J. Anim Sci.
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J. Anim Sci. 2008. 86:3557-3567. doi:10.2527/jas.2007-0445
© 2008 American Society of Animal Science
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ANIMAL PRODUCTS

Predicting cattle age from eye lens weight and nitrogen content, dentition, and United States Department of Agriculture maturity score1,2

C. R. Raines*, M. E. Dikeman*,3, J. A. Unruh*, M. C. Hunt* and R. C. Knock{dagger}

* Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506; and {dagger} Department of Animal Science, Iowa State University, Ames 50011

3 Corresponding author: mdikeman{at}ksu.edu

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 (R2 = 0.91) and LN (R2 = 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 (R2 = 0.67).

Key Words: age verification • cattle maturity • dentition • lens






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