Evaluation of growth performance and nutritional quality of diets using digestive enzyme markers and in vitro digestibility in Siamese fighting fish (Betta splendens Regan, 1910)

Digestive enzymes and their effects on in vitro digestibility of feeds and feedstuffs, as well as on growth performance quality were studied in Siamese fighting fish (Betta splendens Regan, 1910). The specific activities of total protease, amylase, trypsin and chymotrypsin increased during development and were higher in females than in males at maturation (P < 0.05). The activity ratio of trypsin to chymotrypsin corresponded to fish growth, and showed lower values in females than in males. White muscle levels of RNA decreased during development, with females having higher levels than males, while the protein levels increased with no difference between sexes. In the oocytes, trypsin-like and chymotrypsin-like specific activities were very low, and the concentrations of RNA, protein and protein/lipid ratio were higher than in the muscle. For in vitro digestibility, wheat gluten, soybean meal and fish meal were among good protein sources while the meals from peanut, fish and soybean were good carbohydrate sources. Golden apple snail meat was a good source for both protein and carbohydrate. The crude enzyme extracts from different growth stages and sexes had different abilities to digest the same feeds and feedstuffs. This will make it possible to preliminarily study the authenticated nutritional quality of raw materials for future feed formulations for B. splendens.Keywords: Betta splendens, digestive enzymes, feedstuff, in vitro digestibility, muscle quality, oocyte quality, Siamese fighting fishAfrican Journal of Biotechnology Vol. 12(14), pp. 1689-1702