title: The anterior tooth development of cattle presented for slaughter: an analysis of age, sex and breed.
abstract: In a cross-sectional study, data from records of cattle slaughtered over a 1-year period at a large abattoir in South West England were analysed using an ordered category response model to investigate the inter-relationships between age, sex and breed on development of the permanent anterior (PA) teeth. Using the model, transition points at which there was a 50% probability of membership of each category of paired PA teeth were identified. Data from ∼60,000 animals were initially analysed for age and sex effect. The age transition was found to be ∼23 months moving from zero to two teeth; 30 months for two to four teeth; 37 months for four to six teeth and 42 months for six to eight teeth. Males were found to develop, on average, ∼22 days earlier than females across all stages. A reduced data set of ∼23,000 animals registered as pure-bred only was used to compare breed and type interactions and to investigate sex effects within the sub-categories. Breeds were grouped into dairy and beef-type and beef breeds split into native and continental. It was found that dairy-types moved through the transition points earlier than beef-types across all stages (interval varying between ∼8 and 12 weeks) and that collectively, native beef breeds moved through the transition points by up to 3 weeks earlier than the continental beef breeds. Interestingly, in contrast to beef animals, dairy females matured before dairy males. However, the magnitude of the difference between dairy females and males diminished at the later stages of development. Differences were found between breeds. Across the first three stages, Ayrshires and Guernseys developed between 3 and 6 weeks later than Friesian/Holsteins and Simmental, Limousin and Blonde Aquitaine 6 and 8 weeks later than Aberdeen Angus. Herefords, Charolais and South Devon developed later but by a smaller interval and Red Devon and Galloway showed the largest individual effect with transition delayed by 8 to 12 weeks.
authors.affiliation: Corners, Smithincott, Cullompton EX15 3DG, UK.
authors.forename: K J
authors.initials: KJ
authors.lastname: Whiting
authors.forename: S N
authors.initials: SN
authors.lastname: Brown
authors.forename: W J
authors.initials: WJ
authors.lastname: Browne
authors.forename: P J
authors.initials: PJ
authors.lastname: Hadley
authors.forename: T G
authors.initials: TG
authors.lastname: Knowles
mesh_terms: D000003:Abattoirs; D000375:Aging; D000818:Animals; D002417:Cattle / Q000235:genetics / Q000254:growth & development*; D003430:Cross-Sectional Studies; D003481:Cuspid / Q000254:growth & development*; D019229:Dentition, Permanent; D004739:England; D005260:Female; D007180:Incisor / Q000254:growth & development*; D008297:Male; D015233:Models, Statistical; D012727:Sex Characteristics; D013045:Species Specificity