McCarter M N, Buchanan D S, Frahm R R
Oklahoma Agricultural Experiment Station, Stillwater 74078-0425.
J Anim Sci. 1990 Jun;68(6):1547-52. doi: 10.2527/1990.6861547x.
Productivity of 2-yr-old crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding was evaluated using 203 spring-calving and 171 fall-calving heifers over a 3-yr period. All heifers were mated to Limousin sires. Percentage of cows exposed to breeding that weaned a calf was the only trait for which a significant crossbred cow group x season of calving interaction was found. Preweaning ADG and age-adjusted weaning weight increased as proportion Brahman breeding increased. Age-adjusted weaning weight was similar for the two groups because spring-born calves were weaned at an average age of 205 d and fall-born calves were weaned at an average age of 240 d. For weaning condition scores, an interaction between dam breed and proportion Brahman was detected; scores tended to be greater for calves out of 1/2 Hereford dams than for those out of 1/2 Angus dams, and this difference increased as proportion Brahman increased. Weaning conformation scores were similar for all calves. Age-adjusted weaning hip height increased as proportion Brahman breeding increased. Based on numbers of weaned calves, spring calving was more advantageous than fall calving. Averaged across both calving seasons, weaning weight tended to increase as proportion Brahman increased.
在3年时间里，使用203头春季产犊和171头秋季产犊的小母牛，对含有不同比例（0、1/4或1/2）婆罗门牛血统的2岁杂交母牛的生产性能进行了评估。所有小母牛均与利木赞公牛交配。产犊季节与杂交母牛组之间唯一有显著交互作用的性状是产犊后成功断奶的母牛比例。随着婆罗门牛血统比例的增加，断奶前平均日增重和年龄校正断奶体重也随之增加。由于春季出生的犊牛平均在205日龄断奶，秋季出生的犊牛平均在240日龄断奶，因此两组的年龄校正断奶体重相似。对于断奶状况评分，检测到母本品种与婆罗门牛血统比例之间存在交互作用；1/2赫里福德母牛所产犊牛的评分往往高于1/2安格斯母牛所产犊牛，且这种差异随着婆罗门牛血统比例的增加而增大。所有犊牛的断奶体型评分相似。随着婆罗门牛血统比例的增加，年龄校正断奶臀高也随之增加。基于断奶犊牛的数量，春季产犊比秋季产犊更具优势。在两个产犊季节中，随着婆罗门牛血统比例的增加，断奶体重总体呈上升趋势。
