Sustained in-ovo and in-feed probiotic supplementation promotes embryo development and post-hatch performance in broilers.

Current broiler production strategies largely emphasize post-hatch interventions such as feed additives and optimized housing, with limited focus on the embryonic phase. However, embryonic development and the immediate post-hatch period account for nearly half of the productive lifespan of modern broilers and play a critical role in determining market performance. This study evaluated the efficacy of probiotics in enhancing embryonic development and post-hatch performance in broiler chickens. Hatching eggs (Ross 308) were sprayed with phosphate-buffered saline (Control) or probiotics [Lactobacillus paracasei DUP 13076 (LP) and L. rhamnosus NRRL B 442 (LR)] prior to and during incubation. Embryos were sampled at defined intervals for growth and morphometric assessments. On day 18, eggs were transferred to the hatcher, and post-hatch chicks were raised for six weeks on feed with or without probiotic supplementation (∼9 log CFU/g feed). Birds were sacrificed during the grow-out phase for morphometric evaluation. Probiotic treatment significantly enhanced embryonic development as evidenced by increased relative embryo weight, crown-rump length, hatchability, and hatchling weight (p ≤ 0.05). Continued LP and LR supplementation post-hatch led to improvements in body weight gain (8-15 %), carcass weight (2.7-3.8 %), relative breast weight (4.3-4.9 %), and relative leg weight (4-4.8 %) compared to controls, without negatively affecting meat quality. Moreover, feed conversion ratio (FCR) was reduced by 3-4.9 %, with concurrent improvements in performance efficiency and survivability. These findings demonstrate that early and sustained probiotic supplementation supports robust growth and improved performance in broiler chickens. Integrating probiotics across both embryonic and post-hatch stages offers a promising strategy to enhance poultry production efficiency and bird health under commercial conditions.