Amylase activity in our experiments decreased from M to PL and then increased III 3–5
in PL , independently of the diet. Lovett and Felder (1990b) obtained similar results in 10
the same species feeding on live food. These authors found a significant ontogenetic
change in digestive enzyme activity though they held the postlarval diet constant in their
study. Increased amylase activity in PL stage has been found in Penaeus monodon 10
(Fang and Lee, 1992) and in L. vannamei, (Brito, unpublished results). Lovett and
Felder (1990b) stated that the substantial increase in amylase activity observed during
postlarval development in L. setiferus might be a response to low levels of carbohydrate
in the diet. Rodr´ıguez et al. (1994) also explained high levels of amylase activity in
early myses of M. japonicus as a function of low substrate availability. Mixed diets used
in our experiments caused a decline in amylase activity, showing that perhaps the
combination of starch from different origins enhances digestibility of diet starch. Le
Moullac and Van Wormhoudt (1994) remarked on the importance of the origin of the
starch as a factor of amylase variation in L. vannamei larvae.