Incidence, Severity, and Welfare Implications of Lesions Observed Postmortem in Laying Hens from Commercial Noncage Farms in California and Iowa.

The egg industry is moving away from the use of conventional cages to enriched cage and noncage laying hen housing systems because of animal welfare concerns. In this study, the prevalence and severity of lesions in noncage laying hens from commercial farms in two of the largest egg-producing states, California and Iowa, were evaluated by postmortem examination. Hens that died or were culled were collected during early, mid, and late stages of the laying cycle from 16 houses on three farms. Of the 25 gross lesions identified for study, 22 were observed, with an average of four lesions per hen. Vent cannibalism, reduced feather cover, keel bone deformation, and beak abnormalities were the most frequent lesions, observed in ≥40% of hens. Other common lesions were cloacal prolapse (30.5%), footpad dermatitis (24.3%), and septicemia (23.1%). Beak abnormality and enteric disease had the highest proportion of severe lesions. Pearson chi-square analysis revealed a number of stage-of-lay effects (P ≤ 0.05), some of which differed by state. For both states combined, the lesions observed more frequently during early lay were beak abnormalities, northern fowl mite infestation, and cage layer fatigue, whereas during mid lay, they were poor feather cover, vent cannibalism, footpad dermatitis, keel bone deformation, respiratory disease and roundworms. Feather pecking and cloacal prolapse were most common during late lay. Although differences in hen genetics, farm management practices, and environmental factors could all have affected the results of this study, the information provides a better understanding of hen health in noncage housing systems and could help to identify potential interventions to reduce hen welfare problems.