An 8-week study was conducted to evaluate the effects of dietary marine protein hydrolysates as fish meal replacers in low-fish diets on the growth performance, feed utilization, and health status of Asian seabass (Lates calcarifer). The high fish meal (HFM) diet contained 25% fish meal, while the low fish meal (LFM) diet replaced 60% of the fish meal with soybean meal. Three experimental diets were formulated by supplementing the LFM diet with 5% tuna hydrolysate (TH), 2% shrimp hydrolysate (SH), and 5% salmon silage (SS), each replacing an equivalent amount of fish meal. These diets were designated as LFM+TH, LFM+SH, and LFM+SS, respectively. The results showed that the LFM+TH diet significantly improved percent weight gain, average daily growth, specific growth rate, protein efficiency ratio, and feed conversion ratio compared to the LFM diet (P 0.05), without negatively affecting feed intake or metabolic markers. Histological analysis revealed improved villus length and goblet cell count in the intestine, indicating better nutrient absorption (P 0.05). However, no significant differences were observed in hematological and immunological parameters, blood plasma metabolic markers, or carcass proximate composition (P0.05). Furthermore, the LFM+TH diet exhibited superior survival rates under ammonia stress, highlighting its potential to enhance stress tolerance. These findings suggest that marine protein hydrolysates, particularly 5%TH, can serve as a sustainable and efficient alternative to fish meal protein in diets with up to 60% with soybean meal compensation, promoting better growth and survival in Asian seabass.
Poonnual et al. (Tue,) studied this question.