Effects Of Poultry By-Product Meal On Growth,Muscle Quality And Gut Health Of Crayfish (Procambarus Clarkii)

In this study,we investigated the effects of replacing fish meal with chicken meal at different ratios in the feed on the growth,muscle quality and intestinal health of Procambarus clarkii with an initial body weight of(6.00±0.00)g.Five isonitrogenous and isoenergetic test diets with chicken meal replacing fish meal 0%,25%,50%,75% and 100%were set up,and the proportion of fish meal in the basal diet was 20% for FM group,CM25 group,CM50 group,CM75 group and CM100 group,respectively,with three replicates of50 shrimps in each group.The culture experiments were conducted in pond nets(2.0 m×1.0m×1.5 m)at the experimental base of Guolian crayfish breeding and breeding base in Yiyang City,Hunan Province,with feeding twice a day(07:00and18:00)at 5%-8% of the body weight of the test shrimp,and the experiments lasted for 8 weeks.The results of the study were as follows.1.Effect of chicken meal substitution for fish meal on the growth and serum biochemistry of Procambarus clarkii(1)As the level of chicken meal substitution increased,the weight gain rate and specific growth rate of Procambarus clarkii showed a trend of first increasing and then decreasing,and the weight gain rate and specific growth rate of CM100 group were significantly lower than those of FM group(P<0.05).The bait coefficient of Procambarus clarkii showed a trend of decreasing and then increasing,with the CM100 group significantly higher than the FM group(P<0.05).There was no significant difference in survival rate between the groups(P>0.05).(2)As the level of chicken meal substitution increased,there was no significant difference in liver-to-body ratio,organ-to-body ratio and fatness among the groups of Procambarus clarkii(P>0.05).(3)There was no significant difference in moisture and crude fat of Procambarus clarkii(P>0.05).Crude protein showed a decreasing trend,with the CM75 and CM100 groups significantly lower than the FM group(P<0.05).(4)There was no significant difference in triglyceride content in the haemolymph of crayfish between the treatment groups(P>0.05).Total cholesterol content showed a trend of decreasing and then increasing,with the CM25 group being significantly lower than the CM100 group(P<0.05).There was no significant difference between creatinine and FM group levels in each treatment group(P>0.05).Glutathione and ghrelin activities tended to increase,with the CM75 and CM100 groups being significantly higher than the FM group(P<0.05).LDL cholesterol and HDL cholesterol contents were not significantly different between the experimental groups and the FM group(P>0.05).There was no significant difference in glucose content among the treatment groups(P>0.05).(5)There was no significant difference(P>0.05)in the albumin content in the haemolymph of Crassostrea virginica between the treatment groups.The complement 3 and complement 4 contents of CM25,CM50 and CM75 groups were not significantly different from the control group(P>0.05),and CM100 group was significantly lower than the control group(P<0.05).Lysozyme activity showed a decreasing trend,with the CM75 and CM100 groups significantly lower than the FM group(P<0.05).Acid phosphatase and alkaline phosphatase activities were not significantly different between the treatment groups(P>0.05).2.Effect of chicken meal replacing fish meal on muscle quality of Procambarus clarkii(1)As the level of chicken meal substitution for fish meal increased,the overall muscle tissue structure of Procambarus clarkii was more complete in all treatment groups.The muscle fiber area and muscle fiber diameter of Procambarus clarkii showed a trend of first decreasing and then increasing,and there was no significant difference between each experimental group and FM group(P>0.05).Myofiber density showed a trend of increasing and then decreasing,and there was no significant difference between the experimental groups and the FM group(P>0.05).(2)As the level of fish meal substitution by chicken meal increased,there was no significant effect on total superoxide dismutase activity,glutathione peroxidase activity and malondialdehyde content in muscle(P>0.05).Catalase activity in muscle showed a decreasing trend,with the CM75 and CM100 groups being significantly lower than the FM group(P<0.05).(3)With the increase in the level of fish meal substitution by chicken meal,the lysine content in the muscles of Procambarus clarkii showed a decreasing trend,with the CM100 group being significantly lower than the FM group(P<0.05).the methionine content of the CM75 and CM100 groups was significantly lower than that of the FM group(P<0.05).All other amino acid contents in all experimental groups were not significantly different from those in the FM group(P>0.05).The total amino acid content of muscle and total essential amino acid content of each treatment group were not significantly different(P>0.05).3.Effect of chicken meal replacing fish meal on the intestinal health of Procambarus clarkii(1)As the level of chicken meal substitution for fish meal increased,the intestinal villi of all treatment groups were intact and there was no necrosis and shedding of the intestine.As can be seen from Table 4-1,with the increase in the level of chicken meal substitution for fish meal,the height of the villi in the muscles of each experimental group was significantly higher than that of the FM group(P < 0.05).The thickness of muscle layer in CM75 and CM100 groups was significantly lower than that in FM group(P < 0.05),and there was no significant difference between CM25 and CM50 groups and FM group(P > 0.05).(2)As the level of fish meal substitution by chicken meal increased,amylase activity and trypsin in the intestine were not significantly different among the groups(P>0.05).lipase activity in the CM75 and CM100 groups was significantly lower than that in the FM group(P<0.05).(3)The dominant bacterial groups of Procambarus clarkii in order of relative abundance were Firmicutes(74.9%-92.0%),bacteroidota(2.9%-15.4%)and Proteobacteria(3.1%-7.5%),etc.The CM25 and CM50 groups had the highest percentage of Firmicutes,while the CM25 and CM50 groups had the highest percentage of Firmicutes and Proteobacteria.The CM25 and CM50 groups had the highest rates of Proteobacteria,while the CM25 and CM50 groups had the lowest rates of bacteroidota and Proteobacteria.At the genus level,the dominant genera in the intestine of each treatment group in order of relative abundance were [Anaerorhabdus]＿furcosa＿group(22.4%-34.5%),Rsa Hf231(16.4% to29.4%),Candidatus Bacilloplasma(15.5%-31.7%),etc.The richness and diversity of the flora increased with the amount of chicken meal substituted for fish meal.Conclusion: The optimum percentage of chicken meal to replace fish meal in the diet of crayfish was 25%-50%.Suitable substitution of chicken meal for fish meal in the diet of crayfish can improve its growth performance without negatively affecting the muscle quality of crayfish.No pathological changes were found in the intestinal tissues of the crayfish and the suitable substitution would not destabilise the intestinal environment,while adding too much chicken meal would negatively affect the intestinal digestion and absorption of the Procambarus clarkii.