マダイ親魚飼料の適性タンパク含量

抄録

A relatively long-term feeding experiment was conducted in order to compare the nutritional quality as a protein source between white fish meal and cuttlefish meal and to investigate an optimum protein level in diet of red sea bream broodstock for their reproduction. The percentage of buoyant eggs, total hatch and normal larvae obtained obtained was not so markedly different among eggs produced by the broodstock receiving respectively different diets with different protein levels except for those obtained from the broodstock given the diet containing cuttlefish meal as a protein source. In the broodstock fed on the control diet containing white fish meal (CP 45%) the average number of eggs produced during the experimental period was 205.1×10⁴ per fish, and 61.8% of these eggs were found to be buoyant. Wherase in the eggs produced by the broodstock receiving the cuttlefish meal diet the proportion of buoyant eggs was highest (83.5%) ammong the expeimental groups. In addition, the percentage of normal larvae available as fish seed was markedly improved from 24.2% to 79.5% by replacing white fish meal with cuttlefish meal as a protein source. Thus it has been confirmed again that cuttlefish meal is superior to white fish meal as a protein source in diets for red sea bream broodstock. An optimum protein level was not clearly defined in this expeiment, but was estimated to be around 45% judging from the present and previous results.