Effects Of Dietary Protease And Phytase On Growth And Nutrient Utilization Of Crucian Carp,Jian Carp And Tilapia

Exp.1 Effects of dietary phytase on growth,nutrients digestibility and deposition of crucian carpThe present study was conducted to evaluate the effects of supplementation of neutral phytase in diets with various monocalcium phosphate(MCP)levels on the growth,digestibility and deposition of nutrients of Crucian carp(Carassius auratus gibelio)with initial body weight of(39.0±3.0 g).Six diets were preparedas 1.5%,1.0%and 0.5%Ca(H2PO4)2 diets,and phytase supplemented diets(400IU/kg phytatse+1.0% Ca(H2PO4)2 diet,800 IU/kg phytase+1.0% Ca(H2PO4)2diet,400 IU/kg phytase+0.5% Ca(H2PO4)2diet.After10 weeks feeding,the weight gain(WG),digestibilities of dry matter(DM)and phosphorus(P),depositions of protein and ash,whole body P level increased(P<0.05),but serum ALP activity decreased(P<0.05),with the increase of dietary MCP level The WG of fish fed800 IU/kg phytase+1.0% Ca(H2PO4)2 diet was 11.8% higher than the fish fed1.0% Ca(H2PO4)2 diet,and reached the similar level to the group of 1.5%Ca(H2PO4)2.The digestibilities of DM and P,retention ratio of crude protein,ash and P,levels of whole fish P,vertebra Ca and serum TG were also promoted,but serum ALP activity was decreased by the supplementation of 800IU/kg phytase,when compared with the 1.0% Ca(H2PO4)2 group(P<0.05).The supplementation of 400IU/kg phytase in 0.5%,1.0% Ca(H2PO4)2 diet significantly promoted P digestibility and P retention ratio(P<0.05)when compared with 0.5% Ca(H2PO4)2 and 1.0% Ca(H2PO4)2groups,respectively.There were no significant differences in serum levels of TP,ALB,P,Ca among all groups(P>0.05).Results above showed that the supplementation of 800 IU/kg phytase in 1.0% Ca(H2PO4)2 diet could improve the growth and digestibility of dry matter and phosphorus,and 800 IU/kg phytase could substitute the inclusion of 0.5%(5 g/kg)Ca(H2PO4)2.in the diet of crucian carp.Exp.2 Effects of dietary protease and phytase in fish meal free diet with low phosphorus level on growth,nutrients digestibility and deposition of Jian carpTo evaluate the effects of the supplementation of neutral protease and neutral phytase in fish meal free diet with low phosphorus level on the growth,nutrients digestibility,nutrients deposition,serum biochemical index,and intestinal morphology of Jian carp(Cyprinus carpio var.Jian),five diets were prepared as the positive control diet(5% fish meal,1.5% Ca(H2PO4)2,fish meal free diet(FMF)supplemented without or with 175 mg/kg protease,low phosphorus and fish meal free diet(1.0% Ca(H2PO4)2,LP-FMF)supplemented without or with 175 mg/kg protease+300 mg /kg phytase(LP-FMF+Pr+Ph),respectively,for a 10-weeks trial.The results indicated that the control group had the highest weight gain rate(WGR)and the lowest feed conversion ratio(FCR)among all groups(P<0.05).The WGR,the retention ratios of protein and P,the digestibilities of protein and calcium of FMF group and LP-FMF group were significantly lower than those of control group(P<0.05).The supplementation of protease(FMF+protease)improved the WGR by 13.1%(P<0.05),and promoted the digestibilities of protein and calcium,and improved the foregut villus length,and decreased the FCR(P<0.05)compared with FMF group.The LP-FMF+Pr+Ph group showed the higher retention ratios of lipid,protein and phosphorus(P<0.05),the higher digestibilities of protein,phosphorus and calcium(P<0.05),the longer villus length and crypt depth,andthe higher serum phosphorus level(P<0.05)than the LP-FMF group.These results indicated that the supplementation of protease in fish meal free diet and the supplementation of protease and phytase in low phosphorus and fish meal free diet could improve the growth performance,the digestibility and retention ratios of nutrients,and promote the intestinal development of Jian carp.Exp.3 The inclusion of protease and phytase in low P and fish meal free diets improved the growth and nutrients utilization of tilapiaThe study was conducted to evaluate the effects of dietary protease andphytase in fish meal free diet with low phosphorus level on the growth,nutrients digestibility,nutrients deposition,intestinal morphology,and intestinal activities of protease and amylase of tilapiawith initial body weight of(7.7±0.5g).Sevenisonitrogenous diets were prepared as the positive control diet(6% fish meal,1.8% Ca(H2PO4)2,fish meal free diet(FMF),low phosphorus diet(1.2% Ca(H2PO4)2(LP),low phosphorus + fish meal free diet(LP-FMF),and FMF+175 mg/kg protease(FMF+Pr),LP+400 mg/kg phytase(LP+Ph),LP-FMF+175 mg/kg protease+400 mg/kg phytase(LP-FMF+Pr+Ph).After 10 weeks feeding,the control group had the highest weight gain rate(WGR)(1264.4%)and the lowest feed conversion ratio(FCR)(1.16)among all groups(P<0.05).The WGR,the retention ratios of protein,calcium and phosphorus,the digestibilities of DM,protien,phosphorusand calcium of LP,FMFand LP-FMF group were significantly lower than those of the positive control(P<0.05).Compared with LPgroup,the supplementation of phytase(LP+Ph group)improved the WGR by 13.2%(P<0.05),promoted the digestibilities of DM,protien,phosphorus and calcium,improved the foregut villus lengthand the intestinal protease activityat the 2 h after feedin(P<0.05),andshowed the similar growth to the positive control.Compared with FMF group,the supplementation of protease(FMF+Pr grou)pimproved the WGR by 11.1%(P<0.05),promoted the digestibilities of DM,protien and phosphorus,improved the foregut villuslength,the intestinal protease activity at the 0,2h and amylase activity at the0 hafter the feeding(P<0.05)but the WGR of this group was still significantly lower than the positive control(P<0.05),.Compared with LP-FMF group,the supplementation of phytase+protease(LP-FMF+Pr+Ph group)improved the WGR by 13.0%(P<0.05),but the WGR was still significantly lower than the positive control(P<0.05),and this group showed higher retention ratios of ash,protein,phosphorus and calcium(P<0.05),higher digestibilities of DM,protien,phosphorusand calcium(P<0.05),longer villus length and higher intestinal protease activityat 0,2hafter feeding than the LP-FMF group(P<0.05).The above results indicated that the supplementation of protease and phytase in a fish meal free diet with low phosphorus could improve the growth performance,the digestibilities and retention ratios of nutrients,and promote the intestinal development of tilapia.The supplementation of 400 mg/kg phytase could reduce the inclusion level of calcium dihydrogen phosphate by 0.6%.