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The present study investigated the effects of short-chain fructooligosaccharides (FOS) as dietary supplements on stress, immune response, gut microbiota, growth, and survivability of three different treatment groups of Pacific white shrimp, Litopaneous vennamei, cultured in a recirculating system. The experiment was conducted over a 35-day trial period. Shrimps were fed diets, 15 times a day using automated feeder, supplemented with GOS at 0%, 0.15%, and 0.30% by weight. Denaturing gradient gel electrophoresis analysis revealed that the enteric microbial community of shrimp fed the basal diet differed markedly (<80.0% similarity coefficient) from those fed FOS-supplemented diets. However, shrimp survival, weight gain, and immune responses among the treatment groups were good but not significantly different (P > 0.05), probably due to the limited length of the feeding trial. [ABSTRACT FROM AUTHOR]

This study was designed to examine the effects of a prebiotic compound on the immune system, digestive tract histology, and stress physiology of shrimp. The specific effects of dietary supplementation of the prebiotic galactooligosaccharide (GOS or GTGOS) on shrimp health are scarce. This experiment, therefore attempted to evaluate the effects of GOS on growth, survival, intestinal microbiota, stress resistance and immune responses of Pacific white shrimp, Litopaneous vannamei. Over a 35-day trial, shrimps were fed diets, 15 times a day using automated feeder, supplemented with GOS at 0%, 0.25%, and 0.40% by weight. Shrimp survival and weight gain among the treatment groups were good but not significantly different (P >.05). Shrimp fed GOS-supplemented diets had reduced stress (glucose, P <.05) and increased immune responses (total hemocyte counts and phagocytic capacity, P <.05) compared to shrimps fed only basal diet with no supplementation. These results suggest that GOS not only changed the populations of gut microbiota but also reduced stress levels and enhanced immune response in shrimp. [ABSTRACT FROM AUTHOR]

Abstract: Channel catfish was used to investigate the enhancement of vaccine efficacy following dietary supplementation with arginine (ARG, 4% of diet), glutamine (GLN, 2% of diet), or a combination of both. After vaccination against Edwardsiella ictaluri, humoral and cellular immune responses, along with lymphoid organ responses were evaluated. E. ictaluri-specific antibody titers in plasma were higher (P < 0.05) in fish fed the supplemented diets compared to those fed the basal diet as early as 7 d post-vaccination (dpv). B-cell proportion in head-kidney was higher (P < 0.05) at 14 dpv in vaccinated fish fed the GLN diet. The responsiveness of spleen and head-kidney lymphocytes against E. ictaluri was enhanced (P < 0.05) by dietary supplementation of ARG or GLN at 14 dpv. Additionally, at 7 dpv, vaccinated fish fed the GLN diet had higher (P < 0.05) head kidney weights relative to the other dietary treatments, and vaccinated fish fed ARG-supplemented diets had higher (P < 0.05) protein content in this tissue. Results from this study suggest that dietary supplementation of ARG and GLN may improve specific cellular and humoral mechanisms, enhancing the acquired immunity in vaccinated channel catfish. [Copyright &y& Elsevier]

Abstract: Both arginine and glutamine play important roles in tissue repair, cell replication and collagen synthesis which impact animal growth and survival. Thus, a 7-week feeding trial was conducted to determine the effects of dietary arginine and glutamine on growth performance, innate immune responses and intestinal structure of juvenile red drum, Sciaenops ocellatus (6.9±0.04g, initial average weight). Protein in all experimental diets was derived from menhaden fishmeal and dehulled, solvent-extracted soybean meal to provide isonitrogenous (44% crude protein) and isolipidic (10%) diets. The basal diet contained 0.14% glutamine and 1.72% arginine on a dry-matter basis, which exceeds the established dietary requirement of red drum. Experimental diets were prepared by supplementing the basal diet with either arginine at 1% of dry weight, glutamine at 1%, glutamine at 2%, or both arginine and glutamine at 1%, with adjustments in glycine to maintain equal nitrogen among all diets. Feed efficiency was significantly (P <0.05) improved by supplementation of glutamine at 2% and the combination of both arginine and glutamine at 1% of diet. Neutrophil oxidative radical production in fish fed the glutamine and/or arginine-supplemented diets was significantly (P =0.03) higher compared with that of fish fed the basal diet, with a synergistic effect observed in fish fed the combined arginine–glutamine diet. Significantly (P <0.05) higher serum lysozyme activity also was observed in fish fed the diet supplemented with 1% of both arginine and glutamine. Extracellular superoxide anion production by red drum macrophages was significantly (P <0.05) higher for fish fed diets with glutamine at either 1 or 2% and the 1% arginine–glutamine combination compared to fish fed the basal diet. Similarly, macrophages from fish fed the diet with glutamine at 2% and the arginine–glutamine combination at 1% produced significantly higher amounts of intracellular superoxide anion. Morphometric analyses – i.e., measurements of enterocyte, microvillus and fold heights – demonstrated positive effects of both dietary glutamine and arginine in different portions (proximal, mid and distal) of the gastrointestinal tract of red drum. In general, fish fed the diet supplemented with 2% glutamine had the greatest increases in magnitude of the chosen structures, although those fed the diet with arginine at 1% also yielded improved scores for some enteric portions. Therefore, results from the present study establish the importance of both dietary arginine and glutamine supplementation in improving feed efficiency, as well as eliciting positive changes to several components of the innate immune system and intestinal functionality of red drum. [Copyright &y& Elsevier]

