title: The incidence and importance of tibial dyschondroplasia to the commercial broiler industry in Australia.
abstract: 1. To survey the relationship between tibial dyschondroplasia (TD) and the down-grading of broiler carcasses three processing plants representing the major breeding and growing organizations in Australia were visited. 2. The incidence of TD for the three flocks examined varied from 14 to 35%. In the flock with the highest incidence of TD there was a direct relationship between the presence of TD and down-grading of carcasses due to leg abnormalities. 3. A genetic analysis was carried out on one of the parent lines of the breeding group with the highest TD incidence. The genetic correlation between body weight and TD incidence at 7 weeks of age was negative, suggesting that continued selection for increased body weight should lead to a reduced incidence of TD. Since this conflicts with usual expectations, possible reasons, including a within-line genotype by environment interaction, are discussed. 4. Because of the substantial genetic component associated with TD, screening of breeding cockerels for its presence if strongly recommended.
mesh_terms: D000818:Animals; D001315:Australia; D002645:Chickens / Q000235:genetics; D005260:Female; D005525:Food-Processing Industry; D008297:Male; D008460:Meat; D010009:Osteochondrodysplasias / Q000453:epidemiology / Q000235:genetics / Q000662:veterinary*; D011201:Poultry Diseases / Q000453:epidemiology* / Q000235:genetics; D011786:Quality Control; D012737:Sex Factors; D013977:Tibia