HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Urick, J. J. Articles by Blackwell, R. L. Search for Related Content PubMed Articles by Urick, J. J. Articles by Blackwell, R. L.

A Comparison of Crossbred and Straightbred Cow-Calf Pairs. I. Heterosis Effects on Total Feed Efficiency¹

US Department of Agriculture and Montana Agricultural Experiment Station, Miles City 59301, Cooperating

Abstract

Records of 104 crossbred and 33 straightbred individually fed cow-calf units were used to study the effects of heterosis on total cow-calf feed efficiency in the production of weight of calf at weaning, 168 d postweaning, slaughter and in the carcass. The cows were Angus, Hereford, Charolais and reciprocal crosses of these breeds. The calves were straightbred and all possible two-breed backcrosses and three-breed crosses produced from first cross cows. The efficiency of the cow-calf unit was defined as kg of calf produced per kg of total TDN (total digestible nutrients) consumed by the cow-calf pair. Total feed consumed by the cows was for an average period of 315 d, from approximately November 21 to October 2. Total calf TDN consisted of creep to weaning and feed during the postweaning fattening period to slaughter. For all measures of cow-calf unit efficiency studied, the heterosis estimates were small but generally positive, ranging from –.8 to 2.1%. The average advantage of all crosses over the straightbred parents for the conversion of total feed consumed by cow-calf pair to calf weight at weaning was 2%. Heterosis effects, individual and maternal combined, on the average, among two-breed backcrosses and the three-breed crosses were essentially the same. Among the three groups of first-cross cows compared, the study indicated that a slight advantage in total cow-calf efficiency was exhibited by the Angus x Hereford cross. Breed fo cow was a significant source of vairation for all body weights and measurement taken and for total feed consumed. However, hetorosis did not influcence these same cow traits significantly except that Angus x Charolais cows were heaview (26 kg) than the average of parent breeds. In the calf data, breed was a significant source of variation for all weights and efficiency traits excluding efficiency to weaning. Sex of calf was a significant source of variation for all traits.

¹ This research is a contribution from the Western Region, USDA,ARS-WR, Livestock and Range Res. Sta. and the Montana Agr. Exp. Sta., Journal Series No. 1375.

² Authors are Research Animal Scientists, Geneticsts, USDA SEA-AR, Livestock and Range Research Station, Route 1, Box 2021, Miles City, MT 59301.

³ Present address: Biometrical Services, ARS, USDA, Fort Collins, CO 80521.

⁴ Montana Agr. Exp. Sta., Bozeman, MT 59717.