Effects of Phytase Enzyme Supplementation on Protein Digestibility, Efficiency of Feed Utilization, Growth and Carcass Protein Content of Tambaqui (Colossoma macropomum)

Abstract

The success of intensive cultivation of tambaqui (Colossoma macropomum) is largely determined by the availability of high-quality feed. High-quality fish diets consist of fish meal produced from animal-based proteins in order to provide fish with the protein requirement. In intensive farming systems, feed costs account for 60–70% of total production costs. Due to fish meal's increasing cost; hence, less expensive ingredients are required to substitute fish meal. Soybean meal can be used as an alternative source of protein to substitute for fish meal due to its lower price and high protein content in fish diet. Phytate acid, one of the antinutritional materials contained within soybean meal, may decrease the nutrient content of feed by affecting with the fish's ability to absorb nutrients. The research aimed to examine the effect of adding the phytase enzyme to diet feed on increasing protein digestibility, efficiency of feed utilization and growth of tambaqui fish. The fingerlings of tambaqui used as test fish had an average weight of 3.85 ± 0.08 g/fish. The diet treatments in this study were phytase enzyme addition in diet with different doses, namely: A (0 FTU/kg feed), B (250 FTU/kg feed), C (500 FTU/kg feed), D (750 FTU/kg feed) and E (1000 FTU/kg feed). The results showed that phytase enzyme addition in diet significantly increased protein digestibility, efficiency of feed utilization, growth, and carcass protein content of tambaqui fish.  The most effectiveness phytase enzyme dose for tambaqui fish was 1000 FTU/kg feed, which resulted in highest values of ADCp, PER, FCR, and RGR at 68.46±0.28%, 2.27±0.05, 1.53±0.04, 74.59±0.45%, and 6.01±0.19%/day, respectively.