An investigation into the effects of using protein hydrolysate in low fish meal diets on growth performance, feed utilization and health status of snakehead fish (Channa striata) fingerling

Abstract

This study aimed to investigate the growth performance, feed utilization and innate immune response of snakehead fish (Channa striata) that had received a low fish meal-based diet and supplementation with protein hydrolysate. A fish meal-based diet was consider as a ‘high fish meal diet’ in feed formular (HF) and a ‘low fish meal diet’ (LF) replaced 40% of fish meal with soybean meal. Two other diets were prepared by supplementing tuna hydrolysate (TH) and poultry hydrolysate (PH) in LF diet. The experimental fish (initial mean weight 4.1 ± 0.15 g) were randomly assigned to quadruplicate group and fish were randomly distributed into 500-L circular plastic tanks at a density of 70 fish per tank. Each experimental diet was handfed three times daily to apparent satiation for eight weeks. At the terminal period, the results showed no significant difference in fish survival rates among all groups (p > 0.05), and significant improvements (p < 0.05) in percentage of weight gain and specific growth rate were obtained in fish fed dietary TH compared to among all group. In terms of feed utilization, the data showed that there was also no significant difference (p > 0.05) in feed conversion ratio (FCR) and protein efficiency ratio (PER) among all groups. Values of hematological parameters did not significantly differ among experimental groups (p > 0.05). Serum lysozyme levels increased significantly in fish fed diet TH. Other immune parameters (Catalase, MPO, SOD and RBA) were not altered by diet. However, fish fed diet TH and HF had strong fluorescence intensity, indicating slightly higher respiratory burst activity than other groups. Overall, the present findings suggest that supplementing 2.5% tuna hydrolysate in the low fish meal-based diet can improve feed intake, growth performance and innate immunity in snakehead fish.