Flock social dynamics play an underrated yet influential role in broiler breeder reproductive performance

A research team led by Charlene Hanlon, PhD, at Auburn University demonstrated the importance of flock social dynamics, such as group size, on broiler breeder reproductive performance.

Declining fertility and hatchability remain significant challenges in commercial broiler breeder flocks, particularly as birds age. Although previous research has focused primarily on semen quality, reproductive hormones and egg quality, this project examined how flock social dynamics influence reproductive performance.

The researchers evaluated the effects of group size, mating system, male spiking and bodyweight variation to identify management strategies that could improve egg production, fertility, hatchability and overall chick output while maintaining flock uniformity and reproductive efficiency.

Influence of social factors

The study found that group size was one of the most influential factors affecting reproductive performance. Hens housed in small groups produced approximately 25 more eggs and 27 more settable eggs per hen than those housed in large groups. However, fertility was consistently higher in large groups, even though small groups exhibited greater mating activity, improved sperm viability and higher sperm penetration.

“These findings suggest that fertility is influenced by more than sperm availability alone and that social interactions and mating efficiency play critical roles in reproductive success,” Hanlon said.

Although fertility was lower in small groups, their increased egg production largely compensated for these losses, resulting in comparable chick output per hen housed.

Additionally, no single male or female reproductive trait consistently explained age-related declines in fertility. Instead, social dynamics appeared to exert a greater influence on female reproductive performance. This was shown by the substantial reduction in cumulative egg production observed in large groups while most male reproductive characteristics remained unchanged.

Furthermore, the researchers observed no differences in egg production or reproductive development between artificially inseminated and naturally mated hens, indicating that neither male presence nor mating activity alone accounted for reduced production.

“These results suggest that the broader social environment plays a more important role in reproductive performance than previously recognized,” Hanson noted.

Male spiking increased mating activity, testosterone concentrations and sperm penetration, although fertility improvements varied by flock structure. Bodyweight variation also affected reproductive organ development, with heavier males developing larger testes and heavier females exhibiting larger ovaries and greater abdominal fat reserves despite no measurable hormonal differences.

These findings underscore the importance of maintaining flock uniformity throughout production to minimize variation in reproductive performance.

Summary

“Overall, this project demonstrates that flock social dynamics are an important and often overlooked determinant of reproductive success in broiler breeder operations,” Hanlon said.

Traditional measures of reproductive capacity were frequently poor predictors of fertility, highlighting the need to better understand how social interactions influence reproductive efficiency. The results provide valuable insights that can help optimize breeder management practices and improve egg production, fertility, hatchability and overall chick output in commercial poultry production.

The research was funded by USPOULTRY and the USPOULTRY Foundation. Click here to view the industry summary.

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