Predicting cattle age from eye lens weight and nitrogen content, dentition, and United States Department of Agriculture maturity score.
J Anim Sci
; 86(12): 3557-67, 2008 Dec.
Article
em En
| MEDLINE
| ID: mdl-18641181
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).
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Tamanho do Órgão
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Bovinos
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Dentição
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Cristalino
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Nitrogênio
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article