EFFECTS OF REPLACING ANIMAL MEAL WITH DIFFERENT ADVANCED SOY PRODUCT AND CORN PROTEIN CONCENTRATE ON THE GROWTH AND DISTAL INTESTINE HISTOLOGY OF FLORIDA POMPANO Trachinotus carolinus

The present study was designed to evaluate the utilization of porcine meal in combination with advanced soy products (enzyme-treated soy and fermented soy) or corn protein concentrate (CPC) to improve the nutritional quality of plant-based diet on growth performance, body composition and distal intestine histology of Florida pompano Trachinotus carolinus. Four experimental diets were formulated to be iso-nitrogenous and iso-lipidic basis, to contain 40% crude protein and 8% lipid. A reference diet (PBMD) contained 150 g kg^-1 poultry by-product meal (PBM) and 495 g kg^-1 soybean meal (SBM), and three test diets were formulated replacing PBM with 15 g kg^-1 of CPC (CPCD) and replacing all SBM and PBM with 535 g kg^-1 fermented soy (FSBMD) and 451.3 g kg^-1 enzyme-treated soy (ESBMD). All test diets were supplemented with porcine meal (PM, 38 g kg^-1 of the diet) to serve as a hydroxyproline source. Diets were fed to apparent satiation to triplicate groups of Florida pompano juveniles (mean weight 8.06 ± 0.22 g). After 8 weeks of feeding, fish fed CPCD and ESBMD performed equally well in terms of final body weight, thermal growth coefficient and percentage weight gain in comparison to fish fed PBMD (P<0.05). Voluntary feed intake (VFI) of fish fed FSBMD was significantly lower compared to other treatments. No significant differences were observed in protein, fat, ash, phosphorus, sulfur, potassium, magnesium, calcium, sodium, and zinc contents of whole pompano body across all the treatments. The results obtained in the present histological study showed no significant differences in the thickness of serous layer, muscular layer, and submucous layer among treatments. Fish fed CPCD showed a significant widening of LP with an increase of cellular infiltration and higher presence of goblet cells compared to other dietary treatment, while no significant difference in these histological features between fish fed PBMD, CPCD and ESBMD.  Based on these results, PM in combination with 451 g kg^-1 enzyme-treated soy or 150 g kg^-1 of CPC and SBM can totally replace PBM in the practical diets without any adverse effects on growth, nutritive parameters and several distal intestine health parameters of juvenile Florida pompano.

Keywords: Enzyme-treated soy, fermented soy, porcine meal, corn protein, growth, distal intestine, Florida pompano