Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, SP 18618-000, Brazil.
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2017 Oct;100(10):8455-8470. doi: 10.3168/jds.2016-12145. Epub 2017 Aug 2.
Two treatments designed to increase circulating progesterone concentration (P4) during preovulatory follicle development were compared. One treatment used 2 intravaginal P4 implants (controlled internal drug-releasing inserts; CIDR) and the other used a GnRH treatment at beginning of the protocol. Lactating Holstein cows that had been diagnosed as nonpregnant were randomly assigned to receive timed artificial insemination (TAI) following 1 of 2 treatments (n = 1,638 breedings): (1) GnRH: CIDR+ 2 mg of estradiol (E2) benzoate + 100 µg of GnRH on d -11, PGF on d -4, CIDR withdrawal + 1.0 mg of E2-cypionate + PGF) on d -2, and TAI on d 0; or (2) 2CIDR: 2 CIDR + 2 mg of E2-benzoate on d -11, 1 CIDR withdrawn + PGF on d -4, second CIDR withdrawn + 1.0 mg of E2-cypionate + PGF on d -2, and TAI on d 0. Milk yield was measured daily between d 0 and d 7. Rectal temperature was measured using a digital thermometer at d 0 and 7, and elevated body temperature was defined as an average rectal temperature ≥39.1°C. Pregnancy diagnoses were performed on d 32 and 60 after TAI. We detected no effect of treatments on pregnancy per AI or pregnancy loss regardless of elevated body temperature, body condition score, parity, milk yield, or presence or absence of a corpus luteum (CL) on d -11 or d -4. Pregnancy per AI at 60 d was reduced [elevated body temperature = 22.8% (162/709), no elevated body temperature 34.1% (279/817)] and pregnancy loss tended to increase [elevated body temperature = 20.2% (41/203), no elevated body temperature 14.4% (47/326)] in cows with elevated body temperature. Various physiological measurements associated with greater fertility were also reduced in cows with elevated body temperature, such as percentage of cows with a CL at PGF (decreased 7.9%), ovulatory follicle diameter (decreased 0.51 mm), expression of estrus (decreased 5.1%), and ovulation near TAI (decreased 2.8%) compared with cows without elevated body temperature. A greater proportion of cows (30.2%) had a CL at PGF in the GnRH treatment [74.1% (570/763)] than in the 2CIDR treatment [56.9% (434/763)]; however, circulating P4 concentration was greater at the time of PGF treatment (d -4) for cows 2CIDR (4.26 ± 0.13 ng/mL) than in cows in GnRH (3.99 ± 0.14 ng/mL). Thus, these 2 protocols yield similar fertility results that might be due to somewhat different physiological alterations. Treatment with GnRH increased the proportion of cows with a CL at PGF; however, the 2CIDR protocol increased circulating P4 under all circumstances.
两种旨在增加排卵前卵泡发育过程中循环孕酮浓度（P4）的治疗方法进行了比较。一种治疗方法使用 2 个阴道内 P4 植入物（控释内部药物释放插入物；CIDR），另一种治疗方法在方案开始时使用 GnRH 治疗。已被诊断为未怀孕的泌乳荷斯坦奶牛被随机分配接受定时人工授精（TAI），以下 2 种治疗方法之一（n = 1,638 次配种）：（1） GnRH：CIDR+2 mg 苯甲酸雌二醇（E2）+100 µg GnRH 于 d-11，PGF 于 d-4，CIDR 撤回+1.0 mg E2-环戊丙酸酯+PGF 于 d-2，TAI 于 d 0；或（2）2CIDR：2 CIDR+2 mg E2-苯甲酸酯于 d-11，1 CIDR 撤回+PGF 于 d-4，第二 CIDR 撤回+1.0 mg E2-环戊丙酸酯+PGF 于 d-2，TAI 于 d 0。在 d 0 至 d 7 之间每天测量牛奶产量。在 d 0 和 7 使用数字温度计测量直肠温度，并将体温升高定义为平均直肠温度≥39.1°C。在 TAI 后 32 和 60 天进行妊娠诊断。无论体温升高、体况评分、胎次、产奶量或 d-11 或 d-4 是否存在黄体（CL），我们都没有检测到治疗方法对每一次人工授精的妊娠或妊娠损失有影响。60 d 的妊娠率降低[体温升高=22.8%（162/709），体温不升高=34.1%（279/817）]，妊娠损失有增加的趋势[体温升高=20.2%（41/203），体温不升高=14.4%（47/326）]体温升高的奶牛。体温升高的奶牛也降低了与更高生育力相关的各种生理测量值，例如 PGF 时具有 CL 的奶牛百分比（降低了 7.9%）、排卵卵泡直径（降低了 0.51 毫米）、发情表达（降低了 5.1%）和排卵接近 TAI（降低了 2.8%）与没有体温升高的奶牛相比。与 GnRH 治疗相比，更多的奶牛（30.2%）在 PGF 时具有 CL [74.1%（570/763）]，而 2CIDR 治疗为 56.9%（434/763）；然而，在 PGF 治疗（d-4）时，2CIDR 治疗的奶牛循环 P4 浓度更高（4.26±0.13ng/mL），而 GnRH 治疗的奶牛为 3.99±0.14ng/mL。因此，这两种方案产生相似的生育结果，这可能是由于略有不同的生理变化。使用 GnRH 治疗增加了 PGF 时具有 CL 的奶牛比例；然而，2CIDR 方案在所有情况下都增加了循环 P4。
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