[Tibial dyschondroplasia in broiler chickens]

After the general description of tibial dyschondroplasia (TD) an account is given on observations of the incidence of this leg abnormality in the Danish broiler production. Comparative investigations concerning the frequency of TD in three commercial strains of broiler chickens (A, B & C) is described. The possible effect of the diet, with reference to frequency--particularly calcium and phosphorus levels--is studied. Chickens from each strain were divided into two equal groups; one was fed an ordinary broiler chicken diet (X), and the other was given feed (Y) originally composed for replacement pullets. The frequency of TD was 22 percent in broiler chickens from the commercial production. Irrespective of composition of the feed, almost the same incidence was recorded in both groups of one of the strains (A), while the frequency of TD in strains B & C was significantly lower on both diets. In relation to available observations and results, influence on incidence of genetic factors and certain feed ingredients is discussed. It is concluded that the TD-frequency is relatively high in the strain which dominates the Danish broiler production. This seems to be primarily determined by genetic factors, whereas in this experiment the levels of calcium, phosphorous and other feed ingredients have minor influence.