Effect of Feed Ingredients on Digestive Enzyme Secretion in Fish

In response to the limitation in the global supply of fish meal, the traditional protein source used in aquaculture feed, efforts have increasingly been focused on the use of alternative protein sources of plant origin. However, plant ingredients may cause growth retardation in aquaculture fish species. Feed nutrients must be digested for their utilization, and so pancreatic digestive enzymes have essential roles for the digestion. Also cholecystokinin (Cck) is known to be a hormone that stimulates the secretion of digestive enzymes in vertebrates. To improve the utilization of plant based diets in fish, we investigated the effects of various feed ingredients on secretion of digestive enzymes in red sea-bream Pagrus major and yellow-tail Seriola quinqueradiata, which are commercially important aquaculture species in Japan. Supplementation of the enzyme stimulation factor, although not identified yet, may improve the utilization of plant based diets in aquaculture fish species.