Rearing and handling injuries in broiler chickens and risk factors for wing injuries during loading

Some injuries to broilers occur during rearing, but most injuries occur during handling before slaughter. Records provided by a processing plant for loads transported over a 19-month period during 2009 and 2010 were examined. The median percentage of wing injuries per load was 5.7%; while injuries to the legs, breast or shoulders were all less than 1% per load. Risk factors for wing injuries were examined by considering the data from each load by handling event (i.e. loads originating from the same producer on the same date). A multilevel model with three levels: producer (n=86), handling event (n=1694) and load (n=4219) was fitted. The final model included: weight, sex, season, catching team, time of day at which loading began, speed of loading, and an interaction between speed of loading and time of day. Factors that reduced the risk of wing injuries were loading lighter birds, loads containing only cockerels and loading in the fall. The predicted percentage of wing injuries was relatively constant for slower loading speeds but was increased significantly when faster loading speeds were adopted during daytime (0700 to 1700 h). Identification of these risk factors can be used to adjust loading practices.