Embryo viability and hatchability under eggshell-free culture in White Leghorn and Barred Plymouth Rock chickens

Eggshell-free (ex ovo) culture systems enable direct observation and manipulation of avian embryos, but embryo viability and hatchability under these conditions remain variable. This Research Note evaluated embryo viability during culture and hatchability of White Leghorn (WL) and Barred Plymouth Rock (BPR) chicken embryos under eggshell-free culture. A total of 28 embryos from two independent experiments were analyzed (WL, n = 13; BPR, n = 15). Embryo viability during culture was analyzed using the Kaplan-Meier method, with embryo death or developmental arrest treated as an event and hatching treated as a censored observation at the day of hatching. Embryo viability during culture did not differ significantly between WL and BPR embryos by the log-rank test (p = 0.472). Hatching was observed in 3 of 15 BPR embryos (20.0%; 95% CI, 4.3-48.1%) but in none of the 13 WL embryos (0.0%; 95% CI, 0.0-24.7%); however, hatchability did not differ significantly between breeds by Fisher's exact test (p = 0.226). All 3 hatched chicks died from undetermined causes within 2 wk. after hatching; these post-hatching observations were treated descriptively and were not included as primary endpoints. These results support the separate assessment of embryo viability during culture and hatchability under eggshell-free culture conditions. Although statistically significant breed differences were not detected in the present dataset, the observation that hatching occurred only in BPR embryos highlights the need to consider breed, genetic background, or source-flock-related factors as potential contributors in future evaluations of eggshell-free culture systems.