Menu

The Science Behind the Better Chicken Commitment

The Better Chicken Commitment is informed by over 150 independent scientific studies published in academic journals.

A chicken

How were the welfare standards in the Better Chicken Commitment developed?

The Better Chicken Commitment is informed by over 150 independent scientific studies published in academic journals, including Animals, Poultry Science, Animal Behavior, and The Veterinary Journal.

This body of research covers each of the Better Chicken Commitment components (litter, lighting, stocking density, environmental enrichments, slaughter, and breed) and the wide range of welfare outcomes they influence (including walking ability, activity level, capacity to express natural behavior, presence of skin lesions and muscular myopathies, and mortality).

More information can be found in the complete EU Broiler Chicken Welfare White Paper.

Breed

  • The genetic selection of broilers has led to a 400% increase in broiler growth rate, achieving market weight in 60% less time than broilers 50 years ago.[1]
  • Faster growing broilers at 30 kg/m2 and with environmental enrichment have consistently higher gait scores, worse feather cover, are less reactive, have lower perch use, higher mortality and cull rates, and more downgraded meat, compared to slower growing birds under the same conditions.[2]
  • Conventional breeds have a significantly higher incidence of visible muscular myopathies, such as white striping and wooden breast, which lower meat quality. These conditions are significantly lower in slower growing breeds.[3]
  • Faster growing breeds require around 3 to 9 times more antibiotics than slower growing breeds.[4] [5] [6]

Environment

  • Studies have shown that higher stocking densities decrease locomotor activity, stretching behaviour, walking, eating, preening, and shaking.[7] [8]
  • Even slower growing breeds housed at higher stocking densities have poorer walking ability (as measured via the gait score), higher prevalence of contact dermatitis and worse litter quality than when housed at lower stocking densities.[9]
  • Relative humidity significantly increases above 30kg/m2, increasing the risk of heat stress.[10]
  • Providing natural light is extremely important as it reduces the percentage of time that broilers spend lying and improves leg health.[11]

Slaughter

  • The birds’ legs are compressed during shackling, causing pain.[12]
  • Live inversion increases the levels of stress that poultry are subjected to during the shackling process.[13]
  • Pre-stun electric shocks that do not kill the bird can occur if the birds’ wings make contact with the water-bath before their heads do,[14] [15] [16] leading to birds still being alive through the neck cutting stage.
  • Controlled atmosphere stunning eliminates the need for live handling, shackling, and inversion of conscious chickens and should ensure chickens are fully unconscious at neck cutting and dead by the time they reach the scalding tank.[17] [18] [19] [20]

More information on the science behind the Better Chicken Commitment can be found in the EU Broiler Chicken Welfare White Paper, which offers a deep dive into the science supporting the Better Chicken Commitment.

  1. Zuidhof, M. J., Schneider, B. L., Carney, V. L., Korver, D. R. & Robinson, F. E. Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005. Poultry Science 93, 2970–2982 (2014). ↩︎

  2. Baxter, Mary, Anne Richmond, Ursula Lavery, and Niamh E. O’Connell. 2021. “A Comparison of Fast Growing Broiler Chickens with a Slower-Growing Breed Type Reared on Higher Welfare Commercial Farms.” PloS One 16 (11): e0259333. ↩︎

  3. Dixon, Laura M. 2020. “Slow and Steady Wins the Race: The Behaviour and Welfare of Commercial Faster Growing Broiler Breeds Compared to a Commercial Slower Growing Breed.” PloS One 15 (4): e0231006. ↩︎

  4. Netherlands Veterinary Medicines Institute (SDa). Usage of Antibiotics in Agricultural Livestock in the Netherlands in 2022. https://cdn.i-pulse.nl/autoriteitdiergeneesmiddelen/userfiles/EN/SDa-rapporten/engels-def-sda-rapport-met-brief---het-gebruik-van-antibiotica-bij-landbouwhuisdieren-in-2022-revision.pdf (2023). ↩︎

  5. European Medicines Agency. Categorisation of antibiotics used in animals promotes responsible use to protect public and animal health. https://www.ema.europa.eu/en/news/categorisation-antibiotics-used-animals-promotes-responsible-use-protect-public-and-animal-health (2020). ↩︎

  6. AVINED. Antibioticumgebruik Pluimveesector in 2021 en de trends van de afgelopen jaren. Preprint at https://www.avined.nl/wp-content/uploads/2022-091-E0002-Infographic-2021-V006.pdf (2022). ↩︎

  7. Zhao, F., Zhao, Y., Geng, A., Shi, Z. & Li, B. Effects of stocking density on behavior of broilers in cage system. in Proceedings of the VIII Livestock Environment Symposium (2008). doi:10.13031/2013.25553. ↩︎

  8. Dawkins, M. S., Donnelly, C. A. & Jones, T. A. Chicken welfare is influenced more by housing conditions than by stocking density. Nature 427, 342–344 (2004). ↩︎

  9. Eijk, Jerine A. J. van der, Jan van Harn, Henk Gunnink, Stephanie Melis, Johan W. van Riel, and Ingrid C. de Jong. 2023. “Fast- and Slower-Growing Broilers Respond Similarly to a Reduction in Stocking Density with Regard to Gait, Hock Burn, Skin Lesions, Cleanliness, and Performance.” Poultry Science 102 (5): 102603. ↩︎

  10. Jones, T. A., C. A. Donnelly, and M. Stamp Dawkins. 2005. “Environmental and Management Factors Affecting the Welfare of Chickens on Commercial Farms in the United Kingdom and Denmark Stocked at Five Densities.” Poultry Science 84 (8): 1155–65. ↩︎

  11. Bailie, C. L., Ball, M. E. E. & O’Connell, N. E. Influence of the provision of natural light and straw bales on activity levels and leg health in commercial broiler chickens. Animal 7, 618–626 (2013). ↩︎

  12. Gentle, M. J. & Tilston, V. L. Nociceptors in the legs of poultry: Implications for potential pain in pre-slaughter shackling. Animal Welfare 9, 227–236 (2000). ↩︎

  13. Bedanova, I. et al. Stress in broilers resulting from shackling. Poultry Science 86, 1065–1069 (2007). ↩︎

  14. Raj, M. Welfare during stunning and slaughter of poultry. Poultry Science 77, 1815–1819 (1998). ↩︎

  15. Shields, S. J. & Raj, A. B. M. A critical review of electrical water-bath stun systems for poultry slaughter and recent developments in alternative technologies. Journal of Applied Animal Welfare Science 13, 281–299 (2010). ↩︎

  16. Berg, C. & Raj, M. A review of different stunning methods for poultry—animal welfare aspects (stunning methods for poultry). Animals 5, 1207–1219 (2015). ↩︎

  17. Shields, S. J. & Raj, A. B. M. A critical review of electrical water-bath stun systems for poultry slaughter and recent developments in alternative technologies. Journal of Applied Animal Welfare Science 13, 281–299 (2010). ↩︎

  18. Berg, C. & Raj, M. A review of different stunning methods for poultry—animal welfare aspects (stunning methods for poultry). Animals 5, 1207–1219 (2015). ↩︎

  19. Raj, M. & Tsemeni-Gousi, A. Stunning methods for poultry. World’s Poultry Science Journal 56, 291–304 (1996). ↩︎

  20. Devos, G., Moons, C. P. H. & Houf, K. Diversity, not uniformity: slaughter and electrical waterbath stunning procedures in Belgian slaughterhouses. Poultry Science 97, 3369–3379 (2018). ↩︎

Today we're excited to announce that we've signed up to the Better Chicken Commitment. Chicken is our business and we have a responsibility to support change.

KFC UK