title: Predicting cattle age from eye lens weight and nitrogen content, dentition, and United States Department of Agriculture maturity score.
abstract: This research explores the relationship between generally accepted and alternative cattle age-prediction methods and chronological age. Cattle (n = 386) of documented ages ranging from 370 to 1,115 d of age were used. Dentition (DEN), USDA maturity score (MS), lens weight (LW), and lens total N (LN) content were used as possible predictors of age. Correlations with age were determined: LW (r = 0.77); DEN (r = 0.74); LN (r = 0.71); and MS (r = 0.64). Stepwise backward regression was used to generate an age prediction equation: Age (mo) = -21.79 + 17.23(LW, g) + 0.038(DEN). By this equation, 38% of cattle </= 20 mo of age were verified as </= 20 mo of age. Independent measures verified the following percentages of cattle as </= 20 mo of age: LW (20.2%), MS (11.0%), DEN (9.6%), and LN (8.7%). The DEN verified that 87.6% were verified as <30 mo old, and LW verified 81.6% of cattle as <30 mo old. A separate group of cattle (n = 18) ranging in age from 1 to 12 yr were evaluated for lens properties, for which LW (R(2) = 0.91) and LN (R(2) = 0.92) were highly correlated with age. The LW and DEN were the best predictors of age for cattle 13- to 37-mo-old and yielded the most accurate age prediction when used in combination (R(2) = 0.67).
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Raines
authors.forename: M E
authors.initials: ME
authors.lastname: Dikeman
authors.forename: J A
authors.initials: JA
authors.lastname: Unruh
authors.forename: M C
authors.initials: MC
authors.lastname: Hunt
authors.forename: R C
authors.initials: RC
authors.lastname: Knock
mesh_terms: D000366:Age Determination by Teeth / Q000662:veterinary; D000367:Age Factors; D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology; D003817:Dentition; D005260:Female; D007908:Lens, Crystalline / Q000737:chemistry* / Q000502:physiology*; D008297:Male; D009584:Nitrogen / Q000032:analysis*; D009929:Organ Size / Q000502:physiology*; D011237:Predictive Value of Tests; D014481:United States; D016885:United States Department of Agriculture
chemical_list: D009584:Nitrogen