Supplementation of Postbiotic RI11 Improves Antioxidant Enzymes Activity, Upregulated Gut Barrier Genes and Reduced Cytokines, Acute Phase Proteins and HSP70 Gene Expression Levels in Heat-Stressed Broilers
Authors: Humam Ali Merzza , Loh Teck Chwen , Foo Hooi Ling , Izuddin Wan Ibrahim , Zulkifli Idrus , Samsudin Anjas Asmara , Mustapha Noordin Mohamed 
Published: April 2020

Abstract
Background

To alleviate the adverse impacts of stressful environmental conditions on poultry and promoting the animal's health and growth performance, antibiotics have been added to poultry diets as growth promoters. Nevertheless, improper and overuse of antibiotics as feed additives have resulted the emergence of antibiotic-resistant bacteria and increased the levels of antibiotic residues in animal products, which have disastrous effects on the health of both animals and humans. Postbiotics produced from probiotic Lactobacillus plantarum have been the recent research of interest as dietary additives for livestock and potential alternatives to antibiotics. However, there is very scarce of study has considered the effect of postbiotics on broilers under heat stress. The aim of this work was to evaluate the impacts of feeding different levels of postbiotic RI11 on antioxidant enzyme activity, physiological stress indicators, cytokines and gut barrier genes expression in broilers under heat stress.
Materials and Methods

A total of 252 male Cobb 500 were fed with 1 of 7 diets: NC (negative control, 0.0% RI11) basal diet; OTC (positive control) NC + 0.02% (w/w) oxytetracycline; AA (antioxidant control) NC + 0.02% (w/w) ascorbic acid. Four further groups were NC + 0.2, 0.4, 0.6 and 0.8% postbiotic RI11 (v/w) of the respective levels.
Results

Supplementation of different levels of postbiotic RI11 increased plasma glutathione peroxidase, catalase and glutathione enzymes activity. Postbiotic RI11 groups upregulated the mRNA expression of interleukin 10 and downregulated of interleukin 8, tumor necrosis factor-alpha, heat shock protein 70 and alpha 1- acid glycoprotein levels compared to the NC and OTC groups. Feeding various doges of postbiotic RI11 improved the integrity of the intestinal barrier by the upregulation of zonula occludens-1 and mucin2 mRNA expressions. However, no difference was observed in claudin1, ceruloplasmin, interleukin 6, interleukin 2 and interferon expression, but downregulation for occludin expression as compared with the NC group. Supplementation of postbiotic RI11 in different levels quadratically increased the plasma glutathione peroxidase, catalase and glutathione, interleukin 10, mucin2 and zonula occludens-1 mRNA expression, and reduced plasma interleukin 8, tumor necrosis factor-alpha, alpha 1- acid glycoprotein and heat shock protein 70 mRNA expression. Supplementation of postbiotic RI11 at level 0.6% was sufficient to achieve the improvement in health of broiler chickens under heat stress as compared to other levels.
Conclusions

The results suggested that postbiotic produced from L. plantarum RI11 particularly at level 0.6% (v/w) could be used as an alternative to antibiotics and natural sources of antioxidants in the poultry industry.