INFLUENCE OF DIETARY CARBOHYDRATE LEVELS ON GROWTH AND SOME PHYSIOLOGICAL-BIOCHEMICAL INDEX IN JUVENILE LITOPENAEUS VANNAMEI

The effects of different dietary carbohydrate levels on growth and some physiological-biochemical index in juvenile Litopenaeus vannamei(initial average weight 0.17±0.00g,mean±S.E) were evaluated by using practical diets.The fishmeal and defatted soybean meal were used as main protein source,fish oil and lecithin as main lipid source and wheat meal as the carbohydrate source.Five iso-lipidic(7.5% crude lipid) practical test diets were formulated containing five carbohydrate levels:13.82%,19.41%,25.72%,31.80% and 38.2%,protein levels were 45.86%,42.01%,37.82%,33.30%,29.01%,respectively.Each diet was randomly fed to triplicate groups of 40 shrimps per tank(260 L) for 8 weeks.The water temperature was 28.5±2℃ and the salinity was 28±1‰ during the experimental period.The results showed that the survival and growth was significantly affected by dietary carbohydrate levels(pp>0.05).No significant differences on amylase and a-glucosidase activity of intestine and muscle glycogen were found among dietary treatments(p>0.05).However,protein concentration in intestine was significantly affected by dietary carbohydrate levels(pp>0.05).Glucose and protein concentration in hemolymph were significantly affected by dietary carbohydrate levels(pLitopenaeus vannamei,and the increase of dietary carbohydrate level had some efficient protein-sparing effects.