Animal by-products with or without enzymatic hydrolysis completely replacement of fish meal in genetically improved farmed tilapia diets (Oreochromis niloticus)

An 8-week feeding trial was performed to examine the potential of total replacement of fish meal with animal by-products with or without enzymatic components in juvenile genetically improved farmed tilapia (GIFT) diets,Oreochromis niloticus, (mean initial weight, 19.71 +/- 0.28 g), reared in RAS system. Five isonitrogenous and isoenergetic diets were formulated with fish meal for the diets with total replacement of the isonitrogenous amounts of enzymatic fish meal (E-FM), chicken liver meal (CLM), enzymatic chicken liver meal (E-CLM), dried porcine solubles (DPS) and enzymatic dried porcine solubles (E-DPS) respectively. The results indicated that the weight gain rate (WGR) and specific growth rate (SGR) in the FM group were significantly higher than the E-FM and E-CLM groups (p< .05), but the specific growth rate (SGR) in the E-CLM group lower than the E-FM group. The feed conversion ratio (FCR) in FM and CLM was significantly lower than the E-FM, E-CLM and E-DPS groups (p < .05), and no significant difference was observed among the FM, CLM and DPS groups (p > .05). The values of the protein retention efficiency (PRE) and protein efficiency ratio (PER) in FM, CLM and DPS groups were significantly higher than the E-CLM group (p < .05). The values of feed intake ratio (FIR) in FM and CLM groups were significantly lower than the E-FM, E-CLM and E-DPS groups (p < .05). There was no significant difference in the whole body contents of moisture, crude lipid and crude ash among the FM and E-CLM groups (p > .05). The whole body contents of crude protein in the FM group were significantly higher than the E-FM, CLM, E-CLM DPS and E-DPS groups (p < .05). The apparent digestibility coefficients (ADC) of dry matter, crude protein and crude lipid in the FM, E-FM, E-CLM and E-DPS groups were not significantly different (p > .05). The serum glucose(GLU), total cholesterol (TCHO) and triglycerides (TG), or the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not affected by the different treatments (p > .05). There was no significant difference in serum total protein (TP) or albumin (ALB) and between the FM group and other groups (p > .05). There was no significant difference in the serum urea nitrogen (BUN) content in the FM, CLM, E-CLM and DPS groups (p > .05). Fish fed with the CLM and DPS diets had significantly lower hepatic GHR1, IGF1 and IGF2 gene mRNA expression levels than in fish fed the FM diet (p < .05). The present data showed that 6% of dietary fish meal can be totally replaced by the chicken liver meal and dried porcine solubles with no effect on the growth performance of GIFT strain tilapia.

Automated summary

The study found that replacing 6% of dietary fish meal with chicken liver meal and dried porcine solubles had no effect on the growth performance of GIFT strain tilapia, and even improved some indicators.