Effects of supplementing coated methionine in a high plant-protein diet on growth, antioxidant capacity, digestive enzymes activity and expression of TOR signaling pathway associated genes in gibel carp, Carassius auratus gibelio.

This study explored the impacts of supplementation of different levels of coated methionine (Met) in a high-plant protein diet on growth, blood biochemistry, antioxidant capacity, digestive enzymes activity and expression of genes related to TOR signaling pathway in gibel carp (Carassius auratus gibeilo). A high-plant protein diet was formulated and used as a basal diet and supplemented with five different levels of coated Met at 0.15, 0.30, 0.45, 0.60 and 0.75%, corresponding to final analyzed Met levels of 0.34, 0.49, 0.64, 0.76, 0.92 and 1.06%. Three replicate groups of fish (initial mean weight, 11.37 ± 0.02 g) (20 fish per replicate) were fed the test diets over a 10-week feeding period. The results indicated that with the increase of coated Met level, the final weight, weight gain (WG) and specific growth rate initially boosted and then suppressed, peaking at 0.76% Met level (P< 0.05). Increasing dietary Met level led to significantly increased muscle crude protein content (P< 0.05) and reduced serum alanine aminotransferase activity (P< 0.05). Using appropriate dietary Met level led to reduced malondialdehyde concentration in hepatopancreas (P< 0.05), improved superoxide dismutase activity (P< 0.05), and enhanced intestinal amylase and protease activities (P< 0.05). The expression levels of genes associated with muscle protein synthesis such as insulin-like growth factor-1, protein kinase B, target of rapamycin and eukaryotic initiation factor 4E binding protein-1 mRNA were significantly regulated, peaking at Met level of 0.76% (P< 0.05). In conclusion, supplementing optimal level of coated Met improved on fish growth, antioxidant capacity, and the expression of TOR pathway related genes in muscle. The optimal dietary Met level was determined to be 0.71% of the diet based on quadratic regression analysis of WG.

Alpha-ketoglutaric acid mitigates the detrimental effects of soy antigenic protein on the intestinal health and growth performance of Mirror carp Cyprinus carpio.

The study investigated the alleviated effects of Alpha-ketoglutaric acid (AKG) on the intestinal health of mirror carp (Cyprinus carpio Songpu) caused by soy antigenic protein. The diets were formulated from fishmeal (CON), 50% soybean meal (SBM), the mixture of glycinin and ß-conglycinin (11 + 7S) and adding 1% AKG in the 11 + 7S (AKG). Carp (~ 4 g) in triplicate (30 fish per tank) was fed to apparent satiation thrice a day for six weeks. Compared with CON, SBM treatment resulted in significantly poor growth performance (P < 0.05), whereas 11 + 7S and AKG treatments were not significantly different from CON (P > 0.05). Gene expression of tumor necrosis factor (TNF-α) and interleukin-1 ß (IL-1ß) in proximal intestines (PI) and distal intestines (DI) were increased (P < 0.05), and transforming growth factor (TGF-ß) in PI and middle intestines (MI) was decreased (P < 0.05) in both SBM and 11 + 7S. The caspase-3 in DI increased in SBM (P < 0.05) and the caspase-3 and caspase-9 in DI increased in 11 + 7S (P < 0.05); conversely, TGF-ß in PI and MI was increased, TNF-α and IL-1ß in the MI, caspase-3, and caspase-9 in DI was decreased in AKG (P < 0.05). The TOR (target of rapamycin) in PI and MI, ACC in PI, MI and DI was decreased in SBM (P < 0.05), the AMPK in the PI and DI, TOR in PI, MI and DI, ACC in PI and DI, 4E-BP in DI was reduced in 11 + 7S (P < 0.05). AMPK in the PI and DI, ACC in the PI and MI, TOR in PI, MI, and DI, 4E-BP in PI and DI was recovered by AKG supplementation (P < 0.05). Lipids and lipid-like metabolism, organic acids and derivatives metabolism increased in AKG dietary treatment. In conclusion, AKG reduces the expression of intestinal inflammation and apoptosis pathway and changes glycerophospholipid metabolism and sphingolipid metabolism in the intestine of fish.

Efficacy of purified nucleotide supplements on the growth performance and immunity of hybrid striped bass Morone chrysops x Morone saxatilis.

Fishmeal is being increasingly replaced in aquatic animal diets with alternative plant protein feedstuffs such as soybean meal which have lower concentrations of nucleotides; therefore, supplemental sources of exogenous nucleotides in diets could become increasingly important. A 9-week feeding trial was conducted with triplicate groups of juvenile hybrid striped bass (average initial body weight ± standard deviation, 5.6 ± 0.1 g) to determine the effects of supplementing single purified nucleotides on the growth performance and immune parameters. The basal diet, which utilized menhaden fishmeal (25%) and soybean meal (75%) as protein sources, contained 44% protein, 10% lipid and an estimated digestible energy level of 3.5 kcal g-1. Single additions of 5'- adenosine monophosphate (AMP), 5'- uridine monophosphate (UMP), 5'- cytidine monophosphate (CMP), 5'- guanosine monophosphate (GMP), and 5'- inosine monophosphate (IMP) disodium salts (Chem-Impex International, Wood Dale, Illinois, USA) were evaluated with each nucleotide added to the basal diet at 0.5% of dry weight at the expense of cellulose. A positive control diet in this trial was a diet containing 5'- AMP from Sigma-Aldrich also supplemented at 0.5% by weight. Results showed significantly (P < 0.05) improved weight gain between fish fed AMP-supplemented diets and the basal diet. No statistical significance (P > 0.05) was detected in whole-body proximate composition and protein retention of fish fed any of the dietary treatments. The respiratory burst of whole blood phagocytes also was significantly (P < 0.05) higher in fish fed the AMP Sigma diet compared to the other dietary treatments. Dietary IMP and AMP both significantly (P < 0.05) enhanced the capacity of isolated phagocytes to generate extracellular superoxide anion compared to all other dietary treatments. No significant differences were seen in other innate immune parameters such as plasma lysozyme, total plasma protein, and total immunoglobulin. The ability of isolated B lymphocytes to proliferate prompted by the presence of lipopolysaccharides was significantly (P < 0.05) different among dietary treatments with the highest simulation index observed in fish fed the diets containing AMP Sigma and UMP; however, it was not significantly different from that of fish fed the basal diet. Based on all the measured responses, it is concluded that AMP at 0.5% of diet had the most positive influence on growth performance and innate immunostimulation of hybrid striped bass.