報告書番号

U99039

タイトル（和文）

ヒラメ若魚、未成魚飼料における脂肪の利用能

タイトル（英文）

Utilization of dietary lipid in young and immature Japanese flounder

概要 （図表や脚注は「報告書全文」に掲載しております）

飼料のタンパク質含量(CP)を45ならびに55%とし、それぞれ脂肪含量を3段階に変化させた飼料で初期体重55gのヒラメ若魚を12週間、同様のCPで脂肪をそれぞれ2段階に変化させた飼料で初期体重240gのヒラメ未成魚を20週間飼育した。若魚における終了時体重、増重率はCP55%の飼料区で高く、脂肪による成長の改善は認められなかった。タンパク質効率は、CP55%では脂肪含量の増加に伴なって上昇する傾向を示した。未成魚の成長はCP55%で脂肪含量が最も低い区で他より優れていたものの、タンパク質効率はCP45%で脂肪含量が最も高い区で有意に高かった。若魚、未成魚とも、飼料脂肪の増加に伴なって血中トリグリセリドの著しい上昇を引き起こした。また、飼料脂肪の増加に伴なって肝臓の肥大ならび肝臓や消化管への脂肪の蓄積が観察された。脂肪含量が最も高い飼料区では、これに加え筋肉中の脂肪の有意な増加が認められ、特に縁側筋肉では他に比べ著しく高くなった。

概要 （英文）

Effects of dietary protein and lipid levels on growth and body composition of Japanese flounder were examined. Young fish of about 55 g in initial body weight were fed six extruded diets with dietary protein levels of 45 and 55 % and three lipid levels each to satiation twice daily, 6 days a week for 12 weeks at 20℃ with triplicate groups per dietary treatment. Four diets with the same protein level (45 and 55 %) and two lipid levels each were supplied to immature fish of 240 g of initial body weight for 20 weeks with duplicate groups per treatment. The final body weight and weight gain of young fish fed the diets containing 55 % protein were higher than those of fish fed the 45 % protein diets, although both parameters were statistically identical among dietary treatments. The dietary lipid level did not affect these parameters regardless of the protein level. Protein efficiency ratio improved as the lipid level of the diet increased in the 55 % protein diets. The growth of immature fish fed the diet with 55 % protein and the lowest lipid level was higher than that in the other dietary treatment. However, protein efficiency ratio was the highest in the dietary group with 45 % protein and the highest lipid level. Both in two feeding trials, triglyceride content of the cultured fish increased depending on the dietary lipid level, while the other hematological and hematochemical parameters were not affected seriously by the dietary composition. Liver weight and hepato-somatic index of the cultured fish tended to increase in accordance with increasing dietary lipid level both in two trials. Crude lipid content of the liver and digestive tract appeared to depend on dietary lipid level. The diet containing 45 % protein and the highest lipid level resulted in significantly higher crude lipid content of the eye-side muscle as well as Engawa muscle of the cultured fish than those in the other dietary groups.

報告者

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