Partial replacement of fish meal by soybean meal with or without methionine and phytase supplement in diets for juvenile Chinese sucker, Myxocyprinus asiaticus

摘要

This study was designed to evaluate the effects of using soybean meal supplemented with or without methionine (M) and graded levels of phytase (P) to replace high-level (60%) fish meal in the diets for juvenile Chinese sucker. Seven experimental diets (about 430 g kg(-1) crude protein on dry matter basis) were formulated from practical ingredients. The control diet (FM) was formulated to contain 400 g kg(-1) white fish meal (FM), whereas in the other six diets (diets 2-7), soybean meal (SBM) was used to replace 60% fish meal with or without methionine (3 g kg(-1)) and 0,500, 1000, 1500 and 2000 U kg(-1) phytase (designated as SBM, SM, SMP500, SMP1000, SMP1500 and SMP2000, respectively). Results from the feeding trial indicated that SBM without any methionine or phytase supplement replacing about 60% FM significantly affected the growth of fish (P 0.05). Weight gain of fish fed diet SM was significantly higher than the fish fed diet SBM, but still much lower than fish fed the control diet (P 0.05). SBM with methionine and phytase supplement significantly improved the growth of fish and apparent digestibility coefficients of phosphorus compared with the groups which fed diet SBM and diet SM (P 0.05). Weight gain of fish fed SMP1000, SMP1500 and SMP2000 had no significant difference than fish fed control diet. Furthermore, fish fed SMP1500 showed optimum weight gain and ADC of phosphorus between these three groups. This suggested that soybean meal with 3 g kg(-1) methionine and 1500 U kg(-1) phytase supplement could successfully replace 60% fish meal in the diet for juvenile Chinese sucker without affecting growth and enhanced the apparent digestibility coefficient of phosphorus.