What Is the Biology Behind Fertilization in Hens?
Most eggs sold at the grocery store will never hatch. They are unfertilized, and no rooster was ever involved in producing them. A hen ovulates and lays an egg regardless of whether a male is present. Fertilization occurs when sperm reaches the ovulated ovum in the infundibulum, the first segment of the oviduct, before albumen and shell are laid down around it (Brillard, 1993). The timing is critical: the yolk must be reached within hours of ovulation.
A distinctive feature of avian reproduction is the sperm storage tubule (SST), located at the uterovaginal junction. After mating, sperm enter these glands and remain viable for up to roughly 21 days in chickens, meaning a single mating event can yield a sequence of fertilized eggs across several weeks (Brillard, 1993; Bakst and Dymond, 2013).
How to Get Fertilized Chicken Eggs on a Small Farm
On small holdings, obtaining fertilized eggs is straightforward. A keeper introduces a mature rooster and allows natural mating. Male-to-female ratio matters: too few males reduces fertility, while too many disrupts flock order. Eggs collected in the days and weeks after successful mating will generally be fertile, provided the hen is laying actively.
How Do Chicken Eggs Get Fertilized in Commercial Production?
Commercial broiler breeder operations approach fertilization as a managed process. Male-to-female ratios, mating behavior, and individual body condition are monitored because fertility rates have a direct bearing on hatchability and production economics. The Cobb Breeder Management Guide describes the male growth profile as the single most important factor correlating with flock fertility (Cobb-Vantress, 2022). Overweight or undersized males are less able to complete successful matings, and poor fleshing scores reduce reproductive output. Some sectors, particularly turkey production in North America, use artificial insemination rather than natural mating, but in broiler chicken breeding, floor mating remains standard (Bakst and Dymond, 2013).
The Role of Weight Monitoring in Reproductive Performance
Body weight uniformity in both males and females directly influences sexual synchronization and the proportion of settable, fertile eggs produced. Hens outside the target weight range may miss peak sexual maturity, produce lower-quality eggs, or show reduced mating receptivity (Petitte et al., 1982; Robinson and Robinson, 1991). Individual bird weighing during sorting sessions lets staff compare fleshing scores against weight data and confirm that both sexes are following their target growth curves.
On farms where birds are handled individually, the BAT1 manual poultry scale is a practical tool for this purpose. Because each bird is caught and weighed separately, the resulting data reflects true individual variation rather than a population average.
Tracking weight trends between handling sessions adds a further layer of reproductive management. Continuous live weight monitoring captures population-level changes without handling, flagging gradual drift before it affects fertility outcomes. The Cobb guide recommends weekly weighing of males from one to 30 weeks of age, with immediate feed adjustments when weights deviate from standard (Cobb-Vantress, 2022).
The BAT2 Connect automatic poultry scale is designed for this type of continuous coverage, recording weights throughout the day in houses where handling every bird each week would be impractical.
Aggregating data from multiple houses and production cycles allows managers to benchmark flock reproductive performance and identify trends early. The BAT Cloud data platform draws together records from both manual and automatic weighing sessions, giving a fuller picture of where conditions may be drifting away from the requirements for consistent fertility.
References
1.) Bakst, M.R. and Dymond, J.S. (2013). Artificial insemination in poultry. In: Success in Artificial Insemination: Quality of Semen and Diagnostics Employed. InTech. https://www.intechopen.com/chapters/41721
2.) Bakst, M.R., Wishart, G.J. and Brillard, J.P. (1994). Oviductal sperm selection, transport and storage in poultry. Poultry Science Reviews, 5, 117-143. https://www.researchgate.net/publication/221962421_Oviducal_sperm_selection_transport_and_storage_in_poultry
3.) Brillard, J.P. (1993). Sperm storage and transport following natural mating and artificial insemination. Poultry Science, 72(5), 923-928. https://doi.org/10.3382/ps.0720923
4.) Cobb-Vantress (2022). Cobb Breeder Management Guide. Cobb-Vantress Inc. https://www.cobb-vantress.com/resources/management-guides/
5.) Petitte, J.N., Hawes, R.O. and Gerry, R.W. (1982). The influence of flock uniformity on the reproductive performance of broiler breeder hens housed in cages and floor pens. Poultry Science, 61(11), 2166-2171. https://doi.org/10.3382/ps.0612166
6.) Robinson, F.E. and Robinson, N.A. (1991). Reproductive performance, growth rate and body composition of broiler breeder hens differing in body weight at 21 weeks of age. Canadian Journal of Animal Science, 71(4), 1223-1231. https://doi.org/10.4141/cjas91-145