F₁¸₃₈ = 8.9; p = 0.005). In addition, protein level influenced gonad size, with gonad growth being greater in abalone fed the high protein diet (factorial ANOVA: F₁¸₃₂ = 7.1, p = 0.012). Canning yields were reduced by 7% when the protein content was increased, while increasing the quantity of dietary energy improved canning yields by ~ 6% (one-way ANOVA: F₁¸₂₈ = 14.4, p= 0.001). The present study provided evidence that although growth rates are varying seasonally, reproductive investment is not hindering weight gain. Gonad growth can be influenced if desired by farms, depending on the level of soya inclusion, as well as the protein to energy ratio in the diet. Monthly variation in growth and gonad size, as well as the influence of diet on gonad growth were highlighted, and the implications for farm application and further research were discussed.
- Full Text:
- Authors: Riddin, Nicholas Alwyn
- Date: 2013
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- Growth -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5180 , http://hdl.handle.net/10962/d1001651 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- Growth -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Description: According to farm records, cultured Haliotis midae (50-70 g.abalone⁻¹) were growing 10% slower in winter when compared to summer. This reduction in growth rate also coincided with enlarged gonads. Initial trials showed that there were differences in mean monthly growth rates ranging from 1.97 – 5.14 g abalone⁻¹ month⁻¹, and gonad bulk index (GBI) also varied between months (GBI range: 26.88 ± 12.87 to 51.03 ± 34.47). The investment of energy into gonad tissue growth did not compromise whole body growth as the abalone continued to gain weight throughout the reproductive periods, probably due to gonadal growth. Growth of this size class of abalone was not influenced by water temperature or day length, suggesting favourable on-farm culture conditions (regression analyses, p > 0.05). There is no need to implement a seasonal dietary regime. Cultured H. midae were fed artificial diets with different protein sources, including only soya, only fishmeal, a combination of soya and fishmeal, and these were compared to kelp-fed abalone. Kelp-fed abalone grew slower than those fed artificial feeds (p>0.05). Gonad growth was the greatest when soya meal was included in the diet (average GBI: 74.91 ± 23.31), while the average gonad size of abalone fed the fishmealbased diet had gonads which were 38% smaller, and kelp-fed abalone had gonads which were 75% smaller than those of the abalone fed on diets containing soya meal. The increased gonad mass in abalone fed on diets including soya meal could be attributed to phytoestrogenic activity, as a result of the presence of isoflavones found in the soya plant; this remains to be tested. The use of soya in brood stock diet development is advised. The influence of dietary protein to energy ratio (1.41 – 2.46 g MJ⁻¹) on growth and gonad size was tested. Protein and energy levels within the ranges tested (22 and 33% protein; 13.5 and 15.6 MJ kg⁻¹) did not interact to influence growth rates of cultured H. midae. GBI increased from 50.67 ± 4.16 to 83.93 ± 9.35 units as a function of dietary protein to energy ratio (y = 42.02 x⁰·⁸¹; r² = 0.19; regression analysis: F₁¸₃₈ = 8.9; p = 0.005). In addition, protein level influenced gonad size, with gonad growth being greater in abalone fed the high protein diet (factorial ANOVA: F₁¸₃₂ = 7.1, p = 0.012). Canning yields were reduced by 7% when the protein content was increased, while increasing the quantity of dietary energy improved canning yields by ~ 6% (one-way ANOVA: F₁¸₂₈ = 14.4, p= 0.001). The present study provided evidence that although growth rates are varying seasonally, reproductive investment is not hindering weight gain. Gonad growth can be influenced if desired by farms, depending on the level of soya inclusion, as well as the protein to energy ratio in the diet. Monthly variation in growth and gonad size, as well as the influence of diet on gonad growth were highlighted, and the implications for farm application and further research were discussed.
