Applied Animal Biology, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Applied Animal Biology, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Animal Production, São Paulo State University, Botucatu, SP 18168-000, Brazil.
J Dairy Sci. 2017 Oct;100(10):8484-8495. doi: 10.3168/jds.2016-12160. Epub 2017 Aug 10.
Objectives were to quantify lying behavior (LB) during an estradiol and progesterone-based synchronization protocol, to assess risk factors for ovulation, pregnancy per AI (P/AI), and degree of behavioral change at estrus, and to investigate the associations between estrus LB and walking activity. Holstein cows (43.6 ± 11.0 kg of milk/d) were fitted with leg-mounted accelerometers. Total lying time/d (L_time), bout frequency (bout_N), average lying bout duration, and relative increase in walking activity (ACT%) were evaluated for 1,411 timed artificial insemination events. The day with lowest L_time or bout_N among d -2, -1, and 0 (day of timed artificial insemination) determined the day of behavioral estrus. The variables L_time% and bout_N% represent relative ratios between lowest L_time and baseline (d -7), L_time, and lowest bout_N, and baseline (d -7) bout_N, respectively [e.g., (lowest L_time/baseline L_time) × 100]. Correlation coefficients between L_time% and bout_N% and ACT% were -0.38 and -0.31, respectively. Estrus LB change was considered large if <75% of baseline and small if ≥75% of baseline for both L_time% and bout_N%; average lying bout duration did not change with estrus. Lowest L_time% and bout_N% corresponded to, respectively, 65 ± 21% (mean ± standard deviation; 447 ± 157 min/d) and 65 ± 24% (8.5 ± 4.0 bouts/d) of baseline. The change in L_time% at estrus was smaller when cows had milk yield above average; the change in bout_N% was smaller among multiparous cows and for estrus occurring in the colder season. Likelihood of ovulation was greater when there was larger change in L_time% [odds ratio = 4.9; ovulation rate = 93 (large change) and 76% (small change)], as well as when a corpus luteum was present at start of protocol (odds ratio = 3.6; in the model with L_time%). Likelihood of pregnancy at d 32 was 1.6 times greater for estrus with large change in LB [L_time% or bout_N%; P/AI = 34% (large change in L_time%) and 26% (small change in L_time%)]. Among estrus events with ACT% ≥300% (high intensity), classification by small or large L_time% did not influence P/AI at 32 d. The magnitude of LB change at estrus and its association with fertility suggest potential application toward improved use of activity monitors (e.g., increased estrus detection, fertility prediction). The contribution of LB to accuracy of estrus detection when physical activity is known remains to be addressed. The relationship between intensity of estrus expression and fertility requires further investigations of its physiological rationale and on-farm applications.
目的是在基于雌二醇和孕酮的同步方案中量化说谎行为(LB),评估排卵、人工授精妊娠率(P/AI)的风险因素以及发情期行为变化的程度,并研究发情期 LB 与行走活动之间的关联。荷斯坦奶牛(平均产奶量为 43.6 ± 11.0kg/d)佩戴腿部加速度计。评估了 1411 次定时人工授精事件的总卧床时间/d(L_time)、小睡频率(bout_N)、平均卧床持续时间和行走活动的相对增加(ACT%)。在-2、-1 和 0 天(定时人工授精日)中最低 L_time 或 bout_N 的那一天确定发情行为日。变量 L_time%和 bout_N%分别代表最低 L_time 与基线(-7 天)、L_time 和最低 bout_N 与基线(-7 天)之间的相对比值[例如,(最低 L_time/基线 L_time)×100]。L_time%和 bout_N%与 ACT%之间的相关系数分别为-0.38 和-0.31。如果 L_time%和 bout_N%的基线分别低于 75%和 75%,则认为发情期 LB 变化较大;平均卧床时间没有随发情期而变化。最低 L_time%和 bout_N%分别对应于基线的 65 ± 21%(平均值±标准偏差;447 ± 157min/d)和 65 ± 24%(8.5 ± 4.0 次/d)。当奶牛产奶量高于平均水平时,发情期 L_time%的变化较小;在多胎奶牛中,发情发生在较冷的季节时,bout_N%的变化较小。当 L_time%变化较大时,排卵的可能性更大[比值比=4.9;排卵率=93(大变化)和 76%(小变化)],并且在方案开始时存在黄体时也是如此[比值比=3.6;在有 L_time%的模型中]。发情时 LB 变化较大,妊娠率在第 32 天时增加 1.6 倍[L_time%或 bout_N%;P/AI=34%(L_time%变化大)和 26%(L_time%变化小)]。在 ACT%≥300%(高强度)的发情事件中,根据小或大 L_time%进行分类不会影响 32 天时的 P/AI。发情期 LB 变化的幅度及其与生育力的关系表明,其在活动监测器的改进应用方面具有潜在的应用前景(例如,增加发情检测、预测生育力)。仍需要解决 LB 对已知身体活动的发情检测准确性的贡献。发情表达强度与生育力之间的关系需要进一步研究其生理原理和农场应用。