Effects Of Dietary Chicken Gut Meal Supplementation On Growth Performance,Digestibility And Some Immunological Indicators Of Common Carp(Cyprinus Carpio)

The shortage of fishmeal resources,high price and unsustainability have become constraints for aquaculture development.Chicken gut meal,with its low price and similar nutritional composition to fishmeal,is a promising alternative to fishmeal as a high-quality protein source.This experiment was conducted to investigate the effects of chicken gut meal as a substitute for fish meal and the addition of different levels of chicken gut meal to the feed on the growth,digestion,immunity,antioxidant and meat quality of common carp(Cyprinus carpio).This experiment was conducted in an indoor cement pond in a net tank with an 8-week culture cycle.(1)The fish used in this study were carp with an initial body weight of(66.84±1.42).These fish were randomly allocated into five groups of three replicates each,with 10 fish in each replicate.Five groups of feeds were formulated to contain equal nitrogen and fat levels(labeled D1,D2,D3,D4,D5),with a fish meal content of 4%in the control group(group D1)and varying percentages of fish meal substitution(0%,25%,50%,75%,and 100%)in the other groups.The possibility of replacing fishmeal with chicken intestinal meal was evaluated by exploring the effects of replacing fishmeal with chicken gut meal on carp through growth performance,digestion,immune antioxidant and serum biochemical indices.(2)The carp,initially weighing(57.34±0.13)g,were randomly allocated into five groups of 3 replicates with 10 fish per replicate.The experimental diets comprised of four isonitrogenous and isolipidic feeds,and one feed containing all-chicken gut meal with incremental levels of chicken gut meal inclusion at 0%,5%,10%,15%,and 100%,respectively.The effects of different levels of chicken gut meal in the feeds on carp were analyzed to investigate the optimum addition ratio of chicken gut meal in the feeds by examining growth,digestion,intestinal tissue structure,immunity,antioxidant,serum biochemical indexes,muscle nutrient composition and textural parameters.The main findings were as follows.1.Effects of replacing fish meal with chicken gut meal on growth performance and digestive enzyme activity of common carpThe replacement of fish meal by chicken gut meal significantly improved the growth performance of carp,and the final body weight,weight gain rate and specific growth rate of carp in the 50%,75%and 100%replacement groups were significantly higher than those in the control group(P<0.05).Feed coefficients were significantly lower(P<0.05)in all substitution groups than in the control group.The replacement of fish meal by chicken gut meal significantly increased PEP,α-AMS and LPS activities compared with the control group(P<0.05),and the PEP,α-AMS and LPS activities showed a trend of increasing and then decreasing with the increase of the replacement ratio and reached a peak at the D4 group(P<0.05).2.Effect of chicken gut meal replacing fish meal on immune,antioxidant and serum biochemical indexes of carpSOD activity was significantly higher in D3 and D4 groups than in the control group,CAT activity was significantly higher in D2,D3 and D4 groups than in the control group(P<0.05),and MDA content was not significantly different among the groups.AKP and LZM activities were significantly higher in D3 and D4 groups than in the control group(P<0.05),and ACP and AKP activities were significantly higher in D4 group than in the other groups.The ACP and AKP activities in the D4 group were significantly higher than those in all other groups.The levels of total serum protein,albumin,total cholesterol and triglyceride in carp were not significantly different between the groups(P>0.05).With the increase in the proportion of chicken gut meal replacing fish meal,the AST and ALT activities in carp serum tended to increase,with the AST activities in the D4 and D5 groups significantly higher than those in the control group,and the ALT activities in the D3,D4 and D5 groups significantly higher than those in the control group(P<0.05).3.Effect of different levels of chicken gut meal in the feed on growth performance and intestinal digestibility of carpThe final body weight,weight gain rate and specific growth rate of CGM 15%and CGM 10%groups were significantly higher than those of the control group(P<0.05).final body weight,weight gain rate and specific growth rate of CGM 100%group were higher than those of the control group,but there was no significant difference(P>0.05).plasma growth hormone and insulin growth factor concentrations of CGM 15%group were significantly higher than those of the other groups(P<0.05).The intestinal PEP,AMS and LPS activities in the CGM 10%,CGM 15%and CGM 100%groups were significantly higher than those in the control group(P<0.05).intestinal muscle thickness in the CGM 15%group was significantly higher than that in the control group,villi height in the CGM 10%and CGM 15%groups was significantly higher than that in the control group(P<0.05).The CGM 15%group exhibited a significant increase in intestinal muscle layer thickness compared to the control group(P<0.05).In addition,both the CGM 10%and CGM 15%groups displayed a substantial rise in villi height when compared to the control group(P<0.05).Moreover,the CGM 15%group demonstrated a significant increase in villi width when compared to the control group(P<0.05).The intestinal muscular layer thickness,villi height and villi width all peaked in the CGM 15%group.4.The effects of different levels of chicken gut meal in the feed on antioxidant,partial immunoenzyme activities,and serum biochemical indexes of common carpThe addition of different levels of chicken gut meal in the feed had a significant effect on antioxidant and some immune enzyme activities of carp(P<0.05).the ACP activity was significantly higher in the CGM 10%,CGM 15%and CGM 100%groups than in the control group(P<0.05),AKP activity was significantly higher in the CGM 10%and CGM 15%groups than in the control group(P<0.05),and LZM ACP,AKP and LZM activities were all peaked in the CGM 15%group.The addition of chicken gut meal to the diet could increase the T-AOC,T-SOD and CAT activity of carp liver,and showed a trend of increasing first and then decreasing.(P<0.05),and the MDA contents of CGM 5%,CGM 10%and CGM 15%groups were significantly lower than those of the control group(P<0.05).Serum triglyceride,total cholesterol content,AST and ALT activities were lowest in the CGM 15%group but highest in the CGM 100%group(P<0.05).5.Effects of adding different levels of chicken gut meal to the feed on the nutritional composition and textural characteristics of carp muscleThe contents of crude protein and crude fat were significantly higher in the CGM 10%and CGM 15%groups than in the control group(P<0.05),while the contents of ash and moisture were not significantly different between the groups(P>0.05).Compared with the control group,the hardness,elasticity,cohesiveness,gumminess and chewiness of carp muscle were higher after the addition of chicken gut meal to the feed,and the chewiness of CGM 5%,CGM 10%,CGM 15%and CGM 100%was significantly higher than that of the control group(P<0.05).The peaks of hardness,elasticity,cohesiveness,gumminess and masticatory properties were all in the CGM 15%group.6 The impact of different levels of chicken gut meal added to feed on the intestinal microbial community structure of carp.Adding an appropriate amount of chicken gut meal to the feed can reduce the diversity of intestinal bacteria in carps,but it has the effect of improving the structure of intestinal bacteria.Compared with the addition of 0%,5%,15%,and 100%of chicken gut meal,the abundance of pathogenic bacteria in carps’ intestines is lowest and the relative abundance of beneficial bacteria is highest when the addition is 10%.Moreover,even when the addition of chicken gut meal is 100%,the relative abundance of beneficial bacteria in the intestines of carps does not decrease.Under the conditions of this experiment,adding 10%chicken gut meal to the feed has the best improvement effect on the structure of the intestinal bacteria in carps.