エゾアワビの栄養要求 ＩＩＩ アワビ飼料におけるたんぱく質の至適含量

Abstract

A feeding experiment was carried out by feeding juvenile abalone Haliotis discus hannai with diets containing casein or white fishmeal as a protein source at different protein levels (0-55%) for 50 days at a water temperature of 20°C in order to determine an optimum protein level in the diet for the abalone. In the abalone receiving the casein diets, feed conversion efficiency (FCE) and protein reten-tion were found to be proportional to the dietary protein levels and reached plateau at a 38% protein level where the values for PER and NPU were 2.4 and 48, respectively. The maximum rate of protein retention was obtained at a 10% protein level in the casein diet and at a 22% protein level in the white fishmeal diet. In addition, growth, FCE and protein retention in the abalone fed on the white fishmeal diets were all far inferior to those obtained by the casein diets. The values for PER and NPU obtained with the white fishmeal diets were about one half of those obtained with the casein diets. The difference in nutritional quality be-tween both of these protein sources was postulated to be due to low digestibility of white fishmeal protein in the abalone. When casein is used as a protein source, an optimum protein level in the practical diets for juvenile abalone is estimated to be around 20-30% based on the growth rate, FCE, protein retention and NPU.