title: Effects of divergent selection for incidence of tibial dyschondroplasia (TD) on purebred and crossbred performance. 1. TD incidence and calcium and phosphorus plasma concentrations.
abstract: 1. The effect of divergent selection for high (H) or low (L) incidence of tibial dyschondroplasia (TD) for 7 generations on blood calcium (Ca) and phosphorus (P) concentrations was studied. 2. The chicks used in this experiment were obtained from diallel crosses between H and L lines to obtain HH, HL, LH, and LL lines. A random-bred control (CC) line was also used. 3. The chicks were reared under standard management conditions. Body weight and plasma Ca and P concentrations were measured at 2, 4, and 7 weeks of age. Incidence of TD was recorded at 4 and 7 weeks. 4. Although HH birds had lower body weights than the other lines, there was no significant effect attributable to line selection for body weight at 2, 4, and 7 weeks of age. 5. The LL line birds had no incidence of TD at 4 weeks of age; however, the incidence of TD in LL line birds was 5.3% at 7 weeks of age. The incidence of TD was higher in HH line birds than the other line at 4 and 7 weeks of age. 6. Plasma Ca and P concentrations and Ca:P ratios increased with age. These results showed that HH line birds had higher plasma Ca, lower plasma P and higher Ca:P ratios than birds of the LL line.
authors.affiliation: Department of Animal Science, Faculty of Agriculture, Ege University, Izmir, Turkey. yalcin@ziraat.ege.edu.tr
authors.forename: S
authors.initials: S
authors.lastname: Yalçin
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: L M
authors.initials: LM
authors.lastname: Christa
authors.forename: G R
authors.initials: GR
authors.lastname: McDaniel
authors.forename: D L
authors.initials: DL
authors.lastname: Kuhlers
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000097:blood*; D002645:Chickens / Q000235:genetics* / Q000502:physiology; D003433:Crosses, Genetic; D005260:Female; D008297:Male; D010009:Osteochondrodysplasias / Q000097:blood / Q000235:genetics / Q000517:prevention & control / Q000662:veterinary*; D010758:Phosphorus / Q000097:blood*; D011201:Poultry Diseases / Q000097:blood / Q000235:genetics* / Q000517:prevention & control; D011897:Random Allocation; D012641:Selection, Genetic; D012737:Sex Factors; D013977:Tibia / Q000473:pathology*
chemical_list: D010758:Phosphorus; D002118:Calcium