|MARQUEZ A P|
|VAN VLECK L DALE|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/1995
Publication Date: N/A
Technical Abstract: Cows were F1 and backcrosses from original matings of Hereford, Angus, Pinzgauer, Brahman, and Sahiwal bulls to Hereford and Angus cows. Matings of the 146 cows were in multiple (unidentified) sire pastures to produce calves at 2 and 3 yr of age from Red Poll (n=86) and Longhorn (n=81) bulls. Calving difficulty of the Red Poll sired calves was greater for calves of 2-yr-old cows (1.36 plus/minus .24) on a categorical scale (1, no difficul ty, to 7, caesarean) and (-.31 plus/minus .07) on a binomial scale (1 for categorical scores of 1 and 2, little difficulty by hand; and 0 for cate- gorical scores of 3 to 6) as compared to Longhorn sired calves. No differ- ences due to sire breed for calving difficulty was found for 3-yr-old cows. Calves of 2-yr-old cows mated to Red Poll bulls were heavier at birth (3.6 plus/minus 1.2 kg) and at weaning (21.0 plus/minus 7.1 kg) than calves of Longhorn bulls. Birth and weaning weights of calves of 3-yr-old cows were slightly heavier (1.1 and 5.4 kg, respectively) when sired by Red Poll tha by Longhorn bulls. There was no difference in survival rate to weaning for Red Poll and Longhorn sired calves. Regression on breed inheritance of dams indicated cows with Sahiwal and Brahman inheritance had the smallest calves at birth. Pinzgauer and Brahman inheritance resulted in the largest calves at weaning. Sahiwal, Brahman, and Pinzgauer inheritance in cows resulted in less calving difficulty than Angus and Hereford inheritance. The dam component of variance as a fraction of the phenotypic variance was .48 for birth weight, .45 for weaning weight and .10 and .04 for calving difficulty measured categorically and binomially, respectively.