Effects of replacement of fish oil with soybean oil on growth performance, immunity and tissue enzyme activity of rainbow trout Oncorhynchus mykiss
XU Qi-you, xu Hong, LI Chan, YANG Ping, WANG Chang-an
1. Heilongjiang River Fisheries Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; 2. School of Life Science and Technology, Dalian Fisheries Univ. , Dalian 116023, China
Abstract: Effects of replacement of fish oil with soybean oil on growth performance and immunity in rainbow trout Oncorhynchus mykiss were studied. The fish was fed the diets containing 18% fish oil（ G1 ）, 6% fish oil ＋ 12% soy oil（G2）, 3% fish oil ＋ 15% soy oil（G3） and 18% soy oil（G4） with triplication for 8 weeks at water temperature from 12.5 - 16.5 ℃, and dissolved oxygen content from 7.8 - 10 mg/L. There were no significant differences in final body weight, final body length, condition factor, special growth rate （SGR）, feed conversion ratio （FCR） and daily gain in the treatment groups（ P 〉 0.05）. The fish in the group G2 had 7.99% higher final body weight, 11.85% higher SGR, 13.89% daily weight gain and 12.82% lower FCR than the fish in the group G1 did. There were significantly higher plasma AKP, liver AKP（ P 〈 0.05 ）and liver ACP, kidney ACP（ P 〈 0.01 ）in G3 than those in G1. Liver lysozyme was found to decrease in G4 （ P 〈 0.05 ）, G2 and G3 （ P 〉 0.05 ）. Lower gill MDA was observed （P 〈0.05 or P 〈0.01 ）in G2, G3 and G4, and higher liver CAT in G3 （P 〈0.05）and lower kidney CAT in G3, and G4 （ P 〈 0.05 ）, indicating that growth performance was not influenced by replacement of fish oil with soy oil, but the immunity decreased; the best growth performance was observed in the group of 6% fish oil ＋ 12% soy oil.
2009, Vol. 24 
