Nation D P, Burke C R, Parton G, Stevenson R, Macmillan K L
Dairying Research Corporation (Ltd), Private Bag 3123, Hamilton, New Zealand.
Anim Reprod Sci. 2000 Oct 2;63(1-2):13-25. doi: 10.1016/s0378-4320(00)00164-0.
Primiparous cows with low body condition at calving have an extended anovulatory period. Induction of ovulation and oestrus is possible with progesterone treatment but the response to this treatment differs between Friesian and Jersey breeds. The objective of this study was to describe changes in pulsatile LH secretion and the synchrony of developing ovarian follicles that occur during a progesterone treatment period of 5 days in primiparous anovulatory cows. The experimental model compared the progesterone treatment with spontaneous post-partum changes as well as a breed comparison in a factorial design.Thirty-six cows (Jersey n=19 and Friesian n=17) were managed to calve with a low body condition score (BCS<4. 5). Daily changes in ovarian follicle size were observed with transrectal ultrasonography in each cow from 8 days post-partum. Thirty of these cows were diagnosed to be anovulatory at 12-18 days post-partum (day 0) and allocated to a treatment (n=16) or a control group (n=14), balanced for breed. Each treated cow had a progesterone-releasing controlled internal drug-releasing (CIDR) device inserted vaginally for 5 days while control cows were left untreated. Changes in plasma LH concentrations were measured with intensive blood sampling over 8 h on days -1, 1, and 4. Blood samples were also collected daily (06:00 h) for determination of plasma progesterone as well as oestradiol concentrations on days 6 and 8. Treatment with progesterone was associated with a transient initial decrease (day 1) in both LH pulse frequency and mean LH concentrations after device insertion, but both had returned to pre-treatment levels by day 4. Jersey cows had a greater pulse frequency, but there was no breed difference in mean LH concentrations. Patterns of ovarian follicle growth were affected by progesterone treatment with an increase in diameter of the dominant follicle (DF) identified after treatment initiation. This followed an earlier emergence of a new DF after device insertion. Follicular response to progesterone was dependent on the diameter of the DF present at treatment initiation. Those follicles >/=9 mm were replaced by a new DF during treatment such that the DF observed at the time of device removal was large (>/=9 mm) and growing in 13/16 cases.Progesterone was not effective for the induction of an LH surge, ovulation and oestrus in anovulatory cows with a low BCS. However, treatment was associated with synchronous development of a DF so that it was large and growing at the end of the treatment period in most cases. This synchronous development may be due to the transient suppression of LH and the presence of an LH-dependent DF.
产犊时体况较差的初产母牛无排卵期会延长。用孕酮治疗可诱导排卵和发情，但弗里斯兰牛和泽西牛对这种治疗的反应有所不同。本研究的目的是描述初产无排卵母牛在5天孕酮治疗期内促黄体生成素（LH）脉冲式分泌的变化以及发育中的卵巢卵泡的同步性。实验模型采用析因设计，将孕酮治疗与产后自发变化以及品种比较进行了对比。36头母牛（泽西牛19头，弗里斯兰牛17头）被管理至以低体况评分（BCS<4.5）产犊。从产后8天起，通过经直肠超声检查观察每头母牛卵巢卵泡大小的每日变化。其中30头母牛在产后12 - 18天（第0天）被诊断为无排卵，并分配到治疗组（n = 16）或对照组（n = 14），两组在品种上保持平衡。每头接受治疗的母牛阴道内插入一个释放孕酮的可控内部药物释放（CIDR）装置，持续5天，而对照组母牛不进行治疗。在第 - 1天、第1天和第4天，通过密集采血8小时来测量血浆LH浓度的变化。在第6天和第8天，每天（06:00 h）采集血样，用于测定血浆孕酮以及雌二醇浓度。孕酮治疗与装置插入后LH脉冲频率和平均LH浓度的短暂初始下降（第1天）有关，但到第4天两者均恢复到治疗前水平。泽西牛的脉冲频率更高，但平均LH浓度在品种间无差异。卵巢卵泡生长模式受孕酮治疗影响，治疗开始后优势卵泡（DF）直径增加。这是在装置插入后新的DF更早出现之后发生的。卵泡对孕酮的反应取决于治疗开始时存在的DF直径。那些直径≥9 mm的卵泡在治疗期间被新的DF取代，以至于在装置取出时观察到的DF很大（≥9 mm），并且在16例中有13例在生长。孕酮对低BCS的无排卵母牛诱导LH峰、排卵和发情无效。然而，治疗与DF的同步发育有关，因此在大多数情况下，在治疗期结束时DF很大且在生长。这种同步发育可能是由于LH的短暂抑制以及存在依赖LH的DF。
