Impact of dietary Lactiplantibacillus plantarum probiotics and postbiotics on gut health and immunity of layers under heat stress conditions

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This study evaluated the impact of feeding Lactiplantibacillus plantarum RS5 probiotic and its products on gut health and immune status in laying hens under heat stress. A total of 192 Isa White pullets were randomly assigned to individual cages in four environmentally controlled chambers. During the adaptation period from 1 to 21 d, all birds received the same basal diet. On d 22, the birds were divided into six treatment groups, with half in two rooms subjected to cyclic daily heat stress reaching about 30 °C and the other half allocated to two houses under regular temperature conditions. The layers were fed one of three diets: (1) Control, (2) Control + L. plantarum RS5 probiotic, or (3) Control + L. plantarum RS5 postbiotic. The feeding trial lasted for five months. The study found that heat stress negatively impacted the birds’ blood profile, with significant decreases in red blood cells, haemoglobin, haematocrit, mean corpuscular volume, platelets, mean platelet volume and plateletcrit compared to the control groups at two and five months of the trial ( P <0.05). The intestinal lesions caused by heat stress showed numeric improvements with probiotic/postbiotic supplementation, including mucosal cell degeneration and the number of villi ( P >0.05). Dietary probiotics numerically increased the humoral immune response to Newcastle Disease vaccine at 2 and 4 weeks post-vaccination ( P> 0.05), compared to the control group. In conclusion, the study showed that dietary L. plantarum probiotics and postbiotics may alleviate the impact of heat stress in the poultry industry. The findings highlighted the potential for evaluating various dietary probiotics and postbiotics in new heat stress models for layers.