Search

Two feeding trials were conducted to evaluate the effects of dietary supplementation with the prebiotic GroBiotic-A on juvenile Nile tilapia, Oreochromis niloticus. Juvenile fish in both trials received a basal diet composed of practical and semipurified ingredients or the basal diet supplemented with GroBiotic-A at either 1 or 2% of dry weight. Trial 1 (8 wk), was conducted with juvenile fish initially averaging 4.3 g/fish in which their performance indices, nonspecific humoral and cellular immune responses, and intestinal microbiota were characterized. In that trial, only survival was significantly affected by dietary treatment with the greatest survival (98.7%) observed for fish fed the diet containing 2% GroBiotic-A and significantly ( P < 0.05) lower survival (86.9%) for fish fed the diet containing 1% GroBiotic-A ( GBA) and intermediate survival (90.7%) for fish fed the basal diet. Trial 2 (5 wk), was conducted with larger juveniles initially averaging 6.5 g/fish to provide a more in-depth assessment of cellular immune responses, intestinal morphometric characteristics, and disease resistance of tilapia fed the three experimental diets. Fish fed the diet with 2% GroBiotic-A exhibited significantly ( P < 0.05) increased production of extracellular superoxide anion by macrophages and a distinct microbial community within the intestine compared to fish fed the other diets. No significant differences were seen in survival after controlled exposure to Streptococcus iniae although fish fed the diet with 2% GBA tended to experience reduced mortality (12.5%) compared to those fed the basal diet (35%). Thus, based on the results from both trials, supplementation of 2% GroBiotic-A generally improved survival, altered gut microbiota, and enhanced extracellular superoxide anion production of Nile tilapia. [ABSTRACT FROM AUTHOR]

Fishmeal (FM) replacement in diets for intensive aquaculture has become a high priority area for the global aquaculture industry. In this study, a twelve week growth trial was conducted with juvenile cobia (18 g initial weight) to examine the effects of non-genetically modified soybean meals as potential replacement protein sources. Genetically modified (GM) crops and their intended and unintended effects have become major topics of controversy worldwide, with several regions banning their use in food and feeds. Therefore, it is especially critical to develop and evaluate non-GM feedstuffs for use in aquaculture diets where GM products are prohibited as the global aquaculture industry continues its expansion to meet increasing demands. Navita Premium Feed Ingredients (NPFI's) 3010 solvent extracted meal and 3032 cold-pressed cake meal were utilized to replace 50, 60 or 70% and 40, 50, or 60% of FM protein, respectively and were compared to a FM based reference formulation. None of the experimental diets performed significantly different from the reference diet in terms of weight gain (WG) or specific growth rate (SGR). However the 3010 50% diet performed significantly better than the 3032 50 and 60% diets in regard to WG, SGR, and protein efficiency. There were no significant differences between the seven diets at the conclusion of the trial in regard to their effects on filet quality as determined by organoleptic testing. These two non-GM soybean protein sources appear to be valuable FM replacement options for juvenile cobia, with none of the typical indicators of intestinal enteritis developing as has been observed in various other teleost species when high quantities of commodity soybean meal have been utilized. [ABSTRACT FROM AUTHOR]

Juvenile channel catfish Ictalurus punctatus were fed casein-gelatin-based semi-purified test diets with graded amounts of arginine ( ARG, 0.5%, 1%, 2% and 4% of dry diet) for a 6-week period, to evaluate the effects of dietary ARG supplementation on performance indicators, levels of plasma ARG, ornithine, citrulline, glutamine and glutamate, as well as selected innate immune parameters. Incremental dietary ARG resulted in significant improvements in weight gain, feed efficiency and protein efficiency ratios, protein retention, protein deposition and arginine deposition. Fish fed the 4% ARG diet had significantly higher values for all performance indicators, although these values were not different from those of fish fed the 2% ARG diet with the exception of protein retention, protein deposition and arginine deposition. Conversely, fish fed the 0.5% ARG diet had significantly lower values for all analysed plasma amino acids. Similarly, both phagocyte superoxide anion production and neutrophil respiratory burst were significantly decreased in fish fed the 0.5% ARG diet. These results demonstrate that the indispensability of dietary ARG is not only related to optimized protein utilization for growth but also its supplementation to fish diets may significantly impact several aspects of the immune system, including phagocyte function and thus improve overall fish health. [ABSTRACT FROM AUTHOR]

