Aspects of the nutritional physiology of the perlemoen Haliotis midae (L.) and red abalone H. rufescens (Swainson)
- Authors: Kemp, Justin Oliver Gordon
- Date: 2018
- Subjects: Haliotis midae , Haliotis midae fisheries , Red abalone , Haliotis midae -- Feeding and feeds , Red abalone -- Feeding and feeds , Haliotis midae -- Nutrition -- Requirements , Red abalone -- Nutrition -- Requirements , Haliotis midae -- Metabolism , Red abalone -- Metabolism , Haliotis midae -- Physiology , Red abalone -- Physiology , Stable isotopes , Algae as feed
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62314 , vital:28154
- Description: The source of abalone for human consumption has shown a dramatic shift away from wild-capture fisheries in the last 30 years, with over 90% of global production now coming from aquaculture. Farmers initially relied on the natural food of abalone (macroalgae) as a culture feed, though in regions where macroalgae availability was limiting, the need to develop formulated feeds was evident. Extensive research effort has led to the development of a number of formulated feed products currently employed in the industry. These feeds, however, differ markedly from the mixed macroalgal diets that abalone have evolved to utilise, particularly in terms of protein content and carbohydrate structure. The degree to which the nutritional physiology of abalone responds to these novel formulated diets, with and without macroalgal supplementation, was investigated in the current study. A multifaceted approach, combining growth trials, stable isotope nutrient tracers and metabolic experiments, was employed to gain insight into the post-absorption dynamics and utilisation of dietary nutrients under varying dietary regimes of fresh macroalgae and formulated feed. Growth trials conducted with both Haliotis rufescens and H. midae showed significantly higher growth and protein utilisation efficiency for abalone fed macroalgal diets compared to formulated feeds. Furthermore, when formulated feeds were supplemented with macroalgae to form combination diets, growth and the utilization of protein was improved compared to the formulated-feed-only diet. The poor utilisation of protein by H. midae fed the formulated feed could be traced, using a method combining stable isotope bio-markers with a Bayesian mixing model (SIAR), to the low incorporation of the fishmeal component of protein in the diet. The marked postprandial drop in the O:N ratio on abalone fed formulated feeds indicate that the protein was being diverted into catabolic metabolic pathways. The metabolic cost of digestion, termed specific dynamic action (SDA), was negated as a factor in the improved growth of abalone fed macroalgal diets, with the SDA coefficient 2.1 times that observed for formulated feed. Furthermore, the postprandial haemolymph glucose concentration (HGC) in H. midae was elevated when fed formulated feed compared to macroalgae. The high levels of circulating glucose are likely a result of the structure the carbohydrate source in formulated feeds and stimulate the deposition of glycogen through the allosteric control of glycogen synthase. Formulated feeds produced higher cooked meat yields in canning simulation trials, suggesting that muscle glycogen content may indirectly play a role in increasing canning yields through the displacement of collagen. The results of these empirical studies are synthesised under key themes, discussed within the context of their potential commercial relevance and future research directions are highlighted.
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The effects of dietary soya and crystalline phytoestrogens on the growth, gonad development and histology of farmed abalone, Haliotis midae
- Authors: Wu, Yu
- Date: 2015
- Subjects: Haliotis midae , Haliotis midae -- Feeding and feeds , Haliotis midae -- Growth , Haliotis midae -- Histology , Haliotis midae -- Effect of chemicals on , Soybean as feed , Phytoestrogens
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5380 , http://hdl.handle.net/10962/d1017225
- Description: The inclusion of soya as a dietary protein source in the formulated feed, Abfeed® S34 (Marifeed Pty (Ltd), Hermanus) for farmed abalone, Haliotis midae has resulted in larger gonads during reproductive seasons compared to the gonads of abalone fed kelp or diets that included fishmeal as the only main protein source. The aim of this study was to determine if the isoflavones present in the soya were responsible for this increase in gonad size and the subsequent effects on farmed abalone growth. Animals weighing between 40-50 g were fed one of seven isonitrogenous and isoenergetic diets containing either 0, 25, 50 or 100 percent of the soya component of the commercial feed (Abfeed® S34, Marifeed Pty (Ltd), Hermanus) from September 2013 to March 2014. An additional three diets were formulated to include crystalline isoflavone (ISO). These diets were identical to the 0 percent soya diet (i.e. the fishmeal only diet - FM), only ISO was included at the same rate that ISO occurred in the three soya diets. Data were analysed using a multiple forward stepwise regression analysis (MSR) to test the effects of ISO concentration, soya concentration, time, sex, time by concentration interaction and sex by concentration interaction on growth and gonad development and to identify those variables that most contributed to the model. The inclusion of crystalline ISO failed to promote larger gonads and had no effect on abalone growth, while growth and gonad development was dose dependent on soya inclusion rates with sex and time contributing to the models. Mean monthly weight gain in males correlated with increasing soya concentrations (c) (MSR, y = 3.24 + 0.002c, r2 = 0.23, p = 0.03), ranging from 3.11 ± 0.55 g abalone-1 month-1 to 4.43 ± 0.46 g abalone-1 month-1, while both male and female monthly length gain was not influenced by soya concentration with an overall mean of 1.62 ± 0.05 mm abalone-1 month-1 (MSR, p = 0.05 and p = 0.81, respectively). By December, the whole body mass, meat mass and visceral mass in both males and females decreased with increasing soya levels. However, by