Studies on dietary lysine requirement of Macrobrachium nipponense

Abstract:

7 purified diets with various lysine levels ranging from 0.85% to 2.95% were formulated by using crystal amino acids and intact protein amino acids from 10% casein and 5% gelatin. Levels of crystal lysine were graded and the percentage differences were compensated by levels of mixture of aspartic acid and glutamate (1∶〖KG-*2〗1) accordingly. Levels of other amino acids were maintained to analyzed ones in 40% protein of tail muscle. The diets were fed to 7 triple groups of Macrobrachium nipponense juveniles initially weighing 0.13 g for 7 weeks. The survival rates had no significantly differences (P>0.05) between treatments, while the weight gains of shrimps fed diets with various levels of lysine were significantly affected (P<0.05). Weight gain increased with increasing dietary lysine levels from 0.85% to 1.90%, and further increase dietary lysine level seemed to reach a platform. Feed efficiencies of shrimp fed diets with lysine levels ranging from 1.55% to 2.60% were significantly higher than that of shrimp fed a diet with 0.85% lysine (P<0.05). Broken line model regressions analysis of weight gain data showed that the dietary lysine requirement of the shrimp was 1.91% of dry diet or 5.41% of dietary protein. And based on this result, the recommended requirements for other 9 essential amino acids were calculated by using a reported essential amino acids profile through analyzing the tail muscle.