Abstract: Dietary nucleotides have been shown to benefit many physiological and nutritional functions in higher vertebrates and fish. Therefore, a 6-week feeding trial was conducted to evaluate the effects of graded levels of a commercial nucleotide product on growth performance, immune responses and intestinal morphology of juvenile red drum (initial average weight of 7.1g). The basal diet was formulated to contain 40% protein, 10% lipid and a digestible energy level of 3.5kcalg−1. Two levels of nucleotide (Ascogen P®, 0.5% and 1% of diet) were added to the basal diet with menhaden fishmeal and menhaden oil adjusted to provide isonitrogenous and isolipidic diets. Nucleotide supplementation tended to improve weight gain and survival of red drum, but not at a significant level. Neutrophil oxidative radical anion production and serum lysozyme activity tended to be higher for fish fed diets supplemented with nucleotide, while extracellular superoxide anion production of head kidney macrophages from fish fed diets with 1% nucleotide was significantly (P <0.05) increased, although no significant differences were observed between fish fed 0.5% nucleotide diet and the basal diet. Nucleotide supplementation significantly (P <0.05) increased fold height in the proximal intestine, and enterocyte height in the pyloric caeca, proximal and distal enteric sections. A significantly (P <0.05) higher microvilli height was observed in all evaluated enteric sections of fish fed with diets supplemented with nucleotides. It is therefore possible to use dietary nucleotides supplementation to significantly enhance the intestinal structure of red drum. Likewise, nucleotides in the diet may improve some components of the non-specific immune response of this sciaenid fish. [ABSTRACT FROM AUTHOR]

Abstract: Various studies with fish species indicate that dietary arginine (Arg) and glutamine (Gln) supplementation may support an enhanced performance beyond simply improving weight gain. Therefore, a feeding trial was conducted to determine the effects of dietary Arg or Gln on growth performance, immune responses and intestinal morphology of juvenile hybrid striped bass, Morone chrysops × Morone saxatilis (4.1±0.02g, initial average weight). The basal diet was formulated from menhaden fishmeal and solvent-extracted soybean meal to contain 45% crude protein and 10% lipid. Arginine and Gln were singularly added to the basal diet at either 1% or 2% or both amino acids were added in combination at 1% to formulate experimental diets with adjustments in glycine to maintain all diets iso-nitrogenous. Fish were fed the experimental diets for a period of 8weeks, at the end of which final weight, specific growth rate and feed efficiency were significantly (P <0.05) higher in fish fed diets supplemented with Arg at either 1 or 2%, Gln at 1%, Arg and Gln both at 1%, but not in those fed the diet supplemented with Gln at 2%. Arginine and/or Gln supplementation tended to improve neutrophil oxidative radical production, but not significantly (P >0.05). However, significantly higher serum lysozyme activity was observed in fish fed the diet supplemented with Arg at either 1 or 2% and Gln at 1%. Intracellular superoxide anion production by hybrid striped bass macrophages also tended to increase, while extracellular superoxide anion production was significantly improved by supplementation of Arg at 1% and Gln at either 1 or 2% of diet. Morphometric analyses demonstrated positive effects of both dietary Arg and Gln on histo-morphological measurements in different portions of the gastrointestinal tract of hybrid striped bass. The 1% Arg diet resulted in the greatest increases in size of the chosen enteric structures, but the other four experimental diets also significantly improved the scores for various intestinal portions compared to fish fed the basal diet. Results from the present experiment demonstrate the importance of dietary supplementation of both Arg and Gln in improving growth performance, eliciting positive changes to several components of the innate immune system, and also benefiting the intestinal functionality of hybrid striped bass. [Copyright &y& Elsevier]