Studies on Fish Solubles-IV

Two feeding trials with rats were carried out to determine the possible presence of unidentified growth factor in fish solubles or whole meal. In the first test four groups of weanling rats, 3 males and 4 females each, were pair-fed for 6 weeks. To the control group was administered a basal diet containing casein at 15% level and to the comparable groups, test diets in which 15 percent of the amount of casein was replaced isonitrogenously by jack mackerel meat meal, liver solubles and liver meal from bluefin tuna respectively. The results showed that supplement with the two fish materials improved protein efficiency ratio (PER) of females in the latter half period though not in the former half period of feeding. The effect of fish materials was not observed in males during the entire feeding period. The second test was carried out similarly, but two levels of dietary protein, 15 and 8%, were provided and saury fish solubles was used as the sole substitute. At 15% level of protein, supplementing basal diet with the fish solubles had no effect on the growth of rats of both sexes, and this trend was uninfluenced by preventing coprophagy in rat. However, at 8% protein level, the fish solubles improved PER in females by 12 percent as the test period progressed.