Galvão K N, Frajblat M, Butler W R, Brittin S B, Guard C L, Gilbert R O
Department of Clinical Sciences, Cornell University, Ithaca, NY 14853-6401, USA.
Reprod Domest Anim. 2010 Oct;45(5):e207-11. doi: 10.1111/j.1439-0531.2009.01517.x.
Our objectives were to determine the effects of early ovulation on fertility and uterine health of dairy cows. Four hundred and forty-five Holstein cows (185 primiparous and 260 multiparous) from five herds were used. Blood samples were collected at 21, 35 and 49 days in milk (DIM) and cows were considered to be cyclic at 21 DIM (Cyc21) if serum progesterone (P4) concentration was above 1 ng/ml, cyclic by 49 DIM (Cyc49) if P4 concentration was above 1 ng/ml at 35 or 49 DIM, or not cyclic (NotCyc) if P4 concentration was below 1 ng/ml at all sample times. Endometrial cytology for diagnosis of subclinical endometritis was examined at 49 DIM in a subset of 414 cows. Cows in the group Cyc21 had increased hazard of insemination, for the first service, compared with cows in Cyc49 [hazard ratio (HR) = 1.40; 95% CI = 1.10-1.79; p = 0.006] and NotCyc (HR = 2.07; 95% CI = 1.52-2.82; p < 0.001). Cows in the Cyc49 group also had increased hazard of insemination compared with cows in the NotCyc group (HR = 1.47; 95% CI = 1.13-1.93; p = 0.005). Median days to insemination were, respectively, 71, 76 and 96 for cows in Cyc21, Cyc49 and NotCyc groups. Cows in Cyc21 had greater first service pregnancy per AI than Cyc49 [38.6 vs 28.1%; adjusted odds ratio (AOR) = 1.67; 95% CI = 1.01-2.75; p = 0.04] and NotCyc (38.6 vs 23.6%; AOR = 2.08; 95% CI = 1.08-4.00; p = 0.03). Pregnancy per AI was similar in Cyc49 and NotCyc cows (28.1 vs 23.6%; AOR = 1.25; 95% CI = 0.70-2.24; p = 0.45). Cows in Cyc21 had increased hazard of pregnancy up to 300 DIM compared with Cyc49 (HR = 1.52; 95% CI = 1.17-1.96; p = 0.002) and NotCyc (HR = 1.98; 95% CI = 1.41-2.78; p < 0.001). Cows in Cyc49 tended to have increased hazard of pregnancy compared with NotCyc (HR = 1.31; 95% CI = 0.96-1.77; p = 0.09). Median days to pregnancy were, respectively, 103, 147 and 173 for cows in Cyc21, Cyc49 and NotCyc groups. Cows in the Cyc21 group had decreased prevalence of subclinical endometritis compared with cows in the NotCyc group (29.9 vs 43.7%; AOR = 0.53; 95% CI = 0.29-0.97; p = 0.04); however, the prevalence did not differ from the Cyc49 group (29.9 vs 39.1%; AOR = 0.68; 95% CI = 0.41-1.14; p = 0.15). Cyc49 cows had similar prevalence of subclinical endometritis compared with NotCyc cows (AOR = 0.77; 95% CI = 0.46-1.29; p = 0.32). Early postpartum ovulation was associated with improved uterine health and fertility.
我们的目标是确定早期排卵对奶牛繁殖力和子宫健康的影响。使用了来自五个牛群的445头荷斯坦奶牛（185头初产牛和260头经产牛）。在产奶21天、35天和49天时采集血样，如果血清孕酮（P4）浓度高于1 ng/ml，则奶牛在21天产奶时被认为处于发情周期（Cyc21）；如果在35天或49天产奶时P4浓度高于1 ng/ml，则在49天产奶时处于发情周期（Cyc49）；如果在所有采样时间P4浓度均低于1 ng/ml，则为非发情周期（NotCyc）。在414头奶牛的子集中，于49天产奶时检查子宫内膜细胞学以诊断亚临床子宫内膜炎。与Cyc49组奶牛相比，Cyc21组奶牛首次输精的风险增加[风险比（HR）= 1.40；95%置信区间（CI）= 1.10 - 1.79；p = 0.006]，与NotCyc组相比风险更高（HR = 2.07；95% CI = 1.52 - 2.82；p < 0.001）。与NotCyc组奶牛相比，Cyc49组奶牛输精的风险也增加（HR = 1.47；95% CI = 1.13 - 1.93；p = 0.005）。Cyc21组、Cyc49组和NotCyc组奶牛首次输精的中位天数分别为71天、76天和96天。与Cyc49组相比，Cyc21组奶牛每次人工授精后的首次妊娠率更高[38.6%对28.1%；调整优势比（AOR）= 1.67；95% CI = 1.01 - 2.75；p = 0.04]，与NotCyc组相比也更高（38.6%对23.6%；AOR = 2.08；95% CI = 1.08 - 4.00；p = 0.0
