Effects of egg product on growth performance, muscle nutrients, and intestinal microflora of Procambarus clarkii

To evaluate the application effect of spray-dried egg product in the diet of Procambarus clarkii, we formulated five isonitrogenous and isoenergetic diets containing 0% (Control group), 2.0%, 4.0%, 6.0% and 8.0% spray-dried egg product, which replaced 0% (CON), 25% (R1), 50% (R2), 75% (R3) and 100% (R4) fishmeal, respectively, to feed the shrimps Initial body mass (9.02±0.12) g for six weeks. The results show that there were no significant differences in the specific growth rate, feed conversion ratio, feeding rate, survival rate and hepatosomatic index among all the groups (P>0.05). The weight gain rate in R4 group decreased significantly compared with the CON group (P<0.05). The contents of crude protein, essential amino acid and total amino acid in abdominal muscle in R4 group increased significantly compared with the CON group (P<0.05). The contents of crude fat and ash in muscle in R2, R3 and R4 groups were significantly higher than those in the CON group (P<0.05). There were no significant differences in the contents of 17 hydrolyzed amino acids in muscle among all the groups (P>0.05). Compared with the CON group, the intestinal protease activities increased significantly but the amylase activities decreased significantly in egg product supplementation groups, and the intestinal lipase activity increased significantly in R3 and R4 groups (P<0.05). The serum alkaline phosphatase activity and total protein content in R2, R3 and R4 groups increased significantly than those in the CON group (P<0.05). The bacterial abundances of Clostridium sensu stricto and Lysobacter in R3 group were significantly higher than those of the other groups, while the bacterial abundance of Streptococcus in R4 group was significantly higher than that of the other groups (P<0.05). In conclusion, when the diet of P. clarkii contains 6% fishmeal, the spray-dried egg product can replace 75% fishmeal.