Study On The Application Of Animal Protein And Plant Protein In Largemouth Bass(micropterus Salmoides)diets

EXP.1 Study on replacement of fish meal with two kinds of animal protein sources in largemouth bass(Micropterus salmoides)dietIn order to investigate the feasibility and appropriate substitution level of chicken plasma powder and hydrolytic chicken hemoglobin powder in largemouth bass diet for the replacement of fish meal,imported fish meal was used as the main protein source and 51% of the fish meal was used as a control named FM group.Chicken plasma powder(CPP)and hydrolytic chicken hemoglobin powder(CHP)were used to replace the fish meal in the feed.The replacement levels were set to 9.80%,19.61%,and29.41%,respectively.The replacement groups were named PP1(9.80%),PP2(19.61%),PP3(29.41%),HP1(9.80%),HP2(19.61%),and HP3(29.41%).A total of 7isonitrogenous and isoenergetic diets were formulated.Each diet was randomly assigned to triplicate tanks of 25 fish with initial body weight(49.47±0.07)g and the feeding trial lasted 84(12 weeks)days.During the test period,two feedings were performed every day using the apparent satiety feeding method(8:00 and 16:00).With the increase of fish meal levels of two kinds of animal protein sources in feed,the feeding rate and specific growth rate of each alternative group gradually decreased,PP1 group and there was no significant difference in the FM group(P>0.05).The other groups were significantly smaller than the FM group(P<0.05).The feed efficiency ratio and protein efficiency ratio of the chicken plasma powder substitute group first increased and then decreased,and the substitute groups in the hydrolytic chicken hemoglobin powder showed a tendency to decrease.The feed efficiency of the PP1 group,the PP2 group,and the HP1 group had no significant difference with the FM control group(P>0.05),and the highest feed efficiency was found in the PP2 group.The protein digestibility,fat digestibility,and protein deposition rate of each of the two protein source substitution groups decreased with increasing substitution rate,of which the PP1 group,PP2 group,and HP1 group had no significant differences with the FM control group(P>0.05).The crude protein content of whole fish was not significantlydifferent between the PP1 group and the HP1 group(P>0.05),but was significantly higher than that of the other alternative groups(P<0.05).Serum lysozyme activity in chicken plasma powder and hydrolytic chicken hemoglobin powder substitute groups decreased as the proportion of substituted fish meal increased.There was no significant difference between PP1 group,PP2 group and HP1 group and FM group(P>0.05).There was no significant difference in serum complement activity between the PP2 group and the FM group(P>0.05).Since the specific growth rate of experimental fish was getting smaller and smaller as the feeding rate of each alternative group decreased,only the chicken plasma powder 9.80% level substitution group had no significant difference with the control group.However,when feed efficiency,protein efficiency,protein deposition rate and non-specific immunity were used as evaluation indicators,chicken plasma powdera replace 19.61% of fish meal in feed,and chicken blood cell meal replace 9.80% of fish meal did not cause any negative effect on largemouth bass.The feed efficiency,protein efficiency and amino acid digestibility of the replacement group with a level of 19.61% of chicken plasma powder were better than those of fish meal control group.Therefore,it can be concluded that the optimum replacement level of chicken plasma powder in largemouth bass diets is 9.80% to 19.61%,and the level of hydrolytic chicken hemoglobin powder replacing fish meal should be within 9.80%.EXP.2 Nutritional value evaluation of four types of soybean meal in diets for largemouth bass(Micropterus salmoides)A feeding trial was conducted to evaluate the nutritional value of dehulled soybean meal(DSM),fermented soybean mealⅠ(FSMⅠ),fermented soybean mealⅡ(FSMⅡ)and enzyme-treated dehulled soybean meal(EDSM)used in diets for largemouth bass(Micropterus salmoides).On the basis of analysis of the relative components of the above soybean meal,four isonitrogenous and isoenergetic diets were formulated with equal nitrogen level.Each diet was randomly assigned to triplicate tanks of 30 fish with an initial average body weight of(32.38±0.01)g.Growth performance,body composition,non-specific immune parameters and intestinal morphology were analyzed after 67 days’ feeding.Results showed that the final body weight and specific growth rate of the EDSM were significantly higher than those of the FSMⅠ(P<0.05)which was significantly higher than the DSM and FSMⅡ(P<0.05),and no significant difference was observed between the DSM and FSMⅡ(P>0.05).Feed efficiency ratioand protein digestibility of the EDSM were significantly higher than those of the FSMⅠ(P<0.05)which was not significantly different from the FSMⅡ(P>0.05),while the feed efficiency ratio and protein digestibility were reduced in the diet of DSM(P<0.05).No significant difference was observed in feed efficiency ratio between the DSM and FSMⅡ(P>0.05),but the DSM significantly reduced protein digestibility(P<0.05).Different kinds of soybean meal have no effects on crude protein of whole fish and muscle and the crude fat of muscle(P>0.05).The crude lipid in whole fish of the DSM was significantly higher than that of the other groups(P<0.05).Serum lysozyme activity was significantly higher in the EDSM and FSMⅠ than in the FSMⅡand DSM(P<0.05).No significant difference was found in serum lysozyme activity between the FSMⅡ and DSM(P>0.05).Serum complement activity of the DSM was significantly lower than that in the FSMⅠ and EDSM(P<0.05).The intestinal morphology showed that the folds of midgut were more irregular than those in the other three groups,and the distal intestine folds were irregularly located with the widening of the submucosa in the DSM.Meanwhile,the central stroma of the mucosal folds in the hindgut became wider,and part of the epithelial cells became damaged.While there were no abnormal midgut and hindgut morphology in the FSMⅠ,FSMⅡand EDSM.In conclusion,the methods of enzymatic treatment and fermentation can remove some anti-nutritional factors in soybean meal,which contribute to improving feed utilization and maintaining the normal intestinal morphology.Fermented and enzyme-treated soybean meal are superior to dehulled soybean meal in nutritional value of largemouth bass,meanwhile,the enzyme-treated dehulled soybean meal was better than fermented soybean meal.