Effects Of Dietary α-ketoglutarate Supplementation On Growth Performance, Antioxidant Capacity, Digestive Enzyme Activity And Gene Expression Of Hybrid Sturgeon(acipenser Schrenckii♀× A. Baeri♂)

The aim of this experiment to study the effects of α-ketoglutarate-add diet on growth performance and the intestinal and liver development of hybrid sturgeon under two kinds of protein sources(SPC and SPC+FM) with or without 1% AKG. The experimental fish was purchased from Fangshan aquaculture base in Beijing and was disinfected by saline water(salt concentration 5%) and then placed in the workshop with controlled water circulation system. The period of acclimatization is two weeks. A total of 500 hybird sturgeon with an average initial body weight of(7.65±0.04) g were divided into 4 groups, at random with 5 replicates per group and 25 fish per replicate. The water of this experiment was: the temperature was about 22℃, dissolved oxygen greater than 5 mg/L with natural light. During this experiment, the fish was fed three times a day, at 08:00, 13:00, 17:00 and the residual feeds and feces were cleaned every day. The quality of water was tested at certain time. The water was changed once every 7 days, every time volume changed of 1/3~1/2 to ensure good water quality. The experiment was lated for 8 weeks.The results showed as follows:(1) The impact on the growth performance of hybrid sturgeon : AKG significantly increased the WGR,and PER(P<0.05);decreased the FCR; had no significant effects on the CF and VSI(P>0.05). Two kinds of protein source had no significant effects on the growth performance of hybrid sturgeon(P>0.05). The protein source and the concentration of AKG interaction significantly effects on the WGR, PER, FCR.(P<0.05); had no significant effects on the CF and VSI(P>0.05). AKG had no significant effects on the body composition(P>0.05); two kinds of protein source had no significant effects on the body composition(P>0.05); the protein source and the concentration of AKG had no significant effects on the body composition(P>0.05).AKG significantly increased the concentration of Arg(P<0.05), had no significant effects on other essential aminoacid concentration(P>0.05); SPC+FM source significantly increased the concentration of Met, Lys and Leu(P<0.05); the protein source and the concentration of AKG had no significant effects on the concentration of essential aminoacid(P>0.05). AKG significantly increased the concentration of Asp and Glu(P<0.05); had no significant effects on other essential non-amino-acid concentration(P>0.05); SPC+FM source significantly increased the concentration of Tyr(P<0.05); the protein source and the concentration of AKG had significant effects on the concentration of Pro(P<0.05), had no significant effects on other essential non-aminoacid concentration(P>0.05). AKG significant declined blood ammonia(P<0.05); SPC+FM source significantly declined the blood ammonia and increased the ALP activity(P<0.05); the protein source and the concentration of AKG had no significant effects on blood ammonia and ALP activity(P>0.05).(2) The impact on the intestinal of hybrid sturgeon :AKG significantly increased theintestinal Gln content and GS activity in intestine(P<0.05), had no significant effects on intestinal ALP activity(P>0.05); SPC+FM source significantly increased the intestinal ALP activity(P<0.05); the protein source and the concentration of AKG had no significant effects in intestine(P<0.05).Gln content, GS activity and ALP activity(P>0.05). AKG significantly increased the villus height of hindgut(P < 0.05), two kinds of protein sources had no significant effects on the morphology in intestine(P > 0.05), the protein source and the concentration of AKG had no significant effects on the morphology in intestine(P > 0.05). AKG significantly increased the protease activity(P < 0.05), and had no significant effects on lipase and amylase activity(P > 0.05), SPC source significantly increased the protease activity and amylase activity(P < 0.05), SPC+FM source had no significant effects on intestinal digestive enzyme activity in intestine(P > 0.05), the protein Source and the concentration of AKG had a significant influence on lipase and amylase activity(P < 0.05). AKG significantly increased the content of SOD activity(P < 0.05), and significantly decreased the content of MDA in intestine(P < 0.05), AKG had no significant effects on content of GSH and CAT in intestine(P >0.05), two kinds of protein sources had no significant effects on intestinal antioxidant capacity(P > 0.05), the protein source and the concentration of AKG had a significant influence on the content of MDA in intestine(P < 0.05), and had nosignificant effects on other antioxidant indices(P> 0.05).(3) The impact on the liver of hybrid sturgeon :AKG significantly decreased the content of MDA activity, increased the content of GSH activity(P < 0.05); SPC significantly increased the content of GSH activity(P < 0.05), two kinds of protein sources had no significant effects on antioxidant capacity(P > 0.05); the protein source and the concentration of AKG had no significant effects on other antioxidant indices(P> 0.05). AKG significantly increased the liver Gln content and GS activity(P<0.05), had no significant effects on ALP activity(P>0.05); two kinds of protein sources had no significant effects on Gln content,GS activity and ALP activity(P>0.05); the protein source and the concentration of AKG had no significant effects on Gln content,GS activity and ALP activity(P>0.05). AKG significantly increased the IGF-I and GH expression(P<0.05); two kinds of protein sources had no significant effects on the IGF-I and GH expression(P>0.05); the protein source and the concentration of AKG had no significant effects on the IGF-I and GH expression(P>0.05).The conclusions were drawn as following:1 The addition of AKG could improve the growth performance, Gln synthesis, promote intestinal development, increase intestinal digegtive enzyme activity and antioxidant capacity, and promote liver antioxidant capacity and liver-growth-related gene expression of juvenile hybrid sturgeon. All of these illustrates that AKG could be added to feedingsuff as the replacement of Gln, and could improve the growth performance of juvenile hybrid sturgeon.2 SPC could save the use of fish meal, when added to the feedingstuff at a certain ratio.