Abstract: The present experiment was conducted to investigate the effects of graded amounts of dietary GLN on the intestinal morphology, plasma amino acids and growth performance of juvenile channel catfish. Six experimental diets (280gkg−1 crude protein, 80gkg−1 lipid) were composed of casein, gelatin and crystalline amino acids and supplemented with 0, 5, 10, 15, 20 or 30g free glutamine kg−1. These diets were fed to triplicate groups of fish (average initial weight of 6.1) for 10weeks after which blood and intestinal samples were collected. Intestinal microstructures were positively affected by dietary GLN at the highest levels of supplementation (20 and 30gkg−1), significantly (P <0.05) increasing enterocyte and microvilli height in anterior, mid and posterior intestinal sections. Moreover, a subsequent experiment revealed that GLN supplementation significantly (P <0.05) increased the enterocyte migration rate in all sampled intestinal segments. In contrast, immunohistochemical staining of proliferating cells with mouse anti-proliferating cell nuclear antigen (PCNA), revealed an increased number of proliferating cells only at the distal intestine. Plasma amino acid levels 15h postprandial showed significantly (P <0.05) higher levels of asparagine, serine, glycine and threonine in fish fed the diet supplemented with 20g GLN kg−1 diet. Despite the consistent trend of higher values seen in fish fed the diet supplemented with 20g GLN kg−1, there were no significant (P >0.05) differences in growth-related parameters among treatments. The present results demonstrate an efficient utilization of free GLN by intestinal mucosal cells of channel catfish, which resulted in enhancement of the enteric microstructure along with increased migration rates of enterocytes and modified plasma amino acid profiles. However, these results were not translated into improved growth at the end of the 10-week feeding trial. [Copyright &y& Elsevier]

Thirty-one microsatellite markers that were previously isolated from and characterized in greater amberjacksSeriola dumeriliwere assayed for cross-species amplification in four other members of the carangid genusSeriola: the lesser amberjackS. fasciata, yellowtail jackS. lalandi, almaco jackS. rivoliana, and banded rudderfishS. zonata. The number of markers that consistently amplified and were polymorphic ranged from 16 in yellowtail jacks to 25 in lesser amberjacks. The microsatellites characterized in this study will be useful for a variety of applications, including stock structure assessments of wild fish and parentage assignments of farmed fish. Received February 7, 2012; accepted April 16, 2012 [ABSTRACT FROM PUBLISHER]

Dietary acidifiers have been recognized as beneficial in animal production including aquacultural production of fish where they confer such benefits as improved feed utilization, growth, and resistance to bacterial pathogens. If improvements in growth and immune responses by acidifier supplementation can be confirmed in shrimp, then mortalities due to diseases could be minimized, limiting the emergence of disease-resistant bacterial pathogens as a potential result of antibiotic misuse. With this in mind, a 35-d feeding trial was conducted to evaluate growth, enteric microbiota populations, and nonspecific immune responses of Litopenaeus vannamei fed diets containing the commercial acidifier Vitoxal, based on acidic calcium sulfate in an indoor temperature-controlled, recirculating culture system without any natural productivity. Experimental diets were formulated to contain 0 (basal), 0.4, 1.2, 1.6, or 2.0% acidic calcium sulfate (ACS) by weight. Shrimp fed in excess, 15 times a day using automatic feeders. Weight gain and survival among treatments were excellent, but not significantly different ( P > 0.05). Denaturing gradient gel electrophoresis analysis revealed that the enteric microbial community of shrimp fed the basal diet differed markedly from those fed the acidifier on the basis of 64.9% similarity coefficient. Shrimp fed the commercial acidifier at 1.2 and 2.0% responded significantly ( P < 0.05) better to reduced stress and displayed enhanced immune responses including hemocyte phagocytic capacity, hemolymph protein concentration, hyaline cell counts, and hemolymph glucose, compared with shrimp fed the basal diet. These results point to an enhanced performance in terms of positive shifts in the composition of enteric microbial communities as well as improved immune performance, with no changes in growth or survival. [ABSTRACT FROM AUTHOR]

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]