We evaluated the effects of supplemental coated and crystalline methionine （Met） on the growth performance and feed utilization of juvenile cobia （Rachycentron canadum Linnaeus） in a 60-d feeding trial. Fish group...We evaluated the effects of supplemental coated and crystalline methionine （Met） on the growth performance and feed utilization of juvenile cobia （Rachycentron canadum Linnaeus） in a 60-d feeding trial. Fish groups were fed one of six isonitrogenous and isolipidic diets： 1） fishmeal control; 2） un- supplemented experimental （low-fish-meal diet deficient in Met）; or 3） one of four Met diets supplemented with crystalline L-Met, cellulose-acetate-phthalate coated L-Met, acrylic-resin coated L-Met, or tripalmitin- polyvinyl alcohol coated L-Met. The test diets were fed to triplicate groups of cobia （initial body weight 5.40-4-0.07 g） twice a day. The weight gain and specific growth rate of the fish fed the RES diet were highest among the Met-supplemented groups and were 23.64% and 7.99%, respectively, higher than those of the fish fed with the un-supplemented experimental diet （P〈0.05）. The protein efficiency ratio of the fish fed the MET diet was significantly higher than that of the fish fed the un-supplemented experimental diet and the fish in the other methionine supplementation groups （P〈0.05）. Our results suggest that supplementation of crystalline Met in low-fish-meal diets promotes the growth performance of juvenile cobia.展开更多
This experiment was conducted to investigate the effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia(Rachycentron canadum).Six iso nitrogenous diets were prepared to ...This experiment was conducted to investigate the effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia(Rachycentron canadum).Six iso nitrogenous diets were prepared to vary in lipid-to-carbohydrate ratio(g/g)as follows:Dl,2.26;D2,1.31;D3,0.78;D4,0.47;D5,0.34;and D6,0.23.Cobias were fed to satiety for 8 weeks.The weight gain and protein efficiency ratio in Dl group were significantly lower than those in other groups(P<0.05),accompanied by a lower level of feed conversion ratio(P<0.05).Protein retention efficiency in D4 and D6 and whole body protein in D4 and D5 were significantly higher than those in D1 group(P<0.05).Survival rate in D4 group was the highest among all groups and was significantly higher than that in Dl,D2 and D5(P<0.05).In terms of serum triglyceride,D1 and D2 were significantly higher than D6(P<0.05).Hepatosomatic index in D3 and D4 was significantly lower than that in D1(P<0.05).Fructose-1,6-diphosphatase in D4 was significantly higher than that in D1 and D3(P<0.05).Phosphofructokinase in D3 and D4 and malic enzyme in D4 and D5 were significantly higher than those in other groups(P<0.05).Results indicate that cobia utilizes carbohydrates as energy source more efficiently than it utilizes lipids.The optimal lipid-to-carbohydrate ratio in juvenile cobia diets is 0.47.展开更多
基金Supported by the Special Fund for Agro-Scientific Research in the Public Interest(No.201003020)the Pearl River Scholar Funded Scheme for Universities and Colleges in Guangdong Province(GDUPS,No.2011)the Natural Science Foundation of Guangdong Ocean University of China(No.1212345)
文摘We evaluated the effects of supplemental coated and crystalline methionine （Met） on the growth performance and feed utilization of juvenile cobia （Rachycentron canadum Linnaeus） in a 60-d feeding trial. Fish groups were fed one of six isonitrogenous and isolipidic diets： 1） fishmeal control; 2） un- supplemented experimental （low-fish-meal diet deficient in Met）; or 3） one of four Met diets supplemented with crystalline L-Met, cellulose-acetate-phthalate coated L-Met, acrylic-resin coated L-Met, or tripalmitin- polyvinyl alcohol coated L-Met. The test diets were fed to triplicate groups of cobia （initial body weight 5.40-4-0.07 g） twice a day. The weight gain and specific growth rate of the fish fed the RES diet were highest among the Met-supplemented groups and were 23.64% and 7.99%, respectively, higher than those of the fish fed with the un-supplemented experimental diet （P〈0.05）. The protein efficiency ratio of the fish fed the MET diet was significantly higher than that of the fish fed the un-supplemented experimental diet and the fish in the other methionine supplementation groups （P〈0.05）. Our results suggest that supplementation of crystalline Met in low-fish-meal diets promotes the growth performance of juvenile cobia.
基金supported by the modern agricultural technology extension system construction project of Guangdong Province(2018LM0822018LM083+1 种基金2019KJ115)the team building project of Guangdong academy of agricultural Sciences(201614TD).
文摘This experiment was conducted to investigate the effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia(Rachycentron canadum).Six iso nitrogenous diets were prepared to vary in lipid-to-carbohydrate ratio(g/g)as follows:Dl,2.26;D2,1.31;D3,0.78;D4,0.47;D5,0.34;and D6,0.23.Cobias were fed to satiety for 8 weeks.The weight gain and protein efficiency ratio in Dl group were significantly lower than those in other groups(P<0.05),accompanied by a lower level of feed conversion ratio(P<0.05).Protein retention efficiency in D4 and D6 and whole body protein in D4 and D5 were significantly higher than those in D1 group(P<0.05).Survival rate in D4 group was the highest among all groups and was significantly higher than that in Dl,D2 and D5(P<0.05).In terms of serum triglyceride,D1 and D2 were significantly higher than D6(P<0.05).Hepatosomatic index in D3 and D4 was significantly lower than that in D1(P<0.05).Fructose-1,6-diphosphatase in D4 was significantly higher than that in D1 and D3(P<0.05).Phosphofructokinase in D3 and D4 and malic enzyme in D4 and D5 were significantly higher than those in other groups(P<0.05).Results indicate that cobia utilizes carbohydrates as energy source more efficiently than it utilizes lipids.The optimal lipid-to-carbohydrate ratio in juvenile cobia diets is 0.47.
