Effect of Selection for High or Low Incidence of Tibial Dyschondroplasia for Seven Generations on Live Performance

Abstract

An experiment was conducted to determine the effect of divergent selection for tibial dyschondroplasia (TD) on live performance of broilers. Broilers used in the experiment were produced from the parental lines selected for high (H) and low (L) incidence of TD and a randombred control (C) line. Diallel crosses were made between H and L lines. The offspring produced were HH, HL, LH, LL, and CQ where the first letter refers to sire line and the second letter refers to dam line. Body weights, average daily body weight gains, and exponential growth rates were determined at weekly intervals. The incidence of TD was recorded at 4 and 7 wk of age.There was no difference among body weights of lines up to 5 wk of age. Sire lines influenced body weights of birds from 5 to 7 wk of age. A significant interaction between sire and dam lines for body weight was the result of decreased body weights of birds in the HH line from 5 to 6 wk of age. There was a similar interaction for body weight gain, which resulted in a slower growth rate of birds in the HH line from 3 to 5 wk of age. Tibial dyschondroplasia incidence was 84.1 and 92.0% in the HH line, 5.6 and 5.4% in the LL line, and 7.0 and 13.2% in the CC line at 4 and 7 wk of age, respectively. It was suggested that genetic predisposition for TD was independent of body weight.