Non-destructive sex-specific monitoring of early embryonic growth rate in light brown broiler eggs using light transmission and its correlation with hatching time and chick weight

ABSTRACT

1. Monitoring early embryonic growth rate (EGR) has significant economic and animal welfare benefits. This study focuses on monitoring sex-specific early EGR using light transmission, and correlating this with hatching time and chick weight. For broiler eggs in particular, spectral masking of the light brown eggshells needed to be addressed. This was done using longitudinal visible transmission spectroscopy combined with eggshell colour image analysis.

2. Prior to incubation, colour images of eggs were captured followed by daily measurements of transmission spectra of eggs from days one to nine of incubation. The sex of the eggs was subsequently verified 2 d after hatching.

3. To accurately and sensitively determine sex differences in EGR using light transmission, while minimising interference from eggshell colour and thickness, the ratio of longitudinal transmissions was determined to be most effective at 575 and 610 nm.

3. Embryonic growth was detectable from d 3 (72 h) of incubation, 24 h earlier than previously reported lateral transmission measurements. However, at this time, low blood levels meant that no significant sex-differences (P > 0.05) for the mean T575/T610 ratio were detectable. This may have been due, in part, to spectral masking from the light brown eggshells. At d 7, female embryos had a significantly lower (P < 0.05) mean T575/T610 ratio than males.

4. Although the T575/T610 ratio had low correlations with hatching time and hatch-weight of chicks, this could be a good starting point for further non-destructive investigations for such predictions.

5. In conclusion, the methodology had the sensitivity to differentiate sex-specific early EGR in broiler eggs, even with pigmented eggshells, and has the potential to advance precision hatchery management and poultry research.

KEYWORDS:

• Non-destructive
• visible transmission
• broiler embryo
• growth rate
• sex difference
• hatching time
• chick weight

Acknowledgments

The authors express their gratitude to the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Scholarship Council and Kyoto University, Japan for providing financial support, and to Mr Kunihiko Nambu, Chairman, and CEO (NABEL Co., Ltd., Japan) for giving his kind consent for this collaborative research. The authors give special thanks to Mrs Wulandari Hendi (Graduate student of Bio-Sensing Engineering Laboratory, Kyoto University, Japan) for her assistance during colour image analysis of egg samples. The authors are deeply indebted to Associate Professor Dr Garry John Piller (Graduate School of Agriculture, Kyoto University, Japan) for critically editing and proofreading this manuscript.

Disclosure statement

The authors declare that they have no conflict of interest.