EFFECT OF PH, WATER STABILITY AND TOUGHNESS OF ARTIFICIAL DIETS ON THE PALATABILITY FOR JUVENILE ABALONE HALIOTIS FULGENS

An artificial diet containing abalone silage and other ingredients was adjusted to different pH values (pH 4, 5, 6, 7 and 8) to evaluate the effect of dietary pH on palatability for juvenile abalone. The pellet ed diets were offered to abalone for 12 h periods. Maximum food intake was observed for diets adjusted to pH 6 and 8, which also were the to ughest, with high water stability (low percentage of dry matter loss). The lowest intake was observed for the pH 5 diet, which had the lowes t water stability. A forward stepwise regression procedure showed that food intake can be predicted from a linear combination of toughness ( P < 0.05), whereas pH and water stability did not significantly add to the ability of the equation to predict food intake. It is concluded t hat pH alone did not affect abalone food intake. However, pH may have had an indirect influence on the diets, owing to toughness and other p ossible masked factors. Thus, one may be able to reduce production cos ts and avoid feed spoilage by using feeds with a low pH, as long as th ey have higher pellet toughness.