In ovo probiotic supplementation enhances energy status and promotes growth in developing broiler embryos and hatchlings.

As opposed to mammals, nutrient and energy availability for the embryo is limited to the nutrients deposited in the egg. This can create an energy imbalance in the perinatal period resulting in impaired perinatal embryo development, reduced hatchability, suboptimal hatchling quality and decreased post-hatch performance. Hence, it is critical to improve the energy status of the developing embryo to support the hatchling and immediate post-hatch development. Towards this, we observed that in ovo probiotic application to broiler eggs improved hatchability and hatchling quality. To understand the underlying mechanism, we investigated the effect of in ovo probiotic supplementation on glycogen reserves and embryo development in broilers. A total of 900 eggs (Ross 308) were either sprayed with phosphate buffered saline (PBS; control) or probiotics [∼9 log CFU/egg of Lactobacillus rhamnosus NRRL B-442(LR) or Lactobacillus paracasei DUP 13076 (LP)] during incubation. On day 18, eggs were transferred to the hatcher and set up for hatching. Embryos were sacrificed for morphometric measurements on day 10, 12, 14, 16, 18, 19, 20 and 21 of incubation. In addition, yolk sac membrane (YSM), yolk sac content (YSC), breast, and liver samples were collected for glycogen analysis and gene expression assays. Overall, in ovo probiotic spray significantly increased relative embryo weight, relative breast muscle and hatching muscle (P < 0.05). Additionally, glycogen content was significantly elevated in YSM, YS, liver and breast muscle throughout incubation and in the hatchling (P < 0.05). Further, we observed a significant downregulation of genes associated with the gluconeogenic pathways including PYGL, FBP1, PEPCK-C, PEPCK-M, and GK in the YSM, liver and breast muscle at day 21 (P < 0.05), thereby sparing the need for muscle protein breakdown. This in turn indicates the availability of sufficient glycogen reserves in the perinatal embryo to fuel the hatching process. In summary, in ovo spray application of probiotics improved glycogen reserves in the embryo thereby supporting optimum embryo development and improving hatchability and hatchling quality.