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Sire Breed Effects in Matings with Angus Cows: I. Fertility, Calf Survival and Performance to 18 Months^1,2,3,

Virginia Polytechnic Institute and State University^,6, Blacksburg 24061

Abstract

Over six calf crops, 524 exposures of Angus cows to three sire breeds resulted in 432 weaned calves for an 82.4% calf crop. Least squares means for weaning rate by sire breed were 81.8, 80.5 and 83.9% for Angus, Charolais and Holsteins, respectively. Sire breed effect was not significant for calving rate, calf mortality or overall weaning rate, but was significant for all growth traits from birth to 18 mo. Angus sired calves were smallest at birth, grew at a slower rate and were lightest in weight at all ages. Charolais sired calves were heaviest at all weigh periods and Holstein sired calves were intermediate. Holstein sired calves scored significantly lower for both grade and condition than did Angus and Charolais sired calves. Charolais sired calves had the highest grade. Calving rate tended to be influenced by the effect of cow (P<.10) and sire breed x year (P<.001). Calving rate was highest for 3-yr-old and for 6- to 10-yr-old cows and was also 1.5 percentage units higher for crossbred matings. Cow productivity (kg of calf weaned/cow exposed) is a combined measure of fertility, calf survival and weaning weight. Although sire breed did not significantly affect cow productivity (P<.20), actual values favored cows producing crossbred calves by 14 and 9 kg for Charolais and Holstein crosses, respectively. Likewise, weight differences at 18 mo favored these crosses by 50 and 32 kg for heifers and 72 and 62 kg for steers. Among the two crossbred types, Charolais x Angus heifers were 28 kg heavier (P<.05) than Holstein x Angus heifers at 18 mo but the 10 kg difference in steers was not significant. The fact that the large sire breeds produced calves with heavier weaning weights without demonstrating significant increases in overall productivity points out the importance of high weaning rates.

¹ Contributing to Regional Project S-10, Breeding Methods for Beef Cattle in the Southern Region.

² Submitted with the approval of the Director of the Virginia Agr. Exp. Sta.

³ Authors express their appreciation to E. M. Grizzard and W. E. Burgess of the Southampton Correctional Center for making cattle available and for assistance with data collection.

⁴ Present address: 831 Concord Place, Landsdale, PA.

⁵ Present address: Anim. Sci. Dept., North Carolina State Univ., Raleigh.

⁶ Dept. of Anim. Sci.