Effects of Replacing Soy Oil with Rubber Seed Oil on Growth Performance, the Blood and Liver Biochemical Indexes in Rainbow Trout (Oncorhynchus mykiss)

Purposes This experiment was conducted to study the effects of replacement of soy oil by extruded rubber seed oil on growth performance, the blood and liver biochemical indexes in rainbow trout.Method Four isoproteic and isolipidic experimental diets were formulated with 0%,4%,8% and 12% rubber seed oil replacing graded levels of soy oil, respectively. The experiment lasted for 10 weeks.Results (1) With the rubber seed oil replacement level increasing, the final body weight, weight gain, daily gain coefficient and protein efficiency ratio among all groups showed a trend of first increase and then decrease, and the highest was 8% group (P0.05),while the feed conversion rate was just opposite. The lowest was found in 8% group.(2) With the rubber seed oil replacement level increasing, the serum levels of low density lipoprotein cholesterin showed an increasing trend firstly, and then decreasing trend. And the highest was found in 8% group. The LDL-C/HDL-C in serum showed a gradual increasing trend, and it is in 12% group was significantly higher than that in 0% groups. (3) With the rubber seed oil replacement level increasing, the content of plasma nitric oxide and the activity of alkaline phosphatase were significantly increased, but the activity of plasma catalase decreased significantly. (4) The amino-N of the plasma in 0% group was significantly lower than that in the other groups. There was no significant difference in total protein, total amino acid, blood urea nitrogen, calcium, phosphorus, alanine aminotransferase activity of the plasma and ALT, aspartate aminotransferase of the liver among all groups (P0.05).Conclusions In summary, 4%-12% rubber seed oil supplementation can improve the growth performance and feed utilization ratio, and there is no obvious adverse effects on antioxidant capacity and lipid metabolism of the rainbow trout. The results also indicate that the suitable supplemental level is 8% in rainbow trout diets.