February, female whole body mass, meat mass and visceral mass positively correlated with soya levels. At the end of the study, male abalone fed FM with soya equivalent to the commercial feed had the highest whole body mass (69.00 ± 2.48 g abalone-1), meat mass (41.80 ± 1.12 g abalone-1), visceral mass (9.00 ± 2.47 g abalone-1) and gonad bulk index (42.70 ± 9.82 g abalone-1), while females were not influenced by soya concentrations with an overall whole body mass of 63.46 ± 0.79 g abalone-1. Weight loss was observed in all treatments between February and March, probably due to a spawning event. The moisture content in the meat was not influenced by treatment, however, visceral water loss was effected by both ISO and soya concentration with time and sex contributing to the model. The visceral water loss of females fed graded levels of soya decreased as a function of soya from December to March, and from December to February for males, whereas females fed ISO-enriched diets decreased as a function of ISO concentration (c) at the end of the study from 74.98 ± 0.88 to 73.10 ± 0.75 percent (MSR, y = 74.97 – 0.0025c, r2 = 0.20, p = 0.048). The inclusion of crystalline ISO had no significant effect on oogenesis in female farmed Haliotis midae, while the distribution of the predominant oocyte stage, stage 7 (second last stage prior to spawning) was dose-dependent in abalone fed increasing soya concentration (c) (MSR, y = 33.38 + 0.03c, r2 = 0.32, F(1, 18) = 8.52, p = 0.01). The increase in stage 7 oocytes in abalone fed FM with soya did not reduce the number of oocytes (44.96 ± 3.01 oocytes mm-2) present within the lumen, while the number of oocytes (o) in abalone fed the FM-only based diets decreased with increasing abundance of stage 7 oocytes (MSR, y = 58.28 – 0.48c, r2 = 0.38, F(1, 18) = 12.51, p = 0.002), possibly due to the increase in size of the oocytes with thicker jelly coats. This study provided evidence that crystalline isoflavone had no influence on abalone gonad development over five months, while soya had a dose-dependent effect on growth, gonad mass and oogenesis in farmed Haliotis midae. Formulated abalone feed could be manipulated at certain times of the year to obtain maximum growth. These implications and further studies were discussed.
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The use of probiotics in the diet of farmed South African abalone Haliotis midae L
- Authors: Maliza, Siyabonga
- Date: 2015
- Subjects: Haliotis midae -- South Africa , Abalones -- South Africa , Haliotis midae -- Feeding and feeds , Haliotis midae -- Effect of chemicals on , Haliotis midae -- Growth , Haliotis midae -- Immunology , Probiotics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5382 , http://hdl.handle.net/10962/d1018178
- Description: Physiological stress in farmed abalone can lead to immunosuppression and increase the susceptibility to bacterial, viral and parasitic disease, often followed by mortality. Thus, handling and poor water quality can reduce farm production efficiency. Probiotics in aquaculture have been effective in a wide range of species in enhancing immunity, survival, improving feed utilisation and growth. Three putative probionts identified as a result of in vitro screening had been beneficial to laboratory-reared abalone in a previous study. The aim of this study was to produce an abalone feed that contains a suite of probionts that may promote abalone growth and health under farming conditions. The objectives were to compare growth and physiological responses (i.e., haemocyte and phagocytosis counts) of abalone fed a commercial feed (Abfeed®S 34, Marifeed, Hermanus) supplemented with probiotics (i.e., the probiotic diet) to abalone fed the commercial feed without probiotic supplementation as a control treatment in a factorial design with handling method as an independent variable. This experiment was conducted at HIK Abalone Farm (Pty Ltd) for a period of eight months with initial weight and length 36.1 ± 0.05 g and 58.6 ± 0.06 mm abalone-1. Another experiment was carried out at Roman Bay Sea Farm (Pty) Ltd with initial weight and length 34.7 ± 0.17 g and 62.3 ± 0.18 mm abalone-1, but this experiment included one factor only, i.e. the presence and absence of the probionts in the feed. At HIK there was no significant interaction between diet and handling on average length and weight gain month-1 after four (p=0.81 and p=0.32) and eight (p=0.51 and p=0.53) months, respectively. Average length (additional handling = 73.9 ± 0.52 mm, normal farm handling = 75.8 ± 0.57 mm) and weight gain (mean: additional handling = 68.5 ± 1.20 g, normal farm handling = 74.3 ± 1.86 g) increased significantly in animals that were handled under normal farm procedure and were either fed probiotic or control diet after eight months (p=0.03 and p=0.02, respectively). There was no iii difference in length gain or weight gain of abalone fed the probiotic diet and those fed the control diet (ANOVA: F(1,16)=0.04, p=0.84; F(1,16)=0.14, p=0.71, respectively). After four months phagocytotic count was significantly different between dietary treatments with mean values of 74.50 ± 10.52 and 63.52 ± 14.52 % phagocytosis count per sample for the probionts and control treatment, respectively (p=0.04), there was no difference after eight months at HIK Abalone Farm. There was no effect of stressor application (p=0.14) and no interaction between dietary treatment and stressor application for this variable i.e., phagocytosis count (p=0.61). There was no difference in feed conversion ratio between treatments with values ranging from 2.9 to 3.8. At Roman Bay Sea farm, there was no significant difference in mean length gain between abalone fed the probiotic and control diet after eight months (repeated measures ANOVA: F(4,28)=16.54. Mean weight gain of abalone fed the probiotic diet was significantly greater than those fed the control diet after eight months (repeated measures ANOVA: F(4,28)=39.82, p(0.00001). There was no significant difference in haemocyte counts between animals fed either probiotic or control diet after four and eight months at Roman Bay Sea farm (p>0.05).
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