The effects of partial replacement of white fish meal by poultry by-product meal and addition of bile acid in feed on growth, digestibility, and serum enzyme activities of the Chinese soft-shelled turtle

Abstract

Four isonitrogenous experimental diets were used to test the effects of replacing white fish meal with poultry by-product meal (PBM) and adding bile acid (BA) in a commercial feed for the Chinese soft-shelled turtle Pelodiscus sinensis with 9 replicates and 6 turtles in a 60-day study. Diet 1 contained white fish meal as a main protein source (100 %). Diet 2 contained white fish meal (60.8 %) and PBM (39.2 %) as the protein source. Diets 3 and 4 comprised the addition of 1 g kg−1 of bile acid to diets 1 and 2, respectively. Compared to diet 1, the glutamic-pyruvic transaminase level in the turtles fed with diet 2 were not augmented significantly as was the case for glutamic oxalacetic transaminase level. The relative growth rate and specific growth rate in diet 2 were the same as those of diet 1. The apparent digestibility coefficient for lipid (ADCL) tended to decrease after that white fish meal was partially replaced. The values of weight gain, relative growth rate, feeding rate, specific growth rate, apparent digestibility coefficient for dry matter, ADCL and apparent digestibility coefficient for protein (ADCP) of the turtles on diet 4 (1 g kg−1 bile acid added in diet 2) increased by 28.1, 28.8, 10.1, 20.6, 1.7, 0.6 and 0.3 %, respectively, compared to those on diet 2. The combined effects of bile acid and PBM on the growth of turtles was even more effective than the whole white fish meal diet, by increasing feeding rate 7.4 %; it decreased the amounts of crude lipids (by 22.8 %), glutamic-pyruvic transaminase (by 1.9 %), and alkaline phosphatase (by 3.9 %). Therefore, replacing 39.2 % of white fish meal with PBM and adding BA was feasible in turtle feed.