Practical Culture of Yellowtail with a Newly-developed Soft-dry Pellet
1997 Volume 45 Issue 1 Pages 123-129
Details
1997 Volume 45 Issue 1 Pages 123-129
Feeding experiments were conducted for 2 years in commercialscale net cages (10×10×8m) in order to evaluate the dietary value of a newly developed soft-dry pellet (SDP) for juvenile and adult yellowtail.
Three kinds of SDP were prepared from the same ingredients, but slightly varying their contents to produce diets containing 43-47% protein and 18-23% lipid. The diets were offered to three size groups of fish, both in Expt. I (average weights: 32, 38 and 54g) and in Expt. II (average weights: 34, 35 and 44g), from June to October. The fish in Expt. I grew upto 677, 750 and 1020g respectively; the corresponding feed gain ratios being 1.07, 1.08 and 1.19 and the survival rates being 70.2, 75.4 and 88.0%. In Expt. II the final fish weights were 750, 757 and 992g respectively; the related feed gain ratios were 1.68, 1.95 and 1.87 and the survival rates were 89, 91 and 95.2%. Dietary value of SDP at low water temperatures was also investigated (EXpt. III) by feeding 3 groups of 2-year old fish having average weights of 677, 750 and 1020g, for about six months from October to May. This experiment was the extension of Expt. I and the fish grew upto 1600, 1600 and 2000g respectively and the feed gain ratio ranged from 1.49 to 1.76.
These results demonstrate that the newly developed SDP is comparable or possibly superior in dietary value to raw fish and moist pellets which are commonly being used as feeds for yellowtail.
