上一胎哺乳期受孕天数对产犊前后死亡和活淘汰风险的影响。

Effect of days to conception in the previous lactation on the risk of death and live culling around calving.

机构信息

Department of Animal Sciences, University of Florida, Gainesville 32611, USA.

出版信息

J Dairy Sci. 2010 Mar;93(3):968-77. doi: 10.3168/jds.2009-2408.

DOI:10.3168/jds.2009-2408

PMID:20172217

Abstract

The objective was to quantify the effect of days to conception (days open) in the previous parity on the risk of death and live culling (excluding the disposal reasons "dairy purposes" and "death") in the proximity of a subsequent calving in Holstein cows enrolled in the Dairy Herd Improvement program. After edits, 2,075,834 observations of cows calving between 2001 and 2007 in herds located in 36 US states primarily east of the Mississippi river were available. The period at risk included the time between 14 d before expected calving to 60 d after calving. Days open were categorized in 6 periods: 0 to 45 d, 46 to 90 d, 91 to 150 d, 151 to 210 d, 211 to 300 d, and 301 to 600 d after calving in the previous parity. Other variables of interest included parity, length of the dry period before calving, relative last test-day milk yield before dry off before calving, season of calving, and the cow's relative 305-d mature equivalent (305ME) milk yield before calving. Control variables were calving year, herd size, and relative herd 305ME milk yield. All variables were categorized. Generalized mixed models were used and included herd as random effect. Interactions between days open and the variables of interest were included in the models. Least squares means for the risk of death between -14 and 60 d after calving were 2.5, 2.5, 2.9, 3.6, 4.4, and 5.8% for increasing categories of days open. Similarly, for the same categories, least squares means for the risk of live culling were 4.5, 5.0, 5.4, 6.1, 6.9, and 8.1%. The effect of days open on the risk of death was slightly greater for third-parity cows, for long dry periods, for cows with low test-day milk yield before dry off before calving, for spring calvings, and for intermediate relative 305ME milk yield before calving. Similar trends for these interactions were found for the risk of live culling, except for relative 305ME milk yield before calving, where the effect of days open was more pronounced for high-producing cows. In conclusion, increased days open in the previous parity were associated with a greater risk of death and live culling around calving.

摘要

目的是量化前一胎的配种天数（开放天数）对荷斯坦奶牛在后续产犊临近时死亡和活淘汰（不包括“乳业用途”和“死亡”处置原因）的风险的影响。在编辑后，2001 年至 2007 年间在美国 36 个州的奶牛场登记的奶牛中有 2075834 次产犊观察结果可用。风险期包括预计产犊前 14 天至产犊后 60 天之间的时间。开放天数分为 6 个时期：产犊后 0 至 45 天、46 至 90 天、91 至 150 天、151 至 210 天、211 至 300 天和 301 至 600 天。其他感兴趣的变量包括胎次、产犊前干奶期的长度、产犊前干奶前最后一次测试日的相对牛奶产量、产犊季节和奶牛产犊前相对 305 天成熟当量（305ME）牛奶产量。控制变量包括产犊年份、牛群规模和相对牛群 305ME 牛奶产量。所有变量均分类。使用广义混合模型，并将牛群作为随机效应。模型中包含了开放天数与感兴趣变量之间的交互作用。产犊后-14 天至 60 天之间死亡风险的最小二乘均值分别为 2.5%、2.5%、2.9%、3.6%、4.4%和 5.8%，与开放天数增加的类别相对应。同样，对于相同的类别，产犊后-14 天至 60 天之间活淘汰的最小二乘均值分别为 4.5%、5.0%、5.4%、6.1%、6.9%和 8.1%。开放天数对第三胎奶牛、干奶期长、产犊前最后一次测试日牛奶产量低、春季产犊和产犊前相对 305ME 牛奶产量中等的奶牛死亡风险的影响略大。对于活淘汰的风险，也发现了这些交互作用的相似趋势，但产犊前相对 305ME 牛奶产量除外，其中开放天数对高产量奶牛的影响更为显著。总之，前一胎的开放天数增加与产犊前后的死亡和活淘汰风险增加有关。