PERFORMANCE OF THREECROSS AND HEREFORD COWS. I. REPRODUCTIVE CHARACTERISTICS
Abstract
The performance of six groups of threecross and straightbred Hereford cows was studied during a period of six years. The crossbred cows were produced by F, 1/2 Charolais (C) — Hereford (H), 1/2 Holstein (Ho) — Hereford (H) or 1/2 Sta. Gertrudis (SG)—Hereford (H) dams mated to Nelore (N) and A. Angus (A) bulis. The six groups of threecross and the straightbred Hereford cows were artificially inseminated with semen from Hereford bulis. The experiment was conducted at Estação Experimental tal Zootecnica, Uruguaiana-RS. Weaning rate for crossbred cows ranged from 46% (2/4 N 1/4 SG 1/4 H) to 65% (3/4 N 1/4 C 1/4 H (P>0.05). The smallest productivity (kg of calf weaned/cow exposed) was observed for the H cow (59 kg) while the highest was observed for the 2/4 N 1/4 C 1/4 H cows (115.9 kg) (P<0.05). Gestation period was not affected (P>0.05) by the genetic group of the cow, and ranged from 281.1 days, for the 2/4 N 1/4 Ho 1/4 H cows, to 284.2 days for the H cows. The cows daughters of Nelore sires presented 56.8% weaning rate, 100.5 kg of calf/cow exposed and had a 283.6 days gestation period, while the daughters of A. Angus sires presented 58.5% weaning rate, 87.5 kg of weaned calf/cow exposed and showed a 283.2 days of gestation period (P>0.05). The breed of the cow's grandfather did not affect (P>0.05) any of the reproductive traits studied.
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