ABSTRACT

1. Sex-specific variations in early embryonic development rates may pre-empt later variations in embryonic development through to pipping and hatching. Given that erythropoiesis (blood production) can be equated with early embryonic growth rate, it was hypothesised that blood pigment haemoglobin can act as a specific spectral fingerprint for changes in growth rate. Moreover, by measuring longitudinal, rather than lateral, spectral transmission through the egg, a more consistent spectrum with a higher signal-to-noise ratio could be captured.

2. Longitudinal visible transmission (T575/T598 ratio), which is sensitive to haemoglobin, was used to monitor sex-specific early embryonic development rate in white layer chicken eggs from d 0 to 8 of incubation. The sex of these eggs was subsequently confirmed two days after hatching.

3. Embryonic development was detectable from d 3 (72 h) of incubation, 36 h earlier than previously reported lateral spectral measurements, supporting the greater sensitivity of longitudinal measurements.

4. At d 3, the mean T575/T598 ratio for male embryos was significantly lower (P < 0.001) (i.e. higher absorbance of haemoglobin) than for female embryos, which was thought to be due to sex-differences in early embryogenesis. On the other hand, female embryos had a significantly lower (P < 0.05) mean T575/T598 ratio than male embryos at d 7 of incubation, presumably due to the combined effects of oestrogen synthesis receptors and enzymes on erythropoiesis in female embryos at this time.

5. In conclusion, the proposed methodology has the sensitivity to differentiate sex-specific embryonic development rates during early incubation and the potentiality to advance precision incubation management and poultry research.

摘要

1.早期胚胎发育速率的特定性别差异可能会阻止后来的胚胎发育变异直至抽水和孵化。鉴于红细胞生成（血液生成）可以等同于早期胚胎的生长速率，因此可以假设血色素血红蛋白可以作为生长速率变化的特定光谱指纹。此外，通过测量通过鸡蛋的纵向而不是横向的光谱传输，可以捕获具有更高信噪比的更一致的光谱。

2.对血红蛋白敏感的纵向可见光透射率（T575 / T598比）用于监测孵化后第0到8天白蛋鸡的性别特异性早期胚胎发育速率。孵化两天后证实了这些卵的性别。

3.孵育第3天（72 h）可检测到胚胎发育，比以前报道的横向光谱测量早36 h，从而支持了纵向测量的更高灵敏度。

4.在第3天，男性胚胎的平均T575 / T598比明显低于女性胚胎（P <0.001）（即血红蛋白的吸收），这被认为是由于早期胚胎发生中的性别差异引起的。另一方面，在孵化第7天时，雌性胚胎的平均T575 / T598比率显着低于雄性胚胎（P <0.05），这可能是由于此时雌激素合成受体和酶对红细胞生成的综合作用。

5.总之，所提出的方法具有区分早期孵化过程中性别特异性胚胎发育速率的敏感性，并具有促进精确孵化管理和家禽研究的潜力。