Abstract
Feather pecking is a behavior that occurs in order to cope with a constrained environment and is a serious problem in the egg production industry. This longitudinal study was conducted under commercial conditions to investigate whether the application of two repellent mixtures, previously suggested as aversive to wild birds, to the plumage of Prelux-R hybrid egg layers is a viable alternative to beak trimming as a solution to discourage feather pecking among laying hens. A total of 180 untrimmed hybrid layers was reared together in a floor pen. At 18 weeks of age they were allocated randomly to three treatments (repellent P, repellent T, control), each consisting of 6 replicated enriched cages with 10 hens in each cage. Hens were evenly sprayed once every 2 weeks for 54 weeks with solution P (dimethyl anthranilate and methyl phenylacetate), solution T (dimethyl anthranilate and geraniol), or distilled water (control). Body weight, plumage condition, behavior, feed intake, and egg quality measurements were taken at five time periods from 26 to 76 weeks of age. Egg production and mortality were recorded daily. The treatments did not affect feather pecking behavior. Hens treated with repellent T tended to perform less cage pecking than the control hens. The use of the repellents did not reduce feather pecking, the plumage was even more significantly damaged in the hens given the repellents compared to the control hens. This suggests the chemicals in the repellents worsened the plumage. No differences in feed intake and daily egg production between treatments were found. Raw and hard-boiled eggs were highly uniform in odor/flavor/taste and no offensive odor absorption related to the chemicals in the repellents was detected. In conclusion, in the present study we did not find any beneficial effect of dimethyl anthranilate-based repellents on feather pecking frequency and plumage/feather condition. Therefore, we do not encourage their use in wider commercial settings.
Highlights
In modern systems for housing laying hens, producers often encounter two injurious behaviors: severe feather pecking and cannibalism, which represent a big problem from economic and animal-welfare points of view [1]
The limited number of valuable studies available reveals that spraying feathers with repellents may help reduce the incidence of feather pecking, but the results of these studies are difficult to extrapolate to commercial practice because they were performed on experimental lines of chickens [e.g., [13, 14]], used toxic repellents, e.g., quinine [e.g., [13, 14]], or were conducted in conditions vastly different from those found on a commercial farm [e.g., [15]]
Chemical repellents like dimethyl anthranilate (DMA), methyl phenylacetate (MPA), and geraniol are already used to control avian crop depredation and nuisance problems [16,17,18]. Their repellent effects on wild birds have been known for many years, little has been done to develop them for practical use to improve the welfare of laying hens
Summary
In modern systems for housing laying hens, producers often encounter two injurious behaviors: severe feather pecking and cannibalism, which represent a big problem from economic and animal-welfare points of view [1]. Chemical repellents like dimethyl anthranilate (DMA), methyl phenylacetate (MPA), and geraniol are already used to control avian crop depredation and nuisance problems [16,17,18] Their repellent effects on wild birds have been known for many years, little has been done to develop them for practical use to improve the welfare of laying hens. Kare’s report [18] mentions that DMA, MPA, and geraniol may either individually or in combinations thereof be very effective as anti-pecking agents for chickens This record prompted us to evaluate the efficacy of two proposed repellent mixtures on the incidence and extent of feather pecking and other behaviors in a flock of commercial laying hens. We formulated the following hypotheses: a) dimethyl anthranilate-based repellents will deter hens from feather pecking and plumage will be less damaged in the repellent treatments than in the control treatment; b) hens in the repellent treatments will have better production results; and c) the repellents will not affect the eggs’ organoleptic properties, which is vital information for both the egg processing industry and egg consumers
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