Kafi Mojtaba, Mirzaei Abdolah
Department of Clinical Science, School of Veterinary Medicine, Shiraz University, Shiraz, 71345, Iran.
Trop Anim Health Prod. 2010 Apr;42(4):761-7. doi: 10.1007/s11250-009-9484-7. Epub 2010 Feb 6.
Seventy multiparous healthy lactating Holstein cows (fat-corrected milk yield = 7,561.8 kg) were monitored from 14 days before to 70 days after calving. Transrectal ultrasound scanning was performed twice weekly from 7 to 65 days postpartum. Blood samples were also collected twice weekly to measure serum P(4) and biweekly to detect serum beta-hydroxybutyrate (betaHB) and nonesterified fatty acid (NEFA) concentrations. Body condition score (BCS) was taken biweekly after calving. Based on the serum P(4) profile of 59 cows (11 cows were excluded due to the occurrence of postpartum diseases) studied, 27 (45.8%) had normal ovarian activity, while 21 (35.6%), six (10.1%), three (5.1%), and two (3.4%) had delayed ovulation (DOV), prolonged luteal phase (PLP), short luteal phase (SLP), and cessation of ovarian activity, respectively. Cows with PLP had an earlier ovulation compared to that of cows with normal ovarian activity (23.16 +/- 4.02 vs 31.9 +/- 8.35 days; P < 0.05). PLP cows also had a greater mean +/- standard deviation peak milk yield (44.2 +/- 5.8 vs 37.2 +/- 5.7 kg/day, 75 days postpartum; P < 0.05) than cows with normal postpartum ovarian activity. The PLP group also had greater milk production in the previous lactation period. Logistic regression analysis indicated that cows with P(4) concentration > or =1 ng/ml on day 24 after calving were more at risk for PLP by 1.1 for each 1 kg increase in mean peak milk yield during 75 days after calving. BCS was lower in cows with DOV compared to that of cows with normal ovarian activity at any time after calving (P < 0.05). Serum betaHB concentrations in DOV cows were significantly higher than that of normal cows on day 42 after calving (0.69 +/- 0.29 vs 0.54 +/- 0.12 mmol/L, P < 0.05). No significant difference was found in the mean concentrations of NEFA between cows in different groups at any time after calving (P > 0.05). The concentrations of P(4) on days 28 and 31 were negatively correlated with betaHB concentration on day 42 after calving in cows with normal ovarian activity (R = -0.44, P = 0.02). In conclusion, these findings suggest that early ovulation and hence early postpartum P(4) rise in addition to the high milk production could partly be responsible for the occurrence of PLP in dairy cows.
70头经产健康泌乳荷斯坦奶牛（校正乳产量 = 7561.8千克）在产犊前14天至产后70天接受监测。产后7至65天每周进行两次经直肠超声扫描。每周采集两次血样以测定血清孕酮（P(4)），每两周采集一次血样以检测血清β-羟丁酸（βHB）和非酯化脂肪酸（NEFA）浓度。产犊后每两周进行一次体况评分（BCS）。根据对59头奶牛（11头因产后疾病而被排除）的血清P(4)曲线研究，27头（45.8%）卵巢活动正常，而21头（35.6%）、6头（10.1%）、3头（5.1%）和2头（3.4%）分别出现排卵延迟（DOV）、黄体期延长（PLP）、黄体期缩短（SLP）和卵巢活动停止。与卵巢活动正常的奶牛相比，PLP奶牛排卵更早（23.16±4.02天对31.9±8.35天；P<0.05）。PLP奶牛在产后75天的平均±标准差峰值产奶量也高于卵巢活动正常的奶牛（44.2±5.8对37.2±5.7千克/天，产后75天；P<0.05）。PLP组在前一个泌乳期的产奶量也更高。逻辑回归分析表明，产犊后第24天P(4)浓度≥1纳克/毫升的奶牛，产后75天平均峰值产奶量每增加1千克，发生PLP的风险增加1.1倍。与卵巢活动正常的奶牛相比，DOV奶牛在产犊后任何时间的BCS都更低（P<0.05）。DOV奶牛在产后第42天的血清βHB浓度显著高于正常奶牛（0.69±0.29对0.54±0.12毫摩尔/升，P<0.05）。产犊后任何时间不同组奶牛的NEFA平均浓度均无显著差异（P>0.05）。卵巢活动正常的奶牛在产后第28天和第31天的P(4)浓度与产后第4天的βHB浓度呈负相关（R = -0.44，P = 0.02）。总之，这些发现表明，早期排卵以及产后早期P(4)升高，再加上高产奶量，可能是奶牛发生PLP的部分原因。
