Production, Management and the Environment: Poultry

The objective of the following study was to determine the incidence of tibial dyschondroplasia (TD) among 4 crosses (crosses A, B, C, and D) of male meat-type commercial broilers and its relationship to gait score at 6 wk of age. At 38 and 39 d of age, 360 birds were evaluated individually for gait score. Three male chickens/pen with good walking ability (gait score of 0 or 1) and 3 male chickens/pen with poorer walking ability (gait score of 3) were killed and individual BW determined at 6 wk of age. Both drumsticks were retrieved and the distal and proximal tibia were scored for TD lesion (0 = no lesion; 1 = mild lesion; 2 = moderate lesion; and 3 = severe lesion). Data were analyzed via ANOVA using the mixed model procedure of SAS. Very few birds showed TD lesions. The TD scores were similar among crosses even though gait scores differed among genotypes with cross C having better gait scores than crosses A and B but did not differ from cross D. The TD lesion scores did not differ between male broilers with a gait score of 0 or 1 (mean TD lesion score of 0.03 ± 0.03) as compared with those with a poorer walking ability and a gait score of 3 (mean TD lesion score of 0.08 ± 0.03). The proximal end of the right and left tibia had similar TD lesion scores. The TD lesions scores were higher for the right proximal tibia when compared with the distal ends of the right and left tibia. These results suggest the poorer walking ability of male broilers in this study was not due to TD lesions.