ハマチ用ドライペレットの開発

抄録

This study was conducted to develop a dry type of pellet with a high palatability and acceptabili-ty for yellowtail in order to reduce aquaculture wastes and the occurrence of various fish diseases due to raw fish feeding as well as to improve the quality of the cultured fish. After several feeding trials a completely new type of dry pellet (soft-dry) with a high palatability was succesfully produced by a twin extruder. This pellet contained 8-12% moisture but softer than ordinary hard pellets. Its dietary value was compared by feeding juvenile yellowtail weighing 340g on average with moist pellets prepared by mixing sardine and mash in a ratio of 8:2 or soft-dry for about 4 months in net cages (8 × 8 × 8m).
Fish fed the moist pellets grew up to about 980g, while the average body weight of fish fed soft-dry was 1180g, quite higher than those on moist pellets. The average feed gain ratio on dry matter basis during 4 months feeding was 1.50 for soft-dry and 1.79 for the moist pellet, respectively. The survival rate was more than 85% in both the groups. Thus, the newly developed soft-dry pellet has been found to have a nutritional quality superior to the moist pellet.