Effects of different levels of macroalga Gracilaria lemaneiformis on growth performance and feed utilization on the red sea bream, Pagrosomus major

摘要

In the present study, diets prepared to contain 0% (D0), 3% (D3), 6% (D6), 9% (D9), 12% (D12), and 15% (D15) of the red alga Gracilaria lemaneiformis were used to investigate the effects of G. lemaneiformis on the growth, carcass composition, and activities of enzymes related to nutritional metabolism of juvenile red sea bream (Pagrosomus major). The weight gain (WG), specific growth rate (SGR), apparent digestibility coefficients (ADC), feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) were significantly higher in D3 than in the other treatment groups (P < 0.05). Although the feed intake (FI) of D15 was greatly higher than that of the D0, the ADC of crude lipid, hepatic lipid level, and hepatosomatic index (HSI) of D15 (P > 0.05) were significantly reduced. Compared to the D0, hepatic glycogen and serum aspartate aminotransferase (AST) activity in the liver as well as serum total cholesterol (TC) of the fish on D3 and D6 were significantly higher (P < 0.05). Significantly higher activity of lipoprotein lipase (LPL) in the abdominal adipose tissues of fish fed on D3 was also observed (P < 0.05). The activities of lipase in anterior intestines appear decreased when the G. lemaneiformis supplementation level was over 12%. These results indicate that incorporate 3% G. lemaneiformis in diet could improve the growth performance and feed utilization of juvenile red sea bream. Incorporation of G. lemaneiformis at 15% level in the diet was also feasible for juvenile red sea bream, as it had no influence on growth performance.