Mezera M A, Lauber M R, Beard A D, Cabrera E M, Wiltbank M C, Fricke P M
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison 53706.
Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison 53706.
JDS Commun. 2021 Sep 13;2(6):421-425. doi: 10.3168/jdsc.2021-0142. eCollection 2021 Nov.
Lutalyse HighCon (dinoprost tromethamine; Zoetis) has been approved for use both intramuscularly and subcutaneously in lactating dairy cows, although the effect of route of administration on circulating 13,14-dihydro-15-keto-prostaglandin F (PGFM), the metabolite of PGF, has not been evaluated. Multiparous, lactating Holstein cows were submitted to an Ovsynch protocol in which the last GnRH treatment (G2) was designated as d 0. Cows were fitted with indwelling jugular catheters on d 6 and administered 25 mg of dinoprost tromethamine (2 mL of Lutalyse HighCon) on d 7 either subcutaneously in the neck (SC; n = 6) or intramuscularly in the semitendinosus muscle (IM; n = 6). Blood samples were collected every 15 min after treatment for 1.75 h, then every 2 h for 48 h, and at 60 and 72 h, with the last time point corresponding to when cows would have received timed AI at 72 h within an Ovsynch protocol. Circulating PGFM concentrations were greater for SC than for IM cows from 15 to 90 min after treatment, which resulted in a greater area under the PGFM curve during the first 90 min after treatment (means ± SEM; 1,664 ± 129 pg·h/mL vs. 1,146 ± 177 pg·h/mL for SC vs. IM cows, respectively). This resulted in complete luteolysis in all but one cow in the SC treatment at 56 h, when GnRH would have been administered if dinoprost tromethamine had been administered as part of an Ovsynch protocol for timed AI. For cows that underwent complete luteal regression, circulating P4 did not differ between treatments at any time point. Thus, although SC cows had increased circulating PGFM 15 to 90 min after treatment, there was no difference in circulating P4 during induced luteolysis based on route of dinoprost tromethamine administration.
Lutalyse HighCon（氯前列醇钠；硕腾公司）已被批准用于泌乳奶牛的肌肉注射和皮下注射，尽管尚未评估给药途径对循环中的13,14 - 二氢 - 15 - 酮 - 前列腺素F（PGFM）（PGF的代谢产物）的影响。经产泌乳荷斯坦奶牛接受了Ovsynch方案，其中最后一次促性腺激素释放激素（GnRH）处理（G2）被指定为第0天。奶牛在第6天安装了颈静脉留置导管，并在第7天给予25 mg氯前列醇钠（2 mL Lutalyse HighCon），分别通过颈部皮下注射（SC；n = 6）或半腱肌肌肉注射（IM；n = 6）。处理后每15分钟采集一次血样，持续1.75小时，然后每2小时采集一次，持续48小时，并在60和72小时采集，最后一个时间点对应于奶牛在Ovsynch方案中72小时接受定时人工授精的时间。处理后15至90分钟，SC组奶牛的循环PGFM浓度高于IM组奶牛，这导致处理后前90分钟内PGFM曲线下面积更大（平均值±标准误；SC组奶牛为1,664±129 pg·h/mL，IM组奶牛为1,146±177 pg·h/mL）。这导致SC组除一头奶牛外的所有奶牛在56小时时完全黄体溶解，如果氯前列醇钠作为定时人工授精的Ovsynch方案的一部分给药，此时应给予GnRH。对于经历完全黄体退化的奶牛，各处理组在任何时间点的循环孕酮（P4）均无差异。因此，尽管SC组奶牛在处理后15至90分钟循环PGFM增加，但基于氯前列醇钠的给药途径，诱导黄体溶解期间循环P4并无差异。
