As recently reported by Stephanie Strom in the NY Times (Business Section, Oct. 21, 2016), hens housed in aviaries have been observed to suffer higher morbidity and mortality rates, compared to hens housed in cages. As egg farmers, veterinarians and scientists previously warned, concerns about the welfare of hens housed in aviaries results from the well-known cannibalistic behavior of hens. That behavior historically lead to the husbandry practice known as beak trimming, a practice activists consider a "mutilation."
As discussed previously, the husbandry and housing techniques used to protect of animals raised for food or fiber has developed over time, informed by animal scientists researching and testing different methods that provide for the health of the animals, their welfare, the safety of their caretakers, and to minimize negative impacts on the environment.
In "A Comparison of Cage and Non-Cage Systems for Housing Laying Hens," as reported by the AVMA, there are many factors that must be considered:
contributing to the hens' welfare, including whether hens are free to move; whether the system allows them to engage in behaviors that are normal for hens; whether they are protected from disease, injury, and predators; whether food and water are available in the appropriate amounts and type, and are of high quality; and whether the hens are handled properly.
For example, sows, known as the "mixing vessels" of avian influenza, are often raised in enclosed structures to prevent the spread of infectious diseases from wild animals and insect vectors. Their enclosures also protect them from exposure to parasites and protect the environment from their destructive rooting behavior and fecal contamination.
However, similar to public concerns about hen caged housing, bans on the use of gestation stalls for sows have been enacted throughout the country. Unfortunately, where these stalls are banned, hog farmers cannot provide updated sow housing techniques and equipment that allow sows a choice-protection in their stalls from aggressive animals or the ability to move around in the group-housing area.
As the AVMA has repeatedly pointed out, like for hens, there are pros and cons to every type of housing for sows. In a literature review and analysis, titled "Welfare Implications of Gestation Sow Housing" published on Nov. 19, 2015, the AVMA concluded:
Gestation sow housing systems vary in their advantages and disadvantages regarding the welfare of the sow. When comparing housing systems for pregnant sows, making a definitive welfare judgment requires assigning weights to an array of contributing welfare indicators including, but not limited to, type, severity and incidence of injuries; behavioral and social opportunities; and exposure to parasites, disease, and harmful or aversive stimuli. As no universally accepted weighting system exists, there is no clear consensus as to which is the superior system across all situations. However, the public is generally more critical of gestation stall housing than other systems, which has led to voluntary and mandatory transition to alternative housing systems by some producers. As such there is an ongoing need to develop an array of housing systems that suit local conditions, effectively provide enhanced opportunities for the sows to move and interact socially, and avoid an unacceptable increase in negative outcomes such as injury associated with aggression or exposure to environmental hazards.
Absolute bans on husbandry and housing techniques should be carefully considered, and informed by animal scientists, veterinarians, and the farmers who know the most about the needs of their animals.
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