Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 1998
Publication Date: N/A
Interpretive Summary: An important element in optimizing cow-calf production is the selection of the breed of cow that matches the producers environment and management style. The overall efficiency of a production system may be increased if inputs are decreased and subsequent performance is maintained. Development of heifers represent a substantial input cost to the production system. This study demonstrates that heifers raised on a moderate level of nutrition before breeding perform similarly to heifers raised on high levels of nutrition. This study suggests that the efficiency of heifer development can be increased by moderate levels of feeding. This study further demonstrated that heat-tolerant breeds differ in their ability to produce milk and in calf growth rates suggesting that these breeds can be matched to feed availability in different United States subtropic environments.
Crossbred heifers produced from seven breeds of sires (Hereford, Angus, Belgian Blue, Piedmontese, Brahman, Boran, and Tuli) bred to three breeds of cows (Angus, Hereford, and MARC III [four-breed composite]) were evaluated. Heifers were mated to Red Poll sires to calve at 2 yr of age. Heifers were placed in three treatment groups from weaning to breeding and raised on a high nutrition level (15.8 Mcal ME/d), raised on 80% of high nutrition (12.6 Mcal ME/d), or fed as a mixed- breed group (16.3 Mcal ME/d). Breed and treatment groups did not differ in the age of the heifer at parturition. Birth weights of calves differed by maternal-grandsire (P < .001) but not by dam treatment group (P = .88) or maternal-grandam (P = .68). Cows did not differ in their postpartum interval by sire breed. Calf age at weaning differed with the breed of the cows maternal-grandsire (P < .001). Calf ADG (P < .001) and 205-d weight (P < .001) differed with different maternal grandsires. Milk production from 50 to 200 d of lactation was greatest for cows with Belgian Blue and Brahman sires. Milk production did not differ with treatment group (P = .84). These studies suggest that over a diverse group of breeds, accelerated rates of gain during the postweaning period within the ranges of this study do not result in increased production efficiency of the cow. Proper selection of the appropriate breed for a production system can optimize performance of the cow herd.