Evaluating fermented soy pulp as feed supplement on the growth and health performances of African catfish, Clarias gariepinus.

The increased demand for fish feed pellets from the global aquaculture sector has made the quality of fermented soy pulp (FSP) used as the pellets’ coating material even more significant. The coating technique was employed in this study to assess the physical, biochemical, and bacteriological properties of FSP-coated experimental diets and to evaluate the loading potency of probiotics on fish feed pellets for the growth performance and health status of African catfish Clarias gariepinus. FSP was designated as a model edible coating material on fish feed pellets (0%, 25%, 50% and 75%) to deliver the probiotics to the fish gut. Lactobacillus spp. were employed as a model probiotic and model bacteria for the demonstration of this study in African catfish production. This resulted in the experimental diets showing significant differences (p < 0.05) in their FSP’s physical properties. The feed colour was more yellowish black and its odour was stronger with increasing levels of FSP coating on the fish feed pellets. Experimental diets with higher levels of FSP coating produced a mean value of lactic acid bacteria (LAB) that was significantly (p<0.05) higher. The experimental diets had similar trends in palatability. The fish consumed less than 100% of the feed provided in the 0%, 25% and 50% FSP diet groups in 5 min, while the 75% FSP diet group showed that the fish ate under 50% of the feed provided in 5 min. On the whole, the experimental diets had significantly different (p < 0.05) growth parameters where the 50% FSP diet showed the most weight gain and SGR with mean and standard deviation of 1552.41±81.67 % and 1.73±0.03 % respectively. The haematology showed that the mean values of Red Blood Cell (RBC) and Lymphocytosis (LYM) were significantly highest (p < 0.05) in the 50% FSP diet compared with the other diets. Blood biochemicals showed that there were no specific trends among the different feeds tested. FSP as a protein supplement of the experimental diets had a significant effect (p < 0.05) on villus length, width and crypt depth in the anterior and posterior gut of fish. The histological study of the intestinal revealed that the gut of the 50% of FSP coated fish feed diets had an intact epithelial barrier with goblet cells arrangement and very well-organised villus structure, tunica muscularis compared with the other groups of fish feed treatments. Besides that, the liver cells of the 50% of FSP fish feed diet had a better nuclei and cytoplasm structure compared with the other groups. Relative protein digestibility (RPD), amylase and lipase and gene expression (TGF-β1, lyzg, NF-kβ and hsp90a) were significantly highest (p < 0.05) in the 50% FSP diet. Fresh insights have been demonstrated by the findings of the study into the production of plant-based FSP coating products. These insights would efficiently enhance the generation of aqua feed which are low in cost and healthy towards the production of African catfish and other species of freshwater fish. Thus, a new theory on using FSP as a plant-based coating material as well as a protein supplement for fish growth and health status booster may be achieved at 50% FSP coated diet.