An Improvement of Carcass Quality of Harvested Cage Cultured Catfish (Mystus nemurus) by Increasing Protein Level in the Diets

Abstract

Two diets containing 40% protein, P/E ratio 1.30 g/kcal (high protein) and 34% protein, P/E 1.07 g/kcal (low protein), which produced the best growth at our previous experiment, were fed to Mystus catfish to determine their carcass quality. The fish ranging from 40.14 g to 42.64 g in size was grown in commercial fish cages (4x4x1.5 m) at a density of 50 fish per m3 for 90 days. The fish were fed the experimental diets at libitum twice daily, at 9.00 and 16.00. The harvested fish was evaluated for carcass quality characteristics and growth performance. Edible flash, dressing percentage and water holding capacity of harvested fish were higher for the fish fed higher protein diet than that for lower protein diet (P<0.05); but carcass waste was higher for the fish fed lower protein diet than that for higher protein diet (P<0.05). There was no significant different in hematosomatic index between the two fish groups (P>0.05). Proximate composition of the harvested fish was significantly different between fish fed higher and lower protein diet, except moisture. Protein and ash composition was higher for fish fed higher protein diet than that fed lower protein diet (P<0.05), however, fat composition was higher for the fish fed lower protein diet than for that fed higher protein diet (P<0.05). The fish fed higher protein diet consumed less feed but more protein (P<0.05); however, feed and protein efficiency as well as protein retention were not different between the two fish groups (P>0.05). Weight gain was higher for fish fed lower protein diet but protein gain was higher for fish fed higher protein diet (P>0.05).