Effects of Replacing Fish Oil with Rubber Seed Oil on the Growth, Body Composition and Biochemical Indexes in Cyprinus carpio

Purpose In order to investigate the effects of replacing dietary fish oil with rubber seed oil on growth performance, body composition and biochemical indexes in Cyprinus carpio.

Method Five isoproteic and isolipidic experimental diets were formulated with 0%, 25%, 50%, 75% and 100% rubber seed oil replacing graded levels of fish oil, respectively. The experiment lasted for 10 weeks.

Results (1) There was no significant difference in weight gain, weight gain and daily weight gain of 0% and 25% groups (P>0.05), but there was significantly higher than that in 50%, 75% and 100% group (P<0.05). 75% and 100% group feed efficiency and protein efficiency were significantly lower than other treatment groups (P<0.05). (2) The total cholesterol and low density lipoprotein cholesterol of the serum in the 0% group were significantly higher than those in the 50%, 75% and 100% groups (P<0.05). There was no significant difference in serum triglyceride and high density lipoprotein cholesterol in different feed treatment groups (P>0.05). (3) With the increase of the ratio of rubber seed oil to fish oil in feed, the activity of alanine aminotransferase in liver increased first and then decreased. Among them, 25% and 50% group were significantly higher than other treatment group. (4) 100% group plasma superoxide dismutase and alkaline phosphatase activity was significantly lower than that of 0% and 25% group. Similarly, plasma catalase activity in the 100% group was significantly lower than that in the 25% and 75% groups. The liver total antioxidant capacity of 25% and 50% group was significantly higher than that of 100% group. Liver alkaline phosphatase activity in 75% group was significantly higher than that in 0%, 25% and 50% groups.

Conclusions There were no adverse effects on the growth performance and feed utilization when the replacement level of 25%. However, when the rubber seed oil replacement is more than 50%, it can hinder the growth of C. carpio, and endanger the health of the liver. The results also indicate that the suitable adding amount of rubber seed oil in carp feed was 1.6%-3.2%.