Nutrient and amino acid profiles of egg and larvae of Asian seabass, Lates calcarifer (Bloch)

摘要

Fertilized eggs and developing larvae of hatchery reared Asian seabass, Lates calcarifer ( Bloch), were analyzed to determine the changes occurring in their proximate and amino acid ( AA) composition. The fertilized dry egg weighed 31 mug and contained 13.71 mug (44%) protein, 8.48 mug (27%) lipid and 0.657 J of gross energy. Dry weight decreased by 39% during hatching. The protein, lipid and carbohydrate nutrients decreased by 4.86, 4.15 and 0.09 mug, respectively from egg to 2-days post hatching (dph) larvae (pre-feeding). The protein content of the spawned eggs and larvae were hydrolysed to AA in the laboratory. The fertilized eggs had a total AA content of 42% of their dry weight. The egg contained 1.287 mug, 1.132 mug, 0.964 mug, 0.942 mug, 0.787 mug and 0.713 mug of leucine, lysine, arginine, valine, threonine and phenylalanine, respectively and these six indispensable amino acids (IAA) constituted approximately 78% of the total IAA. In the early feeding stages of L. calcarifer larvae, the ratio of IAA/DAA increased from 0.797 in the pre-feeding stage to 1.632 after 2 days of feeding. During larval growth of L. calcarifer, the percentage contribution of isoleucine and leucine to total IAA contents increased, while it decreased for lysine, phenyl alanine and arginine. L. calcarifer larvae were found to have proteins, which are rich in glutamic acid, leucine and lysine, and poor in threonine and histidine, suggesting high dietary leucine and lysine IAA requirement.