Effects of dietary Lactococcus lactis and Bacillus licheniformis on growth performance and gut health of broilers

Abstract

In this study, the effects of dietary supplementation with Lactococcus lactis and Bacillus licheni-formis on broiler performance, metabolizable energy, intestinal morphology, and ileal microflora were evaluated. A total of 300 unsexed Cobb strain broiler chickens were divided into three treatments. Treatment T1 served as the control with a basal diet plus 0.1% CaCO₃ placebo, T2 received a basal diet supplemented with 0.1% Lactococcus lactis and Bacillus licheniformis at 10⁵ CFU g⁻¹, and T3 received the same probiotic combination at 10⁶ CFU g⁻¹.
Probiotic supplementation improved growth performance, as indicated by increased body weight gain, improved feed efficiency (FCR), and higher metabolizable energy. Regarding intestinal microflo-ra, T2 reduced Escherichia coli populations, whereas T3 increased lactic acid bacteria; however, the increase in lactic acid bacteria in T3 was not accompanied by a reduction in Escherichia coli (P<0.05). Treatment T3 produced the lowest FCR value of 1.49 compared to the control (1.60) and the highest metabolizable energy of 3372 kcal kg⁻¹, indicating improved nutrient utilization efficiency.
Histological evaluation showed a tendency to increase intestinal villus height, with the highest value observed in treatment T2 (1175.39 μm), suggesting improved intestinal absorptive capacity. It was concluded that Lactococcus lactis and Bacillus licheniformis supplementation has the potential to improve performance, intestinal health, and metabolizable energy in broiler chickens, although the ef-fects on microbial populations depend on the dosage.