The effect of housing environment (deep litter with or without access to different plant species outdoor) on welfare and behavior across two strains of laying hens.

The impact of the housing environment and hen strain on the welfare and behavior of laying hens was the focus of this study. Lohmann LSL Classic (W) and Lohmann Sandy (S) were assessed under deep litter without outdoor access (DL), deep litter with access to outdoor pens covered with either Mentha piperita (MP), Petroselinum crispum (PC) or Medicago sativa (MS). Duration of tonic immobility, feather condition, footpad dermatitis, and temperatures (comb, breast region, footpad surface, and rectal) were determined at 31, 42, and 52 weeks of age. Hen's behaviors were observed at 32, 42, and 52 weeks of age. Blood parameters were assessed at 52 weeks of hen age. Duration of tonic immobility was similar between hen strains and across ages of hens (p > 0.05) but nearly reached significant levels due to the housing environment (p = 0.070). There was a significant effect of age (p < 0.001), housing environment (p < 0.001), and hen strain (p < 0.05) on total feather score. Age-related effects were observed for all the body region temperatures (p < 0.001), and only the comb and rectal temperatures differed between hen strains (p < 0.001; p < 0.05). The housing environment did not affect the body surface temperatures (p > 0.05). Blood parameters did not differ between hen strains and housing environments (p > 0.05). There was a significant effect of age, housing environment, and hen strain on the proportion of hens expressing some behaviors (p < 0.001; p < 0.05). Time of the day influenced the proportion of birds expressing wing flapping and dust bathing behaviors (p < 0.05). It was concluded that feather condition varies with the housing environment and hen strain, duration of tonic immobility may differ across housing environments, but other welfare traits remain to be refined. Also, housing environment but not strain modulates the expression of most behaviors of hens. [ABSTRACT FROM AUTHOR]