Broiler growth rate contributes to behavioral differences and sheds light on the impact on welfare

Poultry companies weigh costs and efficiency on higher animal welfare standards, a study comparing traditional, growing broiler varieties has shown that slow-growing chickens exhibit behaviors more closely related to positive welfare.

Chickens, specially raised for meat production, are usually grown for 6-8 weeks, but must grow up for up to 12 weeks to mature.

Though popular in some European markets, slow-growing broilers have not seen the same market expansion in the US, as they take longer to reach the market weight than traditional broilers.

“The economic impact on the broiler industry raises the question, “Why would you want to use broilers that cost more food, grow slowly and produce?”

Whittle, alongside Shauna Weimer, an assistant professor of poultry science and director of the Center for Food Animal Welfare, set out to explore this question facing industry leaders looking to select traditional broilers and slowly growing broilers.

Weimer is researching the Arkansas Agricultural Experiment Station, part of the University of Arkansas Agricultural Bureau. Food Animal Welfare Centres are units in the agricultural sector.

Their study investigated a comparison of the physiological age and physiological age of two genetic strains in genetic strains, inventory density and most importantly, broiler behavior. A genetic strain, or a particular type of chicken, defines whether the broiler is conventional or slowly growing. Inventory density represents the number of birds in a particular area.

Researchers reviewed bird video recordings at designated intervals to track behaviors such as walking, standing and writing, which are indications of aggressive animal welfare. Planting is when a bird uses its beak to clean its wings.

Their study, “Broiler Behaviors of Genetic Strains, Cultivation Density, and Age,” was published in Poultry Science.

The results of this study revealed that it was observed that more traditional broilers were sitting in a lateral position, while a larger proportion of slowly growing broilers were standing. The impact of inventory density was minimal, so the number of birds in the area had no significant impact on broiler behavior.

Details of bird behavior

Weimer pointed out that “animal welfare is very dynamic,” and emphasized that further investigation of broiler behavior should be carried out. Whittle also emphasized that their research focuses on understanding the impact of growth rates on broiler behavior. It’s not necessarily the best for businesses and consumers.

Whittle also said that the study focuses on two broilers, but that “every genetics company has different chicken recipes.” Therefore, it is important to recognize the possibility that “one genetic strain in a broiler behaves completely differently from the other genetic strain.”

Whittle said further research is needed because “it’s always important to expand, so it’s not just generalizing based on two specific genotypes.”

Co-authors of this work include Darrin Karcher and Marisa Erasmus, associate professors of animal science at Purdue University. Animal care staff from Purdue University’s Poultry Corps, Olivia Walton, Heidi Linehart and Nathan Griffiths, also contributed to the work.