Effects of dietary α-ketoglutarate supplementation on the growth performance, glutamine synthesis and amino acid concentrations of juvenile hybrid sturgeon Acipenser schrenckii ♀ x Acipenser baerii ♂ fed high levels of soy protein concentrate

The present study was conducted to determine the effects of dietary alpha-ketoglutarate (AKG) supplementation on the growth performance, glutamine synthesis and amino acid concentrations of juvenile hybrid sturgeon Acipenser schrenckii female x Acipenser baerii male fed high levels of soy protein concentrate (SPC). The study consisted of four isoproteic and isolipidic diets (including 100 g of fish meal (FM)/kg or 0 FM) with or without 10 g AKG/kg supplementation. The results showed that the SPC diet had no effect (P>0.05) on the weight gain rate (WGR), feed conversion ratio (FCR), protein efficiency ratio (PER), condition factor (CF) or viscerosomatic index (VSI) compared with the FM diet. The WGR and PER were increased (P<0.05) by the addition of AKG compared with the FM and SPC diets. However, the FCR was decreased (P<0.05) by the addition of AKG. The concentration of ammonia in serum was decreased (P<0.05) by the addition of AKG compared with the FM and SPC diets. The Gln and activity of GS in the intestine of sturgeon fed the SPC + A and FM + A diets were significantly higher (P<0.05) than in sturgeon fed the SPC and FM diets. The concentrations of methionine, leucine and lysine in the muscle of sturgeon fed the SPC diet were significantly lower (P<0.05) than those of muscles in sturgeon fed the FM diet. The concentration of arginine was increased (P<0.05) by the SPC diet or the addition of AKG. The concentrations of aspartate and glutamate were increased (P<0.05) by the addition of AKG compared with the FM and SPC diets. These findings indicate that the SPC diet had no negative effect on growth performance compared with the FM diet (100 g FM/kg), and that dietary AKG supplementation improved the growth performance and glutamine synthesis of the juvenile hybrid sturgeon. (C) 2015 Elsevier B.V. All rights reserved.