Short periods of incubation during egg storage increase hatchability and chick quality in long-stored broiler eggs

It is recognized that cool egg storage for 8 d or longer, commonly employed in broiler parent and commercial layer production, reduces hatchability. In this study, we investigated the efficacy of short periods of incubation during egg storage (SPIDES) in the restoration of hatchability of broiler hatching eggs stored for 21 d. Prolonged cool storage reduced hatchability of untreated eggs from 92 to 71%. The SPIDES treatment, which consisted of four 4-h preincubations at 4- to 5-d intervals during storage, reduced the incubation time and restored hatchability to 84% by lowering both early and late embryo mortality (P = 0.0002). The SPIDES-treated embryos exhibited higher proportions of viable cells after each preincubation (P = 0.02), potentially alleviating the negative effects of storage-induced cell death on embryo development. After completion of 4 preincubations, SPIDES embryos were advanced to intermediate primitive streak formation, a developmental stage previously associated with embryo mortality during storage. In contrast to reported preincubation methods imposed on-farm immediately before the eggs are first cooled, the SPIDES technique permits 4 d of cool storage before the initial preincubation treatment, introducing flexibility in the incubation protocol and enabling cool storage up to 3 wk with much improved hatch rates than would usually be expected. Although SPIDES chicks exhibited a BW equivalent to that of embryos derived from unstored eggs at hatch, the initial relative growth was increased as a result of SPIDES, generating a higher BW over the first 4 wk posthatch (P < 0.05). Single preincubations of 6 and 12 h at 4 d of storage caused similar advances in embryo stage to the SPIDES treatment, but the hatchability was worse than in the untreated controls, suggesting small multiple preincubations during storage have a greater benefit than a single incubation performed on d 4 of storage. Future research regarding the cellular and molecular basis of physiological stress reduction in SPIDES embryos will yield new insights into the alleviation of early embryo mortality associated with egg storage.