Floor Substrate Preferences of Chickens: A Meta-Analysis.

Environmental enrichment promotes sensory and motor stimulation for species-typical behaviors, which in turn enhance animal well-being. For farmed Galliformes, housing systems often limit enrichment to bedding and litter, that simultaneously act as material for dustbathing and foraging. Therefore, this meta-analysis sought to systematically review and synthesize the substrate preference test literature for Galliformes. Data based on the following four welfare-related behaviors were extracted for analysis: (1) dustbathing, (2) foraging, (3) pecking, and (4) time spent on a given substrate. Literature searches in CAB Direct, Web of Science, and Google Scholar yielded 239 articles, and hand searching yielded an additional five articles. Ten publications that used different chicken strains as test subjects, met the criteria to be included in the systematic review. The effects of bedding type, the number of days birds had access to tested substrates, enclosure area, and substrate area, on the examined behaviors were determined. We found that birds preferred dustbathing in sand and peat moss more than on any other substrates. The bedding type, size of the enclosure, and size of the substrate area affected the amount of time that birds spent on the tested substrates. When provided the choice between bedding materials, birds spent more time on sand or peat moss than on any other substrate or on no substrate. Notably, most studies did not report relevant physical or chemical characteristics of substrate that may influence birds' preferences, such as grain size, moisture content and the level of soiling. Focusing future studies on identifying substrate characteristics that influence preferences can lead to the discovery of new, practical, enriching beddings that can be easily implemented in housing systems for Galliformes.

Are Turkeys (Meleagris gallopavo) Motivated to Avoid Excreta-Soiled Substrate?

The soiling of bedding on modern turkey farms combined with turkeys' reduced ability and opportunity to perch and roost at elevation, forces them to spend most, if not all, of their time in contact with their excreta. To determine turkeys' perspective on these conditions and the value they place on unsoiled bedding vs. soiled litter (collectively, substrates), we used twenty-four eleven-week-old turkey hens divided into six two-compartment pens. In the "home" compartment (H), we placed soiled wood shavings, while the "treatment" compartment (T) contained no substrate (NS), fresh pine and spruce wood shavings (FP), soiled pine and spruce wood shavings (SP), ammonia reductant-treated soiled pine and spruce wood shavings (TSP), or a feed treatment. One-way push-doors separated the two compartments. The door leading to T weighed an additional 0%, 20% or 40% of the turkeys' body weight while the door to H remained unweighted. All birds were exposed to each resource and door weight combination in a systematic order. We measured the turkeys' motivation based on the number of birds that pushed the maximum weight to access each resource, the amount of time spent in T, and the number of visits to T. Our findings show that turkeys worked harder to access feed compared to all the floor substrate treatments. Additionally, they were equally motivated to access all the substrate treatments.

Broiler Chicks' Motivation for Different Wood Beddings and Amounts of Soiling.

In the wild, excreta soiled surroundings can attract predators and spread disease. Yet, farmers rear broiler chicks in large barns with stocking densities that prevent excreta segregation. To measure chicks' motivation to access unsoiled bedding or soiled litter (collectively, substrates) we used 40 16-day-old broiler chicks who were divided into six two-compartment pens. The 'home' compartment (H) contained soiled wood shavings, while the 'treatment' compartment (T) contained either aspen wood shavings, pine and spruce wood shavings, soiled pine and spruce wood shavings, ammonia reductant treated soiled pine and spruce wood shavings, or a feed treatment as a gold standard. The barrier separating the compartments had two one-way push-doors that chicks pushed to access a resource. The chicks' motivation was measured by the average maximum weight pushed to access each resource. The door leading to T weighed 0% (raised), 10%, 20%, or 30% of the chicks' body weight, and chicks could return to H via a raised (for 0%) or unweighted door. Our findings indicate that chicks worked hardest for feed, but paid a lower, equal price to access all substrates. With increasing door weight, chicks visited less and spent less time with the substrates. Therefore, as chicks themselves do not avoid litter that could have potential negative effects on their well-being, it is important that farmers diligently monitor litter conditions as their primary care-takers.