- Full Text:
Water quality dynamics in an experimental serial-use raceway and its effects on growth of South African abalone, Haliotis midae
- Authors: Naylor, Matthew Aubrey
- Date: 2012
- Subjects: Haliotis midae -- South Africa , Abalone culture -- South Africa , Abalones -- Effect of water quality on , Abalones -- Nutrition -- South Africa , Abalones -- Feeding and feeds , Abalones -- Growth , Fish culture -- Water reuse
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5335 , http://hdl.handle.net/10962/d1005181 , Haliotis midae -- South Africa , Abalone culture -- South Africa , Abalones -- Effect of water quality on , Abalones -- Nutrition -- South Africa , Abalones -- Feeding and feeds , Abalones -- Growth , Fish culture -- Water reuse
- Description: An understanding of species specific water quality requirements is essential for efficient production of aquaculture products, an aspect not well documented for the land-based culture of the South African abalone, Haliotis midae. In order for the industry to remain competitive in international markets, efficient use of water supplies and the development of water reuse technology is needed. This study assessed the changes in water quality between tanks in a tiered serial-use raceway in relation to accumulated biomass and water flow and estimated the flow index (FI) (L h⁻¹ kg⁻¹) at which growth becomes significantly affected. The effect of dietary protein level, supplementation of pure oxygen and addition of sodium hydroxide (NaOH⁻) on water quality and fundamental production parameters in the serial-use raceways was also assessed. The serial-use raceways were used as a tool to create a range of water quality conditions at which the growth, feed conversion ratio (FCR) and condition factor (CF) of "cocktail" size (60 – 70 mm) H. midae could be monitored. The metabolic activity of the abalone resulted in a deterioration in water quality between tanks in series. pH (r² = 0.99; p < 0.001) and dissolved oxygen concentration (r² = 0.99; p < 0.001) were positively correlated with flow index (pH = 7.38 FI°·°² ; dissolved oxygen = 6.92 FI°·°⁴), while free ammonia nitrogen (FAN) (r² = 0.99, p < 0.001) and nitrite (NO²⁻ - N) (r² = 0.93, p < 0.001) were negatively correlated with flow index (FAN = 8.02 FI⁻°·⁷¹). Nitrite concentrations increased over time indicating colonisation of Nitrosomonas bacteria on the basket surfaces. A flow index of 7.2 – 9.0 L h⁻¹ kg⁻¹ was estimated as the minimum to avoid significant reductions in weight and shell length gain and increases in FCR values. Total ammonia nitrogen (TAN) and FAN concentrations were significantly correlated to dietary protein (P) (t = 6.63, p < 0.0001 and t = 6.41, p < 0.0001, respectively) and flow index (t = 5.42, p < 0.0001 and t = 3.9, p < 0.0002, respectively) and could be estimated using the models TAN = 9.73 P – 110.3 log (FI), and FAN = 0.132 P – 1.10 log (FI). Mean FAN concentrations were 67 and 41 % lower in tanks fed a diet containing 22 and 26 % protein respectively, when compared to tanks fed a 33 % protein diet. Supplementation with pure oxygen (103 ± 8 % saturation) improved shell length gain (t = 3.45, p = 0.026) in abalone exposed to high FAN (2.43 ± 1.1 μg L⁻¹) and low pH (7.6 ± 0.13), relative to a treatment with no oxygen supplementation (92 ± 6 % saturation). Addition of a sodium hydroxide solution resulted in elevated mean pH in treatment raceways when compared to control raceways. The increased pH resulted in significantly higher weight gain (g abalone⁻¹) (F₁·₁₂ = 4.51; p = 0.055) and shell length gain (mm abalone⁻¹) (F₁·₁₂ = 4.56; p = 0.054) at an α-error level of < 5.5 %. In two trials, weight gain and shell length gain were significantly correlated to pH (p < 0.001), and multiple regression of pH, dissolved oxygen and FAN consistently revealed pH to be the best predictor of growth. It is therefore suggested that decreasing pH is the first limiting water quality variable for abalone in serial-use raceways. As a decrease in water pH is linked to respiration by the abalone and subsequent increase in dissolved carbon dioxide (CO₂) concentration, future studies should examine the effects of CO₂ on H. midae metabolic rate, calcification rate and health. The results of this study will contribute toward our understanding of the specific water quality requirements for H. midae in commercial aquaculture systems, and influence the design and management procedures for abalone water reuse systems.
