ESTIMATIONS OF INCIDENCE AND HERITABILITY OF TIBIAL DYSCHONDROPLASIA IN TURKEYS

The tibio-tarsal bones of 1120, pedigreed, male and female turkeys were examined for dyschondroplasia. The incidence of dyschondroplasia increased from 6 to 12 weeks, when 89% of toms and 74% of hens were affected but decreased thereafter. Dyschondroplastic bones were longer and more curved than healthy ones. In male birds, incurvation of bones was correlated with length of lesion. Tibial rotation seemed to be independent of the dyschondroplasia. Dyschondroplastic turkeys were heavier and exhibited higher early daily weight gain than healthy ones. The heritability of susceptibility to dyschondroplasia, estimated on 340 turkeys, was 0.16; heritabilities of lesion length, width and area were respectively 0.19, 0.04 and 0.15.