Goldstrip sardine (Sardinella gibossa) and poultry by-product protein hydrolysate effects on amino acid composition, growth and alevines survival of rainbow trout (Oncorhynchus mykiss)

Effects of Goldstrip sardine (Sardinella gibossa) and poultry by-product protein hydrolysate on amino acid composition, growth and alevines survival of rainbow trout (Oncorhynchus mykiss) were investigated. Two hydrolyzed protein sources were incorporated into six diets for start-feeding rainbow trout (Oncorhynchus mykiss) alevines, in 3 different replacing levels (10%, 25% and 50%) of fish meal. Goldstrip sardine protein hydrolysate (SPH) and poultry by-product protein hydrolysate (PPH) were used, respectively. To compare the results, we used the same diet without protein hydrolysate. The diet with 25% SPH and 10% PPH offered the best results in terms of growth, survival, protein efficiency ratio, protein productive value and condition factor. Alevines fed with 25% SPH and 10% PPH showed more balanced amino acid composition in their body. By enhancing the protein hydrolysate in the diet, free amino acid composition in the diet and fish body was enhanced. The protein hydrolysate enhancement showed negative correlation with growth factors. Also, non essential amino acid composition of the body composition showed positive correlation with the lipid/protein percentage of the alevines. We conclude that an optimum level of protein hydrolysate can improve growth and performance of the rainbow trout alevines. However, excess protein hydrolysate can cause imbalanced amino acid composition in fish body and reduces the growth and survival factors. Based on this study, the optimum replacement of fish meal by SPH and PPH in rainbow trout alevines’s diet is 25% and 10%, respectively.