Efficacy and Safety Assessment of Microbiological Feed Additive for Chicken Broilers in Tolerance Studies

INTRODUCTION: One aim of the study was to evaluate the impact when added to feed of the two potentially probiotic strains of lactic acid bacteria (LAB) Lactobacillus plantarum K KKP 593/p and Lactobacillus rhamnosus KKP 825 on production performance, health, and the composition of gut microbiota. The complementary aim was to assess the safety of these strains in broiler rearing. MATERIAL AND METHODS: A total of 500 one-day-old Ross 308 chicks were divided into four groups. The experimental factor was the admixture of bacterial preparation to the feed at different doses: the recommended maximum dose, a dose ten times higher, the recommended minimum dose, and a zero dose for the control group not receiving bacteria. RESULTS: Addition of bacteria to the diets did not have a significant effect on the final body weight, final body weight gain, nor total feed intake or feed conversion. However, lactic acid bacteria had a positive effect on chicken health. Mortality among chickens fed with LAB was reduced. Moreover, LAB feeding inhibited the growth of Salmonella spp. and Clostridium perfringens in the intestines. There were no significant differences in chicken performance by dose of bacteria in the feed. The group dosed with LAB ten times higher than the recommended maximum did not demonstrate changes in biochemical or haematological parameters of blood compared to the remaining groups. CONCLUSION: Feeding chicken broilers with two potentially probiotic LAB strains is safe and impacts animal health positively.