ニジマスの産卵に及ぼす低タンパク・高カロリ-および必須脂肪酸欠乏飼料の影響〔英文〕

概要

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A feeding experiment was conducted to investigate effects of quality of diets, given to rainbow trout broodstock for 3 months before their spawning, on the reproduction and egg quality by feeding various diets, with different levels of protein and lipid or a diet without supplemental essential fatty aid (EFA). The growth rate and feed efficiency were high in the broodstock receiving the diet containing 36% protein and 18% lipid and in addition eyed rate and total hatch were also high in the eggs produced by the broodstock of this group. The growth and feed efficiency in the fish kept on the diet containing 28% protein becamen slow from around 60 days after feeding. Feeding the diet containing beef tallow as a part of energy source gave good results with regard to reproduction, comparable to those obtained in the broodstock fed on a commercial high protein diet. The EFA-deficient diet was found to result in low growth rates, eyed eggs and hatchability, and these results were also found to be effectively improved by supplementing ethyl linoleate to the diet, indicating importance of EFA for reproduction. The results of this study have demonstrated that egg quality was greatly affected by the nutritional quality of diets given to rainbow trout broodstock for a short-period of 3 months before their spawning.