- Full Text:
- Authors: Naylor, Matthew Aubrey
- Date: 2012
- Subjects: Haliotis midae -- South Africa , Abalone culture -- South Africa , Abalones -- Effect of water quality on , Abalones -- Nutrition -- South Africa , Abalones -- Feeding and feeds , Abalones -- Growth , Fish culture -- Water reuse
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5335 , http://hdl.handle.net/10962/d1005181 , Haliotis midae -- South Africa , Abalone culture -- South Africa , Abalones -- Effect of water quality on , Abalones -- Nutrition -- South Africa , Abalones -- Feeding and feeds , Abalones -- Growth , Fish culture -- Water reuse
- Description: An understanding of species specific water quality requirements is essential for efficient production of aquaculture products, an aspect not well documented for the land-based culture of the South African abalone, Haliotis midae. In order for the industry to remain competitive in international markets, efficient use of water supplies and the development of water reuse technology is needed. This study assessed the changes in water quality between tanks in a tiered serial-use raceway in relation to accumulated biomass and water flow and estimated the flow index (FI) (L h⁻¹ kg⁻¹) at which growth becomes significantly affected. The effect of dietary protein level, supplementation of pure oxygen and addition of sodium hydroxide (NaOH⁻) on water quality and fundamental production parameters in the serial-use raceways was also assessed. The serial-use raceways were used as a tool to create a range of water quality conditions at which the growth, feed conversion ratio (FCR) and condition factor (CF) of "cocktail" size (60 – 70 mm) H. midae could be monitored. The metabolic activity of the abalone resulted in a deterioration in water quality between tanks in series. pH (r² = 0.99; p < 0.001) and dissolved oxygen concentration (r² = 0.99; p < 0.001) were positively correlated with flow index (pH = 7.38 FI°·°² ; dissolved oxygen = 6.92 FI°·°⁴), while free ammonia nitrogen (FAN) (r² = 0.99, p < 0.001) and nitrite (NO²⁻ - N) (r² = 0.93, p < 0.001) were negatively correlated with flow index (FAN = 8.02 FI⁻°·⁷¹). Nitrite concentrations increased over time indicating colonisation of Nitrosomonas bacteria on the basket surfaces. A flow index of 7.2 – 9.0 L h⁻¹ kg⁻¹ was estimated as the minimum to avoid significant reductions in weight and shell length gain and increases in FCR values. Total ammonia nitrogen (TAN) and FAN concentrations were significantly correlated to dietary protein (P) (t = 6.63, p < 0.0001 and t = 6.41, p < 0.0001, respectively) and flow index (t = 5.42, p < 0.0001 and t = 3.9, p < 0.0002, respectively) and could be estimated using the models TAN = 9.73 P – 110.3 log (FI), and FAN = 0.132 P – 1.10 log (FI). Mean FAN concentrations were 67 and 41 % lower in tanks fed a diet containing 22 and 26 % protein respectively, when compared to tanks fed a 33 % protein diet. Supplementation with pure oxygen (103 ± 8 % saturation) improved shell length gain (t = 3.45, p = 0.026) in abalone exposed to high FAN (2.43 ± 1.1 μg L⁻¹) and low pH (7.6 ± 0.13), relative to a treatment with no oxygen supplementation (92 ± 6 % saturation). Addition of a sodium hydroxide solution resulted in elevated mean pH in treatment raceways when compared to control raceways. The increased pH resulted in significantly higher weight gain (g abalone⁻¹) (F₁·₁₂ = 4.51; p = 0.055) and shell length gain (mm abalone⁻¹) (F₁·₁₂ = 4.56; p = 0.054) at an α-error level of < 5.5 %. In two trials, weight gain and shell length gain were significantly correlated to pH (p < 0.001), and multiple regression of pH, dissolved oxygen and FAN consistently revealed pH to be the best predictor of growth. It is therefore suggested that decreasing pH is the first limiting water quality variable for abalone in serial-use raceways. As a decrease in water pH is linked to respiration by the abalone and subsequent increase in dissolved carbon dioxide (CO₂) concentration, future studies should examine the effects of CO₂ on H. midae metabolic rate, calcification rate and health. The results of this study will contribute toward our understanding of the specific water quality requirements for H. midae in commercial aquaculture systems, and influence the design and management procedures for abalone water reuse systems.
- Full Text:
- «
- ‹
- 1
- ›
- »