Cabrera E M, Lauber M R, Peralta E M, Bilby T R, Fricke P M
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison 53706.
Merck Animal Health, Kenilworth, NJ 07033.
JDS Commun. 2020 Dec 11;2(1):35-40. doi: 10.3168/jdsc.2020-0024. eCollection 2021 Jan.
Our objective was to assess the effect of treatment with GnRH or 4 increasing doses of human chorionic gonadotropin (hCG) on the ovulatory response of a first-wave dominant follicle and subsequent plasma progesterone (P4) concentrations. Lactating Holstein cows were blocked by parity (primiparous vs. multiparous) and randomly assigned to receive no treatment (control, CON; n = 147), 100 μg of GnRH (n = 144), or 1,000 (n = 138), 2,000 (n = 144), 2,500 (n = 142), or 3,300 (n = 139) IU of hCG 7 d after the last GnRH treatment (G2) of a Double-Ovsynch (DO) or Resynch protocol. Blood samples were collected and ovaries were evaluated with transrectal ultrasonography immediately before treatment and 7 d later to assess serum P4 concentrations and ovulatory response to treatment. Data were analyzed using the MIXED and GLIMMIX procedures of SAS (SAS Institute Inc., Cary, NC). Overall, ovulatory response differed and was 4.8, 79.0, 77.4, 88.9, 92.9, and 95.6% for CON, GnRH, 1,000-, 2,000-, 2,500-, and 3,300-IU hCG treatments, respectively. The increase in plasma P4 concentrations from 7 to 14 d after G2 differed among treatments and was 3.5, 5.9, 5.7, 6.6, 7.0, and 6.5 ng/mL for CON, GnRH, 1,000-, 2,000-, 2,500-, and 3,300-IU hCG treatments, respectively. In conclusion, lactating Holstein cows treated 7 d after G2 with 100 μg of GnRH or 1,000 IU of hCG had similar ovulatory responses (78%), whereas cows treated with 2,000, 2,500, or 3,300 IU of hCG had increased ovulatory responses (92%). Ovulatory response of cows treated with 2,000 or 2,500 IU of hCG did not differ, whereas the ovulatory response after 3,300 IU was greater than that after 2,000 IU of hCG. Plasma P4 concentrations and luteal volume 7 d after treatment were increased compared with those of untreated control cows.
我们的目标是评估促性腺激素释放激素（GnRH）或4种递增剂量的人绒毛膜促性腺激素（hCG）对首波优势卵泡排卵反应及随后血浆孕酮（P4）浓度的影响。将泌乳的荷斯坦奶牛按胎次（初产与经产）进行分组，并随机分配至不接受任何处理（对照组，CON；n = 147）、接受100 μg GnRH（n = 144），或在双同期排卵（DO）或再同期排卵方案的末次GnRH处理（G2）后7天接受1000（n = 138）、2000（n = 144）、2500（n = 142）或3300（n = 139）国际单位（IU）的hCG处理。在处理前及处理后7天采集血样，并通过经直肠超声检查评估卵巢，以测定血清P4浓度及对处理的排卵反应。使用SAS（SAS Institute Inc.，卡里，北卡罗来纳州）的MIXED和GLIMMIX程序对数据进行分析。总体而言，排卵反应存在差异，CON、GnRH、1000-IU、2000-IU、2500-IU和3300-IU hCG处理组的排卵反应分别为4.8%、79.0%、77.4%、88.9%、92.9%和95.6%。G2处理后7至14天血浆P4浓度的升高在各处理组间存在差异，CON、GnRH、1000-IU、2000-IU、2500-IU和3300-IU hCG处理组分别为3.5、5.9、5.7、6.6、7.0和6.5 ng/mL。总之，在G2处理后7天接受100 μg GnRH或1000 IU hCG处理的泌乳荷斯坦奶牛具有相似的排卵反应（约78%），而接受2000、2500或3300 IU hCG处理的奶牛排卵反应增加（约92%）。接受2000或2500 IU hCG处理的奶牛排卵反应无差异，而3300 IU hCG处理后的排卵反应大于2000 IU hCG处理后的排卵反应。与未处理的对照奶牛相比，处理后7天血浆P4浓度和黄体体积增加。
