U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report, No. 4, Part 2 (May 1993)


Beef cattle production entails the conversion of plant resources not normally considered as part of the food chain for humans into a food resource that partially fulfills human dietary needs. Traditionally, the beef industry has been segregated into production components, each having its own marketing endpoint. The cow/calf component of the industry produces progeny for introduction into the food chain conversion process. Energy and protein requirements of the commercial cow herd should be fulfilled as much as possible through direct harvest of forages by the animals. Within the U.S., a wide range of forage production environments exist. Commercial producers have the flexibility to identify breeds or breed crosses to be used as producing females and to identify sire breed or breed crosses to mate with these cows. Previous research at U.S. Meat Animal Research Center has demonstrated variation among and within breeds for traits affecting weight of calf produced at weaning. Cows representative of breeds with greater genetic potential for growth and lactation yield have been shown to produce calves that are heavier at weaning. Additional research at U.S. Meat Animal Research Center has documented a positive relationship between genetic potential for production and energy requirement to maintain body weight of the cow. Differences in energy required to sustain the producing female suggest that breeds or breed crosses can be identified that are more effective in the conversion of forage resources into amarketable product. Earlier work conducted at U.S. Meat Animal Research Center indicated that breed crosses more moderate in growth potential and lactation yield, were more effective in preweaning weight production of calves. The objective of the study was to determine if differences exist among breeds of beef cattle in the efficiency of converting food energy to weight of calf at weaning.