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Effects Of Dietary Gamma Aminobutyric Acid And Sodium Butyrate On Growth Performance, Antioxidant Status And Intestinal Structure Of Grass Carp(Ctenopharyngodon Idellus)

Posted on:2017-03-28Degree:MasterType:Thesis
Country:ChinaCandidate:F WuFull Text:PDF
GTID:2283330485477694Subject:Aquaculture
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Gamma aminobutyric acid(GABA) and sodium butyrate(NaB), as feed additives, has a variety of physiological function. The objective of this study was to investigate the effects of GABA and sodium butyrate on growth performance, antioxidant status and intestinal structure of grass carp. Two experiments were done.1. GABA is one of the inhibitory neurotransmitters that may have the ability to regulate the appetite. This study aimed to evaluate the effects of dietary GABA, as a feed additive, on growth performance and antioxidant status of juvenile grass carp. Five basal diets with graded levels of GABA(0, 20, 50, 100, 200 mg/kg) were fed to grass carp juveniles(mean weight: 2.0g) for 8 weeks. The results showed that specific growth ratio(SGR) and weight gain(WG) varied significantly(P > 0.05) with dietary GABA level and showed a first increasing and then decreasing trend, peaked at the group with GABA 50 mg/kg. The survival rate(SR) of juvenile grass carp was not affected by dietary GABA level(P > 0.05). No significant difference was observed on the whole body composition among treatments(P > 0.05). Dietary GABA showed significant(P > 0.05) effect on hepatic glutathione peroxidase(GPx) activity, superoxide dismutase(SOD) activity, total antioxidant capacity(T-AOC) and malondialdehyde(MDA) content. The hepatic GPx activity increased significantly(P < 0.05), peaked at the group with GABA 100 mg/kg, and then showed a decreased trend. And the hepatic SOD activity and T-AOC showed the same trend. Inversely, there was a significant decrease of the hepatic MDA content with the supplementation of GABA(P < 0.05), and then showed an increased trend. And the lowest MDA content was observed in the group of 100 mg/kg. No significant differences were observed in the gene expression of neuropeptide(NPY), cholecystokinin(CCK), Leptin and Ghrelin in the liver among groups. However, the NPY and Ghrelin mRNA expression levels in the brain were increased significantly with the GABA level, peaked at the groups of 50 mg/kg, and then showed a decreased trend. The results of this study indicated that the diet supplemented with a certain amount of GABA could promote growth of juvenile grass carp, improve antioxidant capacity. However, dietary excess GABA would have no effects on the growth and antioxidant capacity. Based on the quadratic regression analysis of SGR, the optimum supplementation of dietary GABA in juvenile grass carp is suggested to be 87.5 mg/kg diet.2. A 49 d feeding trial was conducted to study the effects of sodium butyrate on growth performance, antioxidant status and gut development of juvenile grass carp. Five isoenergetic and isonitrogenous experimental diets were compounded by the supplementation in the basal diet with gradient sodium butyrate at 0, 500, 1000, 2000, 3000 mg/kg, respectively. A total of 375 juvenile grass carp(about 3.4g) were randomly allocated into 5 diet treatments, each treatment has three replicates. The result showed that the specific growth rate(SGR) of Na B1000 and NaB2000 group was significantly higher(P < 0.05) than those of the other experiment groups. Moreover, the lowest specific growth rate(SGR) was observed in NaB3000 group. Feeding rate and the whole body proximate composition including moisture, crude lipid, crude protein and crude ash were not affected by sodium butyrate(P > 0.05). As for the T-SOD in hepatopancreas, the activities in the experiment groups were significantly higher than that in the control group(P < 0.05). GSH activity in hepatopancreas were significantly up-regulated by dietary sodium butyrate level(P < 0.05), GSH activity at NaB1000, NaB2000, NaB3000 groups was significantly higher than 0, 500 mg/kg groups.The expression levels of mRNA encoding PepT-1 and LAT2 in the foregut both showed an increasing first and then decreasing tendency as the dietary sodium butyrate level increased(P < 0.05), and peaked in NaB1000 group and in NaB1000 and Na B2000 groups, respectively. Based on the results of SGR, the optimum supplementation of dietary NaB in juvenile grass carp is suggested to be 2000 mg/kg diet.
Keywords/Search Tags:GABA, sodium butyrate, grass carp, growth, antioxidant status, intestinal structure
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