Trends in calving ages and calving intervals for dairy cattle breeds in the United States
Trends in calving ages and calving intervals for dairy cattle breeds in the United States
复制标题
DOI：
10.3168/jds.s0022-0302(06)72102-6
复制
发表时间：
2006-01-01
影响因子：
3.5
通讯作者：
Wright, JR
中科院分区：
文献类型：
--
作者：
Hare, E;Norman, HD;Wright, JR
对美国5个奶牛品种的产犊年龄和产犊间隔这两个影响牛群寿命的因素进行了产次检验。产犊数据来自记录通过美国农业部遗传评估编辑的奶牛，并且是仍在进行奶牛群改进测试的牛群。随着时间的推移，第一胎小母牛的产犊年龄逐渐变小，但由于产犊间隔较长，后期产犊的年龄下降较小。产犊年龄的品种差异在所有胎次中都很明显；目前第一次产犊的平均年龄从球衣的24mo到Ayrshires的28mo不等。所有品种的平均产犊年龄随着时间的推移而下降，主要是因为周转率增加，范围从荷斯坦的48mo到Ayrshires的54mo。在整个产次中，除泽西品种(0.49天/年)外，所有品种的产犊间隔年增长都相当一致(0.90至1.07天/年)。在胎次内，产犊间隔对年份的回归与整个品种的趋势大体相似。第一次产犊间隔的平均繁殖时间为390天(球衣)到407天(棕色瑞士)。
Trends since 1980 for calving age and calving interval, 2 factors that influence herd life, were examined by parity for 5 breeds of US dairy cattle. Calving data were from cows with records that passed edits for USDA genetic evaluations and were in herds that remained on Dairy Herd Improvement test. First-calf heifers calved at progressively younger ages over time, but the age decline was less for later parities because of longer calving intervals. Breed differences for calving age were evident for all parities; current mean age at first calving ranged from 24 mo for Jerseys to 28 mo for Ayrshires. Mean calving age across all parities declined over time for all breeds, primarily because of increased turnover rate, and ranged from 48 mo for Holsteins to 54 mo for Ayrshires. Across parity, annual increase in calving interval was reasonably consistent (0.90 to 1.07 d/yr) for all breeds except Jersey (0.49 d/yr). Within parity, regressions of calving interval on year were generally similar to overall breed trend. Breed means for first calving interval across time ranged from 390 d for Jerseys to 407 d for Brown Swiss.