The dietary requirement of vitamin B 6 (pyridoxine) of Pacific white shrimp, Litopenaeus vannamei, at 3‰ salinity was evaluated by examining the growth responses, survival, and amino transferase activities. The basal diet was formulated using vitamin-free casein as the protein source. Six levels (0, 35, 70, 105, 140, and 200 mg/kg diet) of vitamin B 6 were added to the basal diet, yielding the final vitamin B 6 contents of 2.17, 32.43, 65.79, 96.97, 137.13, and 189.56 mg/kg, respectively. Each diet was fed to the triplicate groups of shrimp for 30 d. Percent body weight gain and condition factor of shrimp significantly increased with the increasing levels of dietary vitamin B 6 up to 137.13 mg/kg diet. Exceeding this level, however, did not further improve the weight gain. The survival rate also increased at each incremental increase of dietary vitamin B 6 , but no significant increase was observed beyond 65.69 mg/kg. Both glutamic oxalacetic transferase (GOT) and glutamic pyruvic transferase (GPT) activities increased with increasing levels of dietary vitamin B 6 and the maximum value reached at 96.97 mg vitamin B 6 /kg. No significant differences were observed in both GOT and GPT activities of the shrimp-fed diets containing 96.97, 137.13, and 189.56 mg vitamin B 6 /kg. Broken-line regression analysis using weight gain, specific growth rate, and amino transferase activities indicates that the optimal dietary vitamin B 6 requirement is 106.95-151.92 mg/kg at 3‰ salinity.

The use of meat and bone meal (MBM) was evaluated as a replacement for ¢sh meal in a practical diet formulated to contain 41% protein and 8% lipid. Anchovy meal was replaced by 0%, 20%, 30%, 40%, 50%, 60% and 80% of MBM (diets 1^7) respectively. Healthy post larvae of Litopenaeus vannamei were reared in an indoor, semi-closed recirculating system. Each dietary treatment was fed to triplicate groups of 40 shrimp per tank (260 L) arranged in a completely randomized design. The shrimp were hand-fed to near-satiation three times daily between 07:00 and 18:00 hours for 56 days. There were no sig-ni¢cant di¡erences (P40.05) in growth performance among shrimp fed diets1^6. However, shrimp fed diet 7 had signi¢cantly lower (Po0.05) growth than those fed diet 2 or diet 4. Survival ranged from 95% to 100% and did not signi¢cantly (P40.05) di¡er. Feed conversion ratio (FCR) and carcass composition of the shrimp were not signi¢cantly (P40.05) affected by dietary treatments. No signi¢cant di¡erences (P40.05) in protein e⁄ciency ratio (PER) were found among shrimp fed diets 1-6. However, shrimp fed diet 7 had signi¢cantly lower (Po0.05) PER than those fed diet 1 or diet 4. Results showed that up to 60% of ¢sh meal protein can be replaced by MBM with no adverse e¡ects on growth, survival, FCR, PER and body composition of L. vannamei.

A study was conducted to investigate the effect of dietary yeast polysaccharides on some hematologic parameters and intestinal morphology of channel catfish. Channel catfish were fed diets containing yeast polysaccharides at 0 (control), 0.1, 0.2, or 0.3 % for 7 weeks. Each diet was provided to 10 channel catfish specimens (5.82 ± 0.13 g initial weight) replicated 3 times in individual 250 L fiberglass tanks. Some hematologic parameters, leukocyte phagocytic activity, and intestinal morphology were monitored. After 7 weeks of trial, 0.2 % yeast polysaccharides resulted in significantly higher (P < 0.05) monocyte numbers. Furthermore, fish fed 0.2 % yeast polysaccharide diet had higher (P < 0.05) phagocytic rate of leukocyte. And 0.3 % yeast polysaccharide enhanced (P < 0.05) phagocytic index of leukocyte. Histological evaluation showed yeast polysaccharide supplementation increased the height of intestine fold (0.1, 0.2 and 0.3 %) and the thick of muscular layers (0.2 %) in intestine (P < 0.05). In addition, 0.1 and 0.3 % yeast polysaccharide supplementation improved the number of goblet cells (P < 0.05). The results of this trial indicate that yeast polysaccharides supplementation could affect blood monocytes, improve leukocytes phagocytic activity, and the development of intestine in channel catfish.

Background Coexpression network analysis is a powerful tool to reveal transcriptional regulatory mechanisms, identify transcription factors, and discover gene functions. It can also be used to investigate changes in coexpression patterns in response to environmental insults or changes in experimental conditions. Maternal nutrition is considered a major intrauterine regulator of fetal developmental programming. The objective of this study was to investigate structural changes in gene coexpression networks in the muscle of bull beef calves gestated under diets with or without methionine supplementation. Both muscle transcriptome and methylome were evaluated using next generation sequencing. Results Maternal methionine supplementation significantly perturbed coexpression patterns in the offspring’s muscle. Indeed, we found that neither the connection strength nor the connectivity pattern of six modules (subnetworks) detected in the control diet were preserved in the methionine-rich diet. Functional characterization revealed that some of the unpreserved modules are implicated in myogenesis, adipogenesis, fibrogenesis, canonical Wnt/β-catenin pathway, ribosome structure, rRNA binding and processing, mitochondrial activities, ATP synthesis and NAD(P) H oxidoreductases, among other functions. The bisulfite sequencing analysis showed that nearly 2% of all evaluated cytosines were differentially methylated between maternal diets. Interestingly, there were significant differences in the levels of gene body DNA methylation between preserved and unpreserved modules. Conclusions Overall, our findings provide evidence that maternal nutrition can significantly alter gene coexpression patterns in the offspring, and some of these perturbations are mediated by changes in DNA methylation.

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