Effects of Free-range access on Poultry Health
“Poultry production over the years has been very efficient,” said Anthony Pescatore, Ph.D., extension professor in the Department of Animal and Food Sciences at the University of Kentucky. While some of poultry efficiency can be attributed to genetics and improvements in nutrition, bringing birds inside also improved production. “We were able to control their environment, and we were able to protect the animal,” Pescatore said.
However, with the separation between farming and the general public continuously growing, there is an increased interest from consumers to better understand where their food comes from — hence the increased interest in free-range poultry production, he explained. Pescatore and his associates took an in-depth look at free-range access and whether or not it has an impact on animal welfare.
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| How free range access affects Poultry health |
Understanding what animal welfare means
Consumers want the best for birds and, therefore, animal welfare has been a popular topic among producers. “Many [consumers] perceive improved welfare with free-range production systems,” Pescatore said. Consumers often feel that if the birds are out on pasture or given outdoor access, then the birds' welfare is improved, he explained. Some businesses have even changed their animal welfare standards to include free range.
“What we really need to understand is what welfare means,” said Pescatore.
However, research suggests that animal welfare is very complicated, offers conflicting information and is very controversial. Europe has developed computer models that look at different factors of animal welfare for laying hens. The same has not been developed for meat birds.
Health, an important part of animal welfare
Health is important when considering animal welfare. “Typically, there is higher mortality with free-range production,” Pescatore said. The mortality range is anywhere from 0 to almost 70 percent, with the average being 10 percent.
Hens with outdoor access had lower plumage damage and a reduced incidence of footpad dermatitis compared to cage hens. Structural bone integrity was better, too. Free-range hens do have better bone integrity; however, that improved integrity is not enough to prevent fractures or keel-bone deformities, Pescatore explained.
“As the birds have more access to move, they have more chance of flying, running into things and flying higher,” he said. These are all issues that can attribute to bone issues.
Physiological measures
Physiological measures were also studied for the context of Pescatore and associates' paper. These include changes in heart rate, body temperature, respiratory rate, adrenal secretions and/or depressed immune function, which are classic measures of stress. “With these, there is no constant or consistent way of measuring animal welfare in the housing systems,” Pescatore said.
Other measures of stress include increased corticosterone levels in blood, circulating quantity of white blood cells and the ratio of specific cells, particularly the heterophil to lymphocyte (H/L) ratio. “Higher H/L ratios have been found in hens raised in cages compared to free range,” he said. However, results do depend on different variables, including how the samples were taken and the handling of the birds, he noted.
Birds' needs and wants
“When the birds are indoors in cages, we are meeting the birds' physical needs. When we try to meet their required behavioral needs, we start having a balance,” Pescatore said. Stress is usually brought onto birds through either aversion or deprivation. Aversion is stress resulting from conditions that an animal wants to avoid. Deprivation is stress resulting when an animal is unable to complete a behavior that it wants to do. Preference tests have been utilized to study stress in birds. These tests have been used in controlled situations to determine needs and wants; however, the findings have not consistently transferred to the farm, he explained.
When results from the preference tests were applied to on-farm settings, there were no consistent results that showed a positive result for the birds.
Fear in birds
“The way we measure fear in birds is called tonic immobility,” Pescatore said. Tonic immobility is when a bird is placed on its back, and the time it takes for the bird to flip over is measured. The longer it takes for the bird to flip over, the more fearful the bird is.
“Laying hens on range showed that the hens that spent most of the time outside displayed a decrease in fearfulness as indicated by reduced time of tonic immobility,” he explained. Hens that spent less time outside indicated higher levels of fearfulness during the tonic immobility test.