ティラピアTilapia nilotica用飼料の適性添加油脂

概要

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Experiments were conducted to find out dietary lipids suitable as the practical feed of Tilapia nilotica, feeding them with the diets containing corn oil, soybean oil, pollock liver oil, beef tallow and medium chain triglyceride (MCT), respectively. The best weight gain and feed effciency were obtained in the fish receiving corn oil or soybean oil, both rich in 18: 2ω6. When corn oil was replaced by pollock liver oil, the growth rate was significantly decreased, indicating that pollock liver oil has no growth enhancing effect for the fish. The growth rate of fish, fed on the diet containing beef tallow or MCT as a basallipid, was inferior to that of the fish receiving 18: 1ω9, suggesting that the saturated fatty acids with carbon number 8 to 18 are not suitable for the basal lipid in diet of Tilapia nilotica. Feeding the diet containing 18: 1ω9 or beef tallow resulted in raising the level of 20: 3ω9 and an ω9 fatty acid with carbon number 22. Both corn oil and soybean oil were found to be more effective than pollock liver oil in reducing these levels. Thus, the dietary lipid suitable for Tilapia nilotica was found to be vagetable oils rich in 18: 2ω6 such as corn oil and soybean oil, and pollock liver oil had no dietary value for the fish unlike the other fish species.