Efficiency of Dietary β-glucan Supplementation on Growth, Body Composition, Feed, and Nutrient Utilization in Juveniles of Pompano Fish (Trachinotus ovatus, Linnaeus, 1758)

An 8-week experiment was conducted to examine the effect of increasing levels of dietary beta-glucan on the growth performance, feed utilization, and body composition of juvenile pompano (Trachinotus ovatus). Pompano (mean initial weight, 6.45 g) were fed five diets containing five levels of beta-glucan (D1 (control): 0%; D2: 0.05%; D3: 0.10%; D4: 0.20%; and D5: 0.40%. Results showed that growth performance, body composition, efficacy of feed and nutrient utilization were significantly affected by dietary beta-glucan levels. After 8-weeks of feeding, weight gain, daily weight gain, specific growth rate, final body weight, coefficient of variation were highest in pompano fed 0.05% and 0.10% beta-glucan in the diet (P <= 0.034), while growth of fish fed 0.2% and 0.4% beta-glucan did not significantly differ compared to fish fed the control diet (P >= 0.170). Survival rate of juvenile pompano was not influenced by beta-glucan supplement in the diet (P >= 0.383). In addition, feed utilization daily feed intake, feed conversion ratio, and feed conversion efficiency were significantly lower in fish fed diets supplemented with 0.01-0.10% beta-glucan (P <= 0.027). In contrast, feeds supplemented with 0.2 to 0.4% beta-glucan did not influence the feed utilization of pompano after 56 days of diet feeding (P >= 0.051). Protein was significantly higher in the flesh of pompano fed 0.05% to 0.10% beta-glucan (P <= 0.001), while lipid content in fish decreased significantly with graded levels of beta-glucan in the diet (P <= 0.044). After 56 days, protein efficiency ratio (PER), protein productive value (PPV), and fractional rates of protein growth (K-g), were significantly higher in fish fed diets supplemented with 0.05 -0.10% beta-glucan (P <= 0.025).