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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #146377
Title: RISK FACTORS ASSOCIATED WITH CULLING FEMALES IN A COMPOSITE BEEF HERD

Author
item ROGERS, P - WASH STATE UNIV PULLMAN
item GASKINS, C - WASH STATE UNIV PULLMAN
item JOHNSON, K - WASH STATE UNIV PULLMAN
item Macneil, Michael

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2003
Publication Date: 6/1/2003
Citation: ROGERS, P.L., GASKINS, C.T., JOHNSON, K.A., MACNEIL, M.D. RISK FACTORS ASSOCIATED WITH CULLING FEMALES IN A COMPOSITE BEEF HERD. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT ABSTRACT #138. 2003. V. 81(SUPPL. 1). P. 34.

Interpretive Summary:

Technical Abstract: Our goal was to identify factors affecting risk of a beef female being culled. Data were from the CGC composite herd (1/2 Red Angus, 1/4 Charolais, 1/4 Tarentaise) at Miles City, MT in which heifers were exposed as yearlings. Binary logistic regression was used to assess factors affecting probability of calving as a 2-yr-old (P(C2), including heifer (n = 1,756) phenotypes and breeding values (BV). March-born heifers were more likely to calve at two than heifers born thereafter (P < 0.01). As birth weight of the heifer increased P(C2) tended to decrease (P < 0.10). Conversely, P(C2) tended to increase as BV for cow weight increased (P < 0.10). Neither phenotype nor direct and maternal BV for preweaning gain affected P(C2) (P > 0.10). Relationships of age at culling with first calving measurements (n = 1,254) and genetic profiles (n = 1,382) of females were assessed in separate analyses using Cox regression. Independent variables were coded into evenly spaced categories. Records from pregnant cows that were sold and from cows in the herd in 2001 were treated as censored (33%). Age at first calving and birth weight and 200-d preweaning gain of her first calf did not influence age at culling (P > 0.10), but heifers experiencing dystocia were at 36% greater risk than cohorts that did not (P < 0.01). As BV for cow weight increased, risk of being culled decreased (P < 0.01). Cows with intermediate direct BV for preweaning gain were at lower risk of being culled than those with extreme BV (P < 0.01). On average, increasing maternal BV for preweaning gain increased risk of being culled (P < 0.01). Date of birth was more important than phenotype or genetic profile in determining whether or not a heifer calves at 2 yr of age. Genetic profile of a female is a better indicator of age at culling than traits measured on her first calf.