Histidine requirement of snubnose silver pompano Trachinotus blochii

Abstract

Histidine is necessary for the formation and repair of tissues to mitigate the effects of cataract on some fish species. Although the requirements for dietary amino acids of several Trachinotus species have been reported, the quantitative histidine requirement for a cost-effective diet for snubnose pompano or Trachinotus blochii, a high value finfish species in the Philippines, has been limited. A 90-day growth experiment determined the dietary histidine requirement of juvenile snubnose pompano (0.19±0.03 g). Six isonitrogenous, isolipidic, and isoenergetic diets consisted of a control diet with 0% histidine inclusion level (basal histidine level of 0.65%) and five diets with histidine inclusion levels of 0.15 (0.80%), 0.3 (1.1%), 0.45 (1.55%), 0.6 (2.15%), and 0.75% (2.9%). To simulate the pompano whole-body amino acid composition, essential amino acids were added in the diet. Fifteen pompano juveniles per tank in three replicates were stocked randomly in 250-L fiberglass tanks and were fed to satiation for 90 d. When the dietary histidine level and percent weight gain were analyzed via quadratic regression, a dietary histidine level of 1.61 g per 100 g diet or 0.357 g per 100 g protein is required for juvenile snubnose pompano. Moreover, the occurrence of cataracts was not observed in fish fed all dietary treatments.