Maternal derived antibodies and avian β-defensins expression patterns and their correlation in the yolk sac tissue of different chicken breeds (Gallus gallus)

The expression of maternal derived antibodies (MDAs) and avian β-defensins (AvBDs) in yolk sac tissue may be age-specific and influenced by breed, thereby immunological window difference in hatchlings. This study investigated the mRNA expression of MDAs and AvBDs in the yolk sac tissues of Beijing You and Hy-Line Gray chickens from the embryonic day (ED)7 to 3 days after hatch (DAH). Hy-Line showed a higher embryo bodyweight and a lower residual yolk weight at ED17 (P < 0.05). The expression of IgY and FcRY was higher in the Hy-Line (P < 0.05). In Beijing You, IgA level decreased from ED15 to 19 but peaked from day old hatch to 3 DAH. In Hy-Line, IgA increased from ED19 to 3 DAH (P < 0.05). IgY increased from ED17 to day old hatch (DOH), but declined from DOH to 3 DAH in Beijing You, whereas in Hy-Line, it declined from ED9 to 15 and ED19 to 3 DAH (P < 0.05). FcRY expression declined from DOH to 3 DAH in Beijing You and from ED19 to 3 DAH in Hy-Line (P < 0.05). The expression of AvBD5 increased from ED7 to 13 and ED19 to 3 DAH, and decreased from ED13 to 19 in both breeds. A similar expression patterns of AvBD10 was observed in breeds, increased from ED7 to 11, followed by a decline after ED11. AvBD12 expression peaked at ED17 in Beijing You and from ED15 to 17 in Hy-Line (P < 0.05), then declined from ED17 to 3 DAH in both breeds. The study observed temporal expression development patterns of AvBD5 and AvBD10 in both breeds and AvBD12 in Beijing You, with a correlation coefficient of R² > 0.5. Overall, the lower yolk residue for faster growth of chickens compromised the expression of MDAs and AvBDs, except for IgA and AvBD5. These results suggest a broader immunological window and highlight the need to focus on maintaining specific MDAs and AvBDs in the strategies of embryonic feeding.