An 8-week feeding trial was conducted to evaluate the effects of dietary γ-aminobutyric acid (GABA) on growth performance, immune response, and disease resistance for juvenile whiteleg shrimp, Litopenaeus vannamei. Five isonitrogenous diets were formulated by supplementing 0 (CON), 50 (GABA50), 100 (GABA100), and 300 (GABA300) mg of GABA and 4 g of oxytetracycline (OTC) per kilogram of diet. A total of 225 juvenile whiteleg shrimp with an initial weight of 2.97 ± 0.06 g were randomly distributed and reared in 15 aquaria as triplicates. After 8 weeks of the feeding trial, weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of shrimp fed GABA100 were significantly higher than those of shrimp fed CON, GABA50, and GABA300 diets ( P < 0.05 ). However, there were no significant differences among shrimp fed CON, GABA50, GABA300, and OTC diets ( P > 0.05 ). After nine days of challenge test with Vibrio alginolyticus, the average cumulative survival rate of shrimp fed GABA50, GABA100, and OTC was significantly higher than that of shrimp fed GABA300 and CON diets ( P < 0.05 ). These results may suggest that 100 mg dietary GABA supplementation (including endogenous GABA, 175.6 mg/kg diet) per kilogram of diet could be the optimum dietary level to replace antibiotics and improve growth performance and disease resistance in whiteleg shrimp L. vannamei.
Shrimp farming is a key component of Vietnamese aquaculture contributing ~5% to their gross domestic product annually. Environmental hazards and socio‐economic parameters among other factors influence shrimp productivity in Vietnam. The present study employed the stochastic frontier production approach to investigate how technical efficiency (TE) of semi‐intensive and intensive shrimp farms is influenced by socio‐economic factors and environmental hazards. A questionnaire was administered to ascertain farmers' cost of major inputs (labour, seed, feed and lime), socio‐economic factors, coupled with environmental hazards (flood, pollution and drought experience). Findings revealed a mean TE of approximately 65% and 76% for semi‐intensive and intensive farms respectively (though, non‐significant as p ≥ 0.05). The input variables, shrimp seeds, feed and lime were found to be important variables in the intensive systems, as they positively correlated with TE in intensive systems. In the inefficiency model, education positively correlated with the TE in both systems, indicating that educated farmers are more efficient. Pollution negatively correlated with TE in both systems. With <80% of the farmers extremely affected by floods and droughts, and about 95% affected by pollution, the present study concludes there is a thorough impact of the above environmental hazards on farmers' technical efficiency.
The food and feeding habits of eight (8) fish species Elops lacerta, Chrysichthys auratus, Schilbe mys-tus, Sardinella maderensis, Synodontis schall, Hepsetus odoe, Tilapia zillii and Mugil cephalus in Ogun estuary, Ogun State, Nigeria were studied and estimated for six months, between February and July, 2014. A total of 470 fishes were randomly collected from the commercial fishermen during the study. Results from the stomach contents analysed using frequency of occurrence and numerical methods showed that S. mystus, E. lacerta, S. maderensis, H. odoe, S. schall, T. zillii, M. cephalus and C. auratus were predators, piscivores, herbivores, piscivores, omnivores, herbivores, herbivores and omnivores respectively while H. odoe and S.mystus partly fed on E. lacerta and T. zillii respec-tively. The Diet Breadth (D) ranged from 0.76 to 0.88 and the percentage Gut Repletion Index (GRI), a reflection of frequency of feeding, ranged between 60-100%.
Protein is an essential nutrient that supports fish growth, and the inadequacy in formulating their diets with an optimum protein level can deteriorate their growth performance. The protein requirement in granulated microdiets was estimated for rockfish (Sebastes schlegeli) larvae. Five granulated microdiets (CP42, CP46, CP50, CP54, and CP58) containing 42% to 58% crude protein levels with a 4% increment at a constant gross energy level (18.4 kJ/g diets) were prepared. The formulated microdiets were also compared with imported microdiets, Inve (IV) and love larva (LL) from Belgium and Japan, respectively, and a locally marketed feed (crumble). At the cessation of the study, the survival of larval fish was not different ( P > 0.05 ), but the weight gain (%) of fish fed the CP54, IV, and LL diets was significantly ( P < 0.0001 ) higher than that of larval fish fed the CP58, CP50, CP46, and CP42 diets. The crumble diet achieved the poorest weight gain of larval fish. Furthermore, the total length of rockfish larvae fed the IV and LL diets was significantly ( P < 0.0001 ) longer than that of the fish fed all other diets. The chemical composition of the fish’s whole body, except for ash content, was not influenced by the experimental diets. The experimental diets affected essential amino acid profiles, such as histidine, leucine, and threonine, and nonessential amino acid profiles, such as alanine, glutamic acid, and proline of the whole body of larval fish. Conclusively, based on the broken line analysis of weight gain of larval rockfish, protein requirement in granulated microdiets was estimated to be 54.0%.
Feed additives are essential in improving the growth and immunity of eels, which are often affected by nutritional and disease challenges. This study evaluated the effects of two dietary synbiotics in Japanese eel, Anguilla japonica: Bacillus subtilis with mannooligosaccharide (MOS) and Enterococcus faecium with fructooligosaccharide (FOS). Six diets, including a basal diet (CON), a 4 g kg− 1 oxytetracycline (OTC), and four synbiotic diets - B.subtilis at 1 × 106 and 107 CFU g− 1 plus 5 g kg− 1 MOS (BS6MO and BS7MO) and E. faecium at 1 × 106 and 107 CFU g− 1 plus 5 g kg− 1 FOS (EF6FO and EF7FO) - were prepared and fed to triplicate groups of 20 fish averaging 6.00 ± 0.07g (mean ± SD) for eight weeks. Weight gain (WG) and specific growth rate (SGR), and feed efficiency (FE) of fish fed B. subtilis plus MOS (BSMOS) diets were significantly higher than those of fish fed CON and OTC diets (p < 0.05) but not significantly higher than those of fish fed the E. faecium plus FOS (EFFOS) diets. Best protein efficiency was achieved in fish fed the synbiotics diets (p < 0.05). Fish fed OTC diets showed the highest level of aspartate aminotransferase (AST) but were not significantly different from synbiotic diets, except for BS6MO. Fish fed the EF7FO diets showed the lowest superoxide dismutase (SOD) activity compared to other synbiotics. Japanese eel fed with the synbiotic and OTC diets showed no significant difference in resistance against Vibrio anguillarum. Since synbiotics are dose dependent, the synergetic efficiency of EFFOS is better at 107 CFU g− 1. These results suggest that BS7MO may be more effective as a synbiotic in Japanese eel diet than EFFOS diets. Our results showed that synbiotic diets could improve growth and immunity and be a sustainable alternative to antibiotics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.