Division of Animal Sciences and College of Veterinary Medicine, University of Missouri, Columbia 65211, USA.
J Dairy Sci. 2013 Jun;96(6):3806-16. doi: 10.3168/jds.2012-6474. Epub 2013 Apr 12.
Progesterone-containing controlled internal drug release (CIDR) inserts are used to synchronize the estrous cycle before PGF2α is administered for timed AI (14dCIDR-PGF2α program). The program, initially designed for beef cattle, was recently shown to be efficacious in dairy heifers. We hypothesized that the 14-d CIDR treatment would synchronize the estrous cycle in dairy heifers and result in a uniformly sized corpus luteum (CL) and largest follicle (LF) at the time of PGF2α treatment. Holstein (n=110) or Holstein × Guernsey (n=4) dairy heifers were assigned to 2 treatments: (1) 14dCIDR-PGF2α [CIDR in for 14 d, CIDR out for 16d, PGF2α and AI after observed estrus (n=57)] or (2) control [PGF2α and AI after observed estrus (n=57)]. Regardless of treatment, additional PGF2α injections were administered at 14-d intervals to heifers that were not seen in estrus. Ovarian ultrasonography and blood sampling were done on d 0 (CIDR administered), 14 (day CIDR removed), 19 (5d after CIDR removed), 30 (PGF2α administered), and 44 (second PGF2α dose administered to heifers that were not detected in estrus after the first PGF2α). Compared with control (untreated), more CIDR-treated heifers were categorized as having a small CL (≤ 9.9 mm) and large LF (15.0-19.9 mm) on d 14 (CIDR removal) and, as expected, a greater percentage of CIDR-treated heifers were in estrus during the 5d after the CIDR removal compared with control heifers (75.4 vs. 22.8%, respectively). On d 19, the CIDR-treated heifers had apparently ovulated based on disappearance of LF and appearance of small CL. On d 30 (PGF2α administration), 89% of 14dCIDR-PGF2α heifers had CL that were ≥ 20 mm in diameter compared with 55% for control. Presence of larger CL on d 30 was associated with greater concentrations of plasma progesterone in 14dCIDR-PGF2α compared with control (10.5 ± 0.5 vs. 5.0 ± 0.6 ng/mL, respectively). The percentages of heifers with LF in the smallest category (≤ 9.9 mm) tended to be less (5.3 vs. 16.6%) and the percentage of heifers with LF in the medium-size category (10.0 to 14.9 mm) tended to be greater (84.2 vs. 69.1%) for 14dCIDR-PGF2α versus control, respectively, on d 30. More heifers were detected in estrus within 5d after the first PGF2α (86.0 vs. 56.1%) and conception rate to AI using sexed semen tended to be greater (61.2% vs. 40.6%) for 14dCIDR-PGF2α compared with control (respectively). Treating dairy heifers with a CIDR for 14 d was an effective method to synchronize an estrous cycle before PGF2α was administered.
含孕激素的宫内节育器（CIDR）用于在前列腺素 F2α（PGF2α）用于定时人工授精（14dCIDR-PGF2α 程序）之前同步发情周期。该程序最初是为肉牛设计的，最近已被证明在奶牛小母牛中有效。我们假设 14dCIDR 处理将使奶牛小母牛的发情周期同步，并在 PGF2α 处理时导致黄体（CL）大小均匀且最大卵泡（LF）最大。荷斯坦（n=110）或荷斯坦 × 格恩西（n=4）奶牛小母牛被分配到 2 种处理方法：（1）14dCIDR-PGF2α [CIDR 放置 14d，CIDR 取出 16d，在观察到发情后进行 PGF2α 和人工授精（n=57）]或（2）对照[在观察到发情后进行 PGF2α 和人工授精（n=57）]。无论处理方法如何，在未发情的小母牛中，每 14d 都要额外注射 PGF2α。在 d0（放置 CIDR）、14（CIDR 取出）、19（CIDR 取出后 5d）、30（PGF2α 给药）和 44（第一次 PGF2α 后未发情的小母牛第二次注射 PGF2α）时进行卵巢超声检查和采血。与对照组（未处理）相比，更多的 CIDR 处理小母牛在 d14（CIDR 取出）时被归类为具有较小的 CL（≤9.9mm）和较大的 LF（15.0-19.9mm），并且正如预期的那样，与对照组小母牛相比，更多的 CIDR 处理小母牛在 CIDR 取出后 5d 内发情的比例更高（分别为 75.4%和 22.8%）。在 d19 时，CIDR 处理的小母牛显然已经排卵，因为 LF 消失并且出现了小的 CL。在 d30（PGF2α 给药）时，与对照组相比，14dCIDR-PGF2α 小母牛中有 89%的 CL 直径≥20mm。与对照组相比，14dCIDR-PGF2α 中较大的 CL 在 d30 时与更高的血浆孕酮浓度相关（分别为 10.5±0.5ng/ml 和 5.0±0.6ng/ml）。14dCIDR-PGF2α 组中 LF 处于最小类别（≤9.9mm）的小母牛百分比趋于减少（5.3%比 16.6%），而 LF 处于中等大小类别（10.0-14.9mm）的小母牛百分比趋于增加（84.2%比 69.1%），与对照组相比，在 d30 时，14dCIDR-PGF2α 处理的小母牛中有更多的小母牛在第一次 PGF2α 后 5d 内发情（86.0%比 56.1%），并且使用性控精液进行人工授精的受孕率趋于更高（61.2%比 40.6%），与对照组相比（分别）。用 CIDR 处理奶牛小母牛 14d 是一种有效的方法，可以在 PGF2α 给药前同步发情周期。
