Preliminary Effects of Dietary Protein Levels on Muscle Quality and Digestive Enzyme Activities in GIFT-Oreochromis niloticus

Abstract

The effects of 10%, 15%, 20%, 25%, 30%, and 35% dietary protein levels onmuscle quality, and digestive enzyme activities in GIFT-O. niloticus were investigatedfor 12 weeks. A total of 720 juvenile GIFT-O. niloticus with initial wet body weight3.50±0.2 g and length 4.6±0.5 cm were randomly divided into six triplicate groupsaccording to the above protein levels. The results show that muscle quality of GIFT-O.niloticus increased with increasing muscle protein and lipid, amino acid level, fiberarea, and muscle water-holding capacity, but decreasing flesh fiber density. Theoptimal protein level was 25%. Protease activity increased first with the 10%–25%dietary protein level, followed by a decrease as the proportion increased. Inconclusion, the 25% dietary protein level was optimal to improve muscle quality andprotease activities, which could be regarded as a reference level to produce GIFT-O.niloticus feed.