Lucy M C, Billings H J, Butler W R, Ehnis L R, Fields M J, Kesler D J, Kinder J E, Mattos R C, Short R E, Thatcher W W, Wettemann R P, Yelich J V, Hafs H D
Department of Animal Science, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2001 Apr;79(4):982-95. doi: 10.2527/2001.794982x.
The objective was to test the efficacy of an intravaginal progesterone insert and injection of PGF2alpha for synchronizing estrus and shortening the interval to pregnancy in cattle. Cattle were assigned to one of three treatments before a 31-d breeding period that employed artificial insemination. Control cattle were not treated, and treated cattle were administered PGF2alpha or an intravaginal progesterone-releasing insert (CIDR) for 7 d and treated with PGF2alpha on d 6. The treatments were applied in one of three experiments that involved postpartum beef cows (Exp. 1; n = 851; 56+/-0.6 d postpartum), beef heifers (Exp. 2; n = 724; 442.5+/-2.8 d of age), and dairy heifers (Exp. 3; n = 260; 443.2+/-4.5 d of age). Luteal activity before treatment was determined for individual cattle based on blood progesterone concentrations. In Exp. 1, there was a greater incidence of estrus during the first 3 d of the breeding period in CIDR+PGF2alpha-treated cows compared with PGF2alpha-treated or control cows (15, 33, and 59% for control, PGF2alpha, and CIDR+PGF2alpha, respectively; P < 0.001). The improved estrous response led to an increase in pregnancy rate during the 3-d period (7, 22, and 36% for control, PGF2alpha, and CIDR+PGF2alpha, respectively; P < 0.001) and tended to improve pregnancy rate for the 31-d breeding period for cows treated with CIDR+PGF2alpha, (50, 55, and 58% for control, PGF2alpha, and CIDR+PGF2alpha, respectively, P = 0.10). Improvements in rates of estrus and pregnancy after CIDR+PGF2alpha, were also observed in beef heifers. Presence of luteal activity before the treatment period affected synchronization and pregnancy rates because anestrous cows (Exp. 1) or prepubertal heifers (Exp. 2) had lesser synchronization rates and pregnancy rates during the first 3 d of the breeding period as well as during the entire 31-d breeding period. The PGF2alpha, and CIDR+PGF2alpha but not the control treatments were evaluated in dairy heifers (Exp. 3). The CIDR+PGF2alpha-treated heifers had a greater incidence of estrus (84%) during the first 3 d of the breeding period compared with the PGF2alpha-treated heifers (57%), but pregnancy rates during the first 3 d or during the 31-d breeding period were not improved for CIDR+PGF2alpha compared with PGF2alpha-treated heifers. In summary, the concurrent treatment of CIDR and PGF2alpha improved synchronization rates relative to PGF2alpha alone or control. Improved estrus synchrony led to greater pregnancy rates for beef cows and beef heifers but failed to improve pregnancy rates for dairy heifers.
目的是测试阴道内植入孕酮和注射前列腺素F2α对牛发情同步化及缩短怀孕间隔时间的效果。在为期31天的人工授精繁殖期之前，将牛分为三种处理组之一。对照组牛不进行处理，处理组牛接受7天的前列腺素F2α或阴道内释放孕酮的植入物（CIDR）处理，并在第6天用前列腺素F2α处理。这些处理应用于三个实验之一，实验对象包括产后肉牛母牛（实验1；n = 851；产后56±0.6天）、肉牛小母牛（实验2；n = 724；年龄442.5±2.8天）和奶牛小母牛（实验3；n = 260；年龄443.2±4.5天）。根据个体牛的血液孕酮浓度确定处理前的黄体活性。在实验1中，与前列腺素F2α处理组或对照组母牛相比，CIDR + 前列腺素F2α处理的母牛在繁殖期的前3天发情发生率更高（对照组、前列腺素F2α组和CIDR + 前列腺素F2α组分别为5%、33%和59%；P < 0.001）。发情反应的改善导致3天内怀孕率增加（对照组、前列腺素F2α组和CIDR + 前列腺素F2α组分别为7%、22%和36%；P < 0.001），并且CIDR + 前列腺素F2α处理的母牛在31天繁殖期的怀孕率有提高的趋势（对照组、前列腺素F2α组和CIDR + 前列腺素F2α组分别为50%、55%和58%，P = 0.10）。在肉牛小母牛中也观察到CIDR + 前列腺素F2α处理后发情率和怀孕率的提高。处理期前黄体活性的存在影响同步化和怀孕率，因为处于乏情期的母牛（实验1）或青春期前小母牛（实验2）在繁殖期的前3天以及整个31天繁殖期的同步化率和怀孕率较低。在奶牛小母牛（实验3）中评估了前列腺素F2α和CIDR + 前列腺素F2α处理组，但未评估对照组。与前列腺素F2α处理的小母牛（57%）相比，CIDR + 前列腺素F2α处理的小母牛在繁殖期的前3天发情发生率更高（84%），但与前列腺素F2α处理的小母牛相比，CIDR + 前列腺素F2α处理的小母牛在3天内或31天繁殖期的怀孕率并未提高。总之，与单独使用前列腺素F2α或对照组相比，CIDR和前列腺素F2α的联合处理提高了同步化率。发情同步化的改善导致肉牛母牛和肉牛小母牛的怀孕率更高，但未能提高奶牛小母牛的怀孕率。
