The Application Of Soy Protein Concentrate,Methionine,and Hydroxyl Methionine Calcium In White Shrimp Feed

The present study was conducted to evaluate the effects of partially replacing dietary fish meal with soy protein concentrate in diet containing 20% fish meal,and compare the supplemental effects of crystalline methionine and methionine hydroxy analogue calcium in diet containing 15% fish meal on growth,nutrient digestibility,nutrient retention ratio and hemolymph biochemical indices of white shrimp(Litopenaeus vannamei).The results would provide theoretical foundation to reduce the inclusion level of fish meal and to properly use amino acid in white shrimp feed.Exp.1 Substitute of soy protein concentrate for fish meal in diets of white shrimpThe present study was conducted to evaluate the effects of partially replacing dietary fish meal(FM)with soy protein concentrate(SPC)on growth,body composition,digestive enzyme activities and nutrient digestibility of white shrimp.Five isonitrogenous diets with SPC inclusion levels of 0.0%,2.5%,5.0%,7.5% and 10.0%,were prepared to replace 0.0%,12.5%,25.0%,37.5%,50.0% FM in basal diet containing 20.0% FM,respectively,and fed to white shrimp with an initial body weight of 1.80 g.After 49 days feeding,the weight gain in all group were 499.2%,478.3%,471.1%,412.2 and 415.8%,feed conversion ratio were 1.51,1.63,1.62,1.74 and 1.77.5.0% SPC diet did not affect the growth of white shrimp(P>0.05),but weight gain was decreased by 17.43% or 16.67%(P<0.05)and the apparent digestibilities of dry matter were decreased by 3.88% or 4.43% and the apparent digestibilities of protein were decreased by 4.14% or 4.31%,hepatopancreas protease activity were decreased by 10.46% or 14.62%(P<0.05)by the inclusion of 7.5% or 10.0% SPC.With the increase of dietary SPC level,the whole body crude protein content decreased from 19.09% to 18.69%,serum triglycerides decreased from and 0.63 mmol/L to 0.50 mmol/L,cholesterol contents decreased from 1.62 mmol/L to 1.23 mmol/L(P<0.05),while the whole body lipid content increased from 1.99% to 2.10%(P<0.05).Muscle amino acids showed no significant differences(P > 0.05)among treatments except glycine(Gly).The above results indicated that 25% FM could be substituted by SPC and the SPC inclusion level was 5% without negative effects on the growth of white shrimp.Exp.2 Comparative study on the utilization of crystalline methionine and methionine hydroxy analogue calcium by white shrimpThe present study was conducted to compare the supplemental effects of crystalline methionine and methionine hydroxy analogue calcium(MHA-Ca)on the performance of white shrimp.Eight diets with isonitrogen and isoenergy were formulated as positive diets(containing 20% fish meal),negative control diet(containing 15% fish meal)without or with the addition of 0.02%,0.04% and 0.07% DL-methionine(DL-Met)and 0.03%,0.05% and 0.08% MHA-Ca.The diet containing 0.04% DL-Met had the same Met level as positive control diet.The eight diets were fed to white shrimp with an initial body weight of 0.9 g for 49 days.After the feeding trial,the serum total protein(TP),total free amino acids(TFAA),and activities of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)were measured at the 0,1,2,3,4,5h after feeding.The weight gain rate(WGR)of the eight groups were 1632.1%,1492.3%,1529.6%,1530.2%,1547.1%,1570.1%,1564.3%,1611.5%,and feed conversion ratio(FCR)were 1.30,1.50,1.40,1.47,1.37,1.37,1.39,1.33,respectively.Dietary DL-Met did not significantly affect the WGR and FCR(P<0.05).but the supplementation of 0.08% MHA-Ca increased WGR by 7.98% and increased retention ratios of protein and lipid,and reduced FCR by 11.33%(P<0.05),when compared the negative control,and reached the similar levels as positive control.In the serum TP level,all groups peaked at the 2nd h after feeding.The serum TFAA of MHA-Ca groups,positive and negative controls peaked at the 3rd h,but the peaking time of DL-Met groups were advanced to the 2nd h after feeding.In the serum activities of AST and ALT,all MHA-Ca groups peaked at the 2nd h,but DL-Met groups peaked at the 1st h after feeding.The above results indicated that the supplementation of 0.08% MHA-Ca in low fish meal diet(containing 15% fish meal)could improve the growth,but dietary DL-Met had no significant effects on growth performance of white shrimp.