Bone fracture incidence in end-of-lay high-producing, noncommercial laying hens identified using radiographs

Bone fractures in laying hens are both a welfare and an economic concern for the poultry industry. The aim of this study was to use radiographs to quantify fracture incidence in 6 lines of noncommercial high-producing laying hens. A total of 451 hens (n = 71 to 78) were killed at 47 wk (White Leghorn-Black, White Leghorn-Blue) or 65 wk of age [Barred Plymouth Rock (BR), White Leghorn-Burgundy (WL-BUR), Columbian Plymouth Rock, Rhode Island Red (RIR)]. Radiographs were obtained with hens in 2 positions (lateral and ventrodorsal) and were used to identify fractures in the skeleton. Data on scallop-shaped indentations (possibly fractures) of the keel bone were also collected. After radiography, the left wings were removed for analysis of humeri, radii, and ulnae. Data for the 2 age groups were analyzed separately. The overall incidence of hens with at least 1 fracture was 6.6 and 15.7% in the 47- and 65-wk-old hens, respectively. Fracture incidence in 47-wk-old hens was not different between White Leghorn-Black and White Leghorn-Blue lines. Significant line differences were observed in the 65-wk-old hens, with at least 1 fracture found in 29.5% of RIR hens versus 9.5 and 4.2% observed in Columbian Plymouth Rock and WL-BUR lines, respectively. Fracture incidence in BR hens (18.2%) was greater than in WL-BUR hens. Fractures in RIR hens occurred predominantly in the furculum and wing bones, whereas pubic bones were most affected in BR hens. The proportion of hens with scallop-shaped indentations of the keel ranged from 36.1 to 88.2% and differed between lines in both age groups. High egg production did not seem to be associated with bone fragility in these lines. Two of the older lines (RIR and WL-BUR) had similar egg production, number of eggs to 60 wk, and egg shell weights at 4 ages but had a significantly different fracture incidence. The line differences in fracture incidence may have been affected by calcium metabolism, bone structure, and body weight.