LAUSR

Context Probiotics used in poultry nutrition may promote the propagation of beneficial bacteria and limit the growth of pathogens, improving the body’s resistance to disease. Aims The aim of the study was to establish the dose and timing of administration of a probiotic preparation containing live cultures of Bacillus subtilis PB6 and choline that would have the most beneficial effect on histological parameters and microbiological status of the intestine, immune status, and growth performance of broiler chickens. Methods In total, 980 one-day-old Ross 308 male chickens, divided into seven groups of 140 (each group with seven replications of 20 individuals), were used in the experiment. The birds were reared until Day 42 of life. In the control group, birds received water without addition of the probiotic preparation. In three continuous treatments, birds received the probiotic preparation in their water at doses of 0.05, 0.1 or 0.25 g/L from Day 1 to Day 42 of rearing. In three periodic treatments, birds received the same doses of the probiotic preparation, but only during Days 1–7, 15–21 and 29–35 of rearing. Key results Addition of the probiotic preparation to the drinking water of broiler chickens increased the total number of aerobic bacteria as well as the length of the intestinal villi and the depth of the crypts. It also reduced the number of fungi and coliform bacteria. In addition, increases were noted in the lysozyme content, the phagocytic index, and the level of immunoglobulin A. Conclusions The probiotic preparation containing B. subtilis and choline administered continuously at a dose of 0.25 g/L in water throughout the rearing period had the most beneficial effect on the composition of the microbiome, and improved the mucous membrane structure of the intestine (increasing villus length and intestinal crypt depth), immunity, and growth performance of the broiler chickens. Implications The use of probiotics in poultry nutrition improves the health of animals and makes breeding more profitable. Administration of this probiotic improves disease resistance, jejunal histological parameters, and intestinal microflora of broiler chickens.