Hackett A J, Batra T R, McAllister A J
J Dairy Sci. 1984 Oct;67(10):2446-54. doi: 10.3168/jds.S0022-0302(84)81594-5.
Records (1554) from 961 cows continuously housed indoors in two types of barns were analyzed for occurrence and detection of estrus and subsequent reproduction. Variables, percentage of cows observed in estrus by 55 days postpartum, days to first recorded estrus and first service, conception rates, service intervals, days open, and services per conception were analyzed by least squares procedures for year of calving, month of calving, genetic line, barn-type-parity subclasses, and interaction of month by line. A higher percentage of multiparous cows in the tie-stall barn (60%) were observed in estrus by 55 days postpartum than those in the loose-housing barn (50%). Days to first recorded estrus and to first service, 54 and 81, were less for tie-stall cows than for loose-housing cows, 66 and 91. Conception rates at first service and overall conception, 54 and 91%, were higher for tie-stall cows than for loose-housing cows, 42 and 80%. A higher percentage of primiparous cows (69%) was in estrus by 55 days than multiparous cows (55%). Days to first estrus and first service were less for primiparous cows, 47 and 70, than multiparous cows, 60 and 80. Days open were less for primiparous cows. Primiparous cows required 1.9 services per conception compared with 1.7 for multiparous cows.
对961头持续饲养在两种类型牛舍内的奶牛的记录（1554条）进行了分析，以研究发情的发生、检测以及随后的繁殖情况。通过最小二乘法程序，对产犊年份、产犊月份、遗传品系、牛舍类型-胎次亚类以及月份与品系的相互作用，分析了产后55天观察到发情的奶牛百分比、首次记录发情和首次配种的天数、受胎率、配种间隔、空怀天数以及每次受胎的配种次数等变量。与散养牛舍（50%）相比，栓系牛舍中经产奶牛在产后55天观察到发情的比例更高（60%）。栓系牛首次记录发情和首次配种的天数分别为54天和81天，短于散养牛的66天和91天。栓系牛首次配种时的受胎率和总体受胎率分别为54%和91%，高于散养牛的42%和80%。初产奶牛在产后55天发情的比例（69%）高于经产奶牛（55%）。初产奶牛首次发情和首次配种的天数分别为47天和70天，短于经产奶牛的60天和80天。初产奶牛的空怀天数较少。初产奶牛每次受胎需要1.9次配种，而经产奶牛为1.7次。
