Abstract：
The objective of this observational study was to evaluate the association between increased physical activity at first artificial insemination (AI) and subsequent pregnancy per AI (P/AI) in lactating Holstein cows following spontaneous estrus or a timed AI (TAI) protocol. We also wanted to identify factors associated with the intensity of activity increase (PA) captured by automated activity monitors (AAM) and fertility. Two experiments were conducted, in which cows either were inseminated based on the alert of the AAM system (AAM cows) or received TAI following a 7-d Ovsynch protocol (TAI cows) if not inseminated within a farm-specific period after calving. Experiment 1 included 2,698 AI services from AAM cows and 1,042 AI services from TAI cows equipped with the Smarttag Neck (Nedap Livestock Management) from a dairy farm in Slovakia (farm 1). In the second experiment, 6,517 AI services from AAM cows and 1,226 AI services from TAI cows fitted with Heatime (Heatime Pro; SCR Engineers Ltd.) from 8 dairy farms in Germany (farms 2-9) were included. Pregnancy diagnosis was performed on a weekly basis by transrectal ultrasound (farms 1, 3, 7, 8) or by transrectal palpation (farms 2, 4-6, 9). Estrous intensity was represented by the peak value of the change in activity. In experiment 1, PA was categorized into low (x-factor 0-20) and high (x-factor 21-100) PA, and in experiment 2 into low (activity change = 35-89) and high (activity change = 90-100) PA. In TAI cows from both experiments, PA was additionally categorized into cows with no AAM alert. Data were analyzed separately for AAM and TAI cows using multinomial logistic regression models for PA in TAI cows and logistic regression models for PA in AAM cows and P/AI in both groups. In experiment 1, P/AI of AAM cows was greater for AI services performed with conventional frozen semen (57.6%) compared with sexed semen (47.2%), whereas type of semen only tended to be associated with P/AI in TAI cows (54.4% conventional frozen semen vs. 48.9% sexed semen). In experiment 2, P/AI was greater for fresh semen (AAM cows: 44.4% vs. TAI cows: 44.2%) compared with conventional frozen semen (AAM cows: 37.6% vs. TAI cows: 34.6%). In both experiments, pregnancy outcomes were associated with PA. In experiment 1, AAM cows with high PA (55.1%) had greater P/AI than cows with low PA (49.8%). Within TAI cows, cows with no alert (38.8%) had reduced P/AI compared with cows with low (54.2%) or high PA (61.8%). In experiment 2, AAM cows with high PA (45.8%) had greater P/AI compared with cows with low PA (36.4%). Timed AI cows with no alert (27.4%) had decreased P/AI compared with cows with low (41.1%) or high (50.8%) PA. The greatest risk factors for high PA were parity (experiment 1) and season of AI (except for TAI cows from experiment 1). We conclude that high PA at the time of AI is associated with greater odds of pregnancy for both AAM and TAI cows. In both experiments, about 2 thirds of AAM cows (experiment 1: 69.9% and experiment 2: 70.7%) reached high PA, whereas only approximately one-third or less of TAI cows (experiment 1: 37.3% and experiment 2: 23.6%) showed high PA. Although we observed similar results using 2 different AAM systems for the most part, risk factors for high PA might differ between farms and insemination type (i.e., AAM vs. TAI).
摘要：
这项观察性研究的目的是评估首次人工授精（AI）时增加的体力活动与自发发情或定时AI（TAI）方案后泌乳荷斯坦奶牛的每次AI（P/AI）随后怀孕之间的关联。我们还想确定与自动活动监测器（AAM）和生育力捕获的活动强度增加（PA）相关的因素。进行了两个实验，其中母牛要么根据AAM系统的警报进行授精（AAM母牛），要么根据7dOvsynch协议（TAI母牛）接受TAI，如果未在产牛后的特定农场时期内授精。实验1包括来自AAM奶牛的2,698个AI服务和来自TAI奶牛的1,042个AI服务，这些奶牛配备了SmarttagNeck（Nedap牲畜管理），来自斯洛伐克的一家奶牛场（农场1）。在第二个实验中,包括来自德国8个奶牛场（2-9个农场）的AAM奶牛的6,517个AI服务和TAI奶牛的1,226个AI服务。每周通过经直肠超声（农场1、3、7、8）或经直肠触诊（农场2、4-6、9）进行妊娠诊断。发情强度由活性变化的峰值表示。在实验1中，PA分为低（x因子0-20）和高（x因子21-100）PA，在实验2中分为低（活性变化=35-89）和高（活性变化=90-100）PA。在两个实验的TAI奶牛中，PA被另外分类为没有AAM警报的奶牛。使用TAI奶牛中PA的多项逻辑回归模型和AAM奶牛中PA和两组P/AI的逻辑回归模型分别分析AAM和TAI奶牛的数据。在实验1中，与性别精液（47.2％）相比，使用常规冷冻精液进行AI服务的AAM母牛的P/AI更大（57.6％），而在TAI奶牛中，精液类型仅倾向于与P/AI相关(54.4%常规冷冻精液与48.9％的精液性别）。在实验2中，新鲜精液的P/AI更高（AAM奶牛：44.4%TAI奶牛：44.2%）与常规冷冻精液相比（AAM奶牛：37.6%与TAI奶牛：34.6%）。在这两个实验中,妊娠结局与PA相关.在实验1中,具有高PA(55.1%)的AAM母牛比具有低PA(49.8%)的母牛具有更大的P/AI。在TAI奶牛中，与低PA(54.2%)或高PA(61.8%)的奶牛相比,无警报(38.8%)的奶牛P/AI降低.在实验2中,与具有低PA(36.4%)的母牛相比,具有高PA(45.8%)的AAM母牛具有更大的P/AI。与低PA（41.1％）或高PA（50.8％）的奶牛相比，无警报的定时AI奶牛（27.4％）的P/AI降低。高PA的最大危险因素是胎次（实验1）和AI季节（实验1的TAI奶牛除外）。我们得出的结论是，AI时的高PA与AAM和TAI奶牛的怀孕几率更大有关。在这两个实验中,大约三分之二的AAM奶牛(实验1:69.9%和实验2:70.7%)达到了高PA，而只有大约三分之一或更少的TAI母牛(实验1:37.3%和实验2:23.6%)显示高PA。尽管我们在大多数情况下使用2种不同的AAM系统观察到类似的结果，高PA的风险因素可能在农场和授精类型之间有所不同(即，AAMvs.TAI).
