Influence of probiotic administration by feed or water on growth parameters of broilers reared on medicated and nonmedicated diets

Two separate performance trials were conducted to determine the effects of postpelleting feed or drinking water application of a Lactobacillus-based probiotic, alone or in combination with a phytogenic product, on growth parameters of broilers fed medicated or nonmedicated diets. Trial 1 consisted of 1,000 straight-run broilers that were randomized, placed in floor rearing pens, and fed medicated diets. At the conclusion of the experiment, BW of broilers receiving the probiotic were not different (P > 0.05) when compared with control broilers. In trial 2, stocking densities were increased to simulate local industry rearing practices, resulting in a total placement of 1,880 chicks in the same rearing facility. Broilers in trial 2 were fed nonmedicated diets. Broilers administered the probiotic by intermittent drinking water application had increased (P < 0.05) BW and improved FCR (P < 0.05) through d 40 compared with control birds. Similarly, broilers receiving the phytogenic product had reduced (P < 0.05) FCR at d 40 compared with control broilers. We conclude that probiotic administration, alone or in combination with a phytogenic product, has the potential to influence broiler performance during commercial grow-out.