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This research was conducted to evaluate the impact of dietary or drinking water Ruminococcus sp. supplementation and/or heat stress (HS) on the growth, serum biochemistry, tissue antioxidant, phagocytic assay, histopathology, and bursa gene expression of broilers. Day-old broiler chicks were allotted into six groups according to HS and/or Ruminococcus with or without enzyme supplementation. The first group was the control one, with a formulated diet and normal environmental temperature but without any supplement. The second group fed on Ruminococcus-supplemented diet (1 kg/kg diet). The third group fed on a formulated diet without supplement, and Ruminococcus and digestive enzymes were given in drinking water (0.1 ml/L). The fourth one was the heat stress group, with a normal formulated diet. The fifth and the sixth groups served as second and third groups, respectively, but with heat stress. The results of this experiment indicated that thermal temperature negatively affected the parameters of growth performance, serum biochemical, tissue antioxidants, and phagocytic assay. Moreover, heat stress led to pathological lesions in the internal organs and affected the expression of some genes related to heat stress, including proapoptotic genes such as caspase8 and bax, inflammatory genes such as NF-κβ1, and heat shock protein such as HSP 70 in the bursal tissue. These bad effects and abnormalities were mitigated by Ruminococcus alone or with enzyme supplementation, which improved all the above-mentioned parameters.

The aim of the present study was to examine the effects of dietary inclusion of fermented poultry by-product meal (FPBM) on growth performance, digestive enzymes activity, innate immunity, and antioxidant capacity in Nile tilapia (Oreochromis niloticus). A basal diet containing fish meal and soybean meal was considered as a control (Con), and four other diets were produced by inclusion of 10, 20, 30, or 40% FPBM (FPBM10, FPBM20, FPBM30, and FPBM40 diets). The experiment was done in triplicates (20 fish per replicate) and the fish were fed the test diets to visual satiety twice daily for 8 weeks. The groups of fish fed the FPBM10 and FPBM20 diets showed significantly (P < 0.05) higher weight gain and specific growth rate, and lower feed conversion ratio than those fed the Con and FPBM40 diets. Moreover, inclusion of 40% FPBM led to significant reduction of feed intake compared to the other treatments. FPBM at all the tested levels improved intestinal protease activity and lipase activity was enhanced at 10–30% inclusion levels. Furthermore, the FPBM10 and FPBM20 groups revealed significantly higher amylase activity than the other treatments. The FPBM10 group exhibited significantly higher phagocytic activity than the control group and phagocytic index was enhanced by dietary inclusion of 10–30% FPBM. However, inclusion of over 30% FPBM led to significant reduction of lysozyme, phagocytic, and bactericidal activities compared to the control group. Further, FPBM10 and FPBM20 diets increased the serum IgM levels, while NBT was significantly increased by feeding FPBM10 diet compared with FPBM30 and FPBM40 groups (P < 0.05). The group fed the FPBM30 diet showed significantly higher glutathione peroxidase activity than the control group. According to the analysis of the data by the polynomial regression, the inclusion of FPBM at 11.17–25.14% can be applied effectively in the diets of tilapia for better growth performance and health condition.