Effects of dietary protein content on growth performance and digestive emzyme activities of F_2 generation Penaeus monodon

Effects of seven dietary protein contents(34%, 36%, 38%, 40%, 42%, 44%, 46%) on growth performance and digestive emzyme activities of domestic F2generation Penaeus monodon were studied under laboratory condition. P.monodon(2.84±0.04 g) were fed with the seven diets in triplicate for 48 d. The results showed that shrimp fed with 38%dietary protein achieved the highest weight growth rate(WG) and special growth rate(SGR) and the lowest FCR. P.monodon fed with 34% dietary protein achieved the highest protein efficiency ratiol(PER), without statistical differences with that fed with 36%, 38% dietary protein, significantly higher than shrimp fed with 40% and above dietary protein.Survival rate of low-protein group(34%~42%) was significantly higher than that of high-protein group(44%, 46%). Dietary protein content also affected the whole body composition of P. monodon. Body crude protein content increased, while body crude fat content decreased with dietary protein level increasing, but there was no statistical difference of muscle crude protein in each group. Pepsin of shrimp fed with 34% dietary protein was the highest, with the increase of protein content, it increased first, then decreased, and then increased again, showed fluctuation and complementary trend with liver protease content.Amylase in stomach was higher than that in hepatopancreas, but without statistical differences with stomach amylase in each group. Lipase in stomach and hepatopancreas showed a downward trend with protein content increasing. The growth performance and digestive enzyme activities indicated that the effect of feed with low protein level on domesticated F2generation P. monodon growth was favorable, suggesting that dietary protein of 38%was more appropriate.