Dietary Supplementation of Postbiotics Mitigates Adverse Impacts of Heat Stress on Antioxidant Enzyme Activity, Total Antioxidant, Lipid Peroxidation, Physiological Stress Indicators, Lipid Profile and Meat Quality in Broilers

SIMPLE SUMMARY: To mitigate the adverse impacts of stressful environmental conditions on poultry and to promote the animal’s health and growth performance, antibiotics at sub-therapeutic doses have been added to poultry diets as growth promoters. Nevertheless, the improper and overuse of antibiotics as feed additives have played a major role in the emergence of antibiotic-resistant bacteria and increased levels of antibiotic residues in animal products, which have disastrous effects on the health of both animals and humans. Postbiotics, used as dietary additives for livestock, could be potential alternatives to antibiotics. Postbiotics produced from the probiotic Lactobacillus plantarum have been the subject of several recent kinds of research. However, the researchers have very rarely considered the effect of postbiotics on the broilers under heat stress. ABSTRACT: The purpose of this work was to evaluate the impacts of feeding different postbiotics on oxidative stress markers, physiological stress indicators, lipid profile and meat quality in heat-stressed broilers. A total of 252 male Cobb 500 (22-day-old) were fed with 1 of 6 diets: A basal diet without any supplementation as negative control (NC); basal diet + 0.02% oxytetracycline served as positive control (PC); basal diet + 0.02% ascorbic acid (AA); or the basal diet diet + 0.3% of RI11, RS5 or UL4 postbiotics. Postbiotics supplementation, especially RI11 increased plasma activity of total-antioxidant capacity (T-AOC), catalase (CAT) and glutathione (GSH), and decreased alpha-1-acid-glycoprotein (α1-AGP) and ceruloplasmin (CPN) compared to NC and PC groups. Meat malondialdehyde (MDA) was lower in the postbiotic groups than the NC, PC and AA groups. Plasma corticosterone, heat shock protein70 (HSP70) and high density lipoprotein (HDL) were not affected by dietary treatments. Postbiotics decreased plasma cholesterol concentration compared to other groups, and plasma triglyceride and very low density lipoprotein (VLDL) compared to the NC group. Postbiotics increased breast meat pH, and decreased shear force and lightness (L*) compared to NC and PC groups. The drip loss, cooking loss and yellowness (b*) were lower in postbiotics groups compared to other groups. In conclusion, postbiotics particularly RI11 could be used as an alternative to antibiotics and natural sources of antioxidants for heat-stressed broilers.