Rawlings N C, Howell W E
Dept. of Vet. Physiol. Sci., University of Saskatchewan, Saskatoon, Canada.
J Anim Sci. 1988 Apr;66(4):851-4. doi: 10.2527/jas1988.664851x.
The induction and management of lambing was studied in a commercial flock of ewes. These ewes were bred at synchronized estrus and managed to lamb three times in 2 yr, with lambings occurring in the sequence of February, September and June. Ewes treated with 2 mg of estradiol benzoate in oil (i.m.) at approximately 17 d prior to term did not lamb in response to treatment. When 2 mg estradiol benzoate was given at 0800 on d 142 of gestation, lambing occurred an average of 37 +/- 5 h later in ewes treated in June or September and at 70 +/- 10 h later in ewes treated in February. The comparable figures for oil-treated ewes (control) were 70 +/- 5 h and 116 +/- 9 h, respectively. Altering the time of day of injection or using two injections 24 h apart did not alter the time for injection to lambing. Increasing the dose of estradiol benzoate to 15 mg decreased the time from injection to lambing (43 +/- 7 h, ewes treated in February) but also increased the incidence of dystocia (50% incidence). The incidence of dystocia averaged 8% for all other treatments and controls. Death loss of lambs to 1 wk of age was 12% and was not affected by treatment. The length of the lambing period was reduced from 9.0 +/- 3.3 d in control ewes to 3.6 +/- 1.1 d in induced ewes. A single injection of 2 mg estradiol benzoate given at 0800 on d 142 of gestation or a double treatment, with injections at 2000 on d 142 and 143, resulted in 53% of ewes lambing between 0800 and 1600 on each day of the lambing period, compared with 33% in control ewes.
在一个商业化母羊群中研究了产羔的诱导和管理。这些母羊在同步发情时进行配种，并设法在两年内产羔三次，产羔时间依次为2月、9月和6月。在预产期前约17天肌肉注射2毫克油剂苯甲酸雌二醇的母羊对治疗无反应而未产羔。在妊娠第142天的08:00给予2毫克苯甲酸雌二醇时，6月或9月接受治疗的母羊平均在37±5小时后产羔，2月接受治疗的母羊平均在70±10小时后产羔。油剂处理的母羊（对照组）的相应数字分别为70±5小时和116±9小时。改变注射时间或每隔24小时注射两次并未改变注射到产羔的时间。将苯甲酸雌二醇的剂量增加到15毫克可缩短注射到产羔的时间（2月接受治疗的母羊为43±7小时），但也增加了难产的发生率（发生率为50%）。所有其他处理和对照组的难产发生率平均为8%。羔羊至1周龄的死亡率为12%，不受处理影响。产羔期的长度从对照母羊的9.0±3.3天缩短至诱导母羊的3.6±1.1天。在妊娠第142天的08:00单次注射2毫克苯甲酸雌二醇或在第142天和143天的20:00进行两次注射，导致53%的母羊在产羔期的每一天的08:00至16:00之间产羔，而对照母羊为33%。
