Hill G M, Lucas D M, Richardson K L, Baker J F, Kiser T E
Department of Animal Science University of Georgia College of Agriculture Coastal Plain Experiment Station Tifton, GA 31793-0748 USA.
Theriogenology. 1992 Mar;37(3):619-29. doi: 10.1016/0093-691x(92)90142-e.
A 122-day trial was conducted with grazing beef heifers (N=120; 14 to 17 months of age) to determine the effects of a silastic Norgestomet prototype implant on heifer weight gain and on the suppression of ovarian luteal activity. The retention rate of the Norgestomet implants and of silastic placebo implants, which were either left untreated, or were topically treated with oxytetracycline, was determined. Medication of the placebo implants with oxytetracycline increased (P < 0.01) implant retention rate at both Day 56 and Day 122. Heifers with Norgestomet implants had higher body weight gains during the last 66 days (P < 0.05), and during the entire 122-day trial (P < 0.07) than heifers with placebo implants. Serum progesterone concentrations on Day 111 or Day 112 indicated a decrease (P < 0.01) in percentage of heifers with ovarian luteal activity on the Norgestomet treatment compared with heifers receiving placebos (23.8% vs 87.7%, respectively). The Norgestomet implant has the potential for suppressing ovarian luteal activity while improving weight gain in beef heifers.
对120头14至17月龄的放牧小母牛进行了为期122天的试验，以确定硅橡胶炔诺孕酮原型植入物对小母牛体重增加和抑制卵巢黄体活动的影响。测定了炔诺孕酮植入物和硅橡胶安慰剂植入物（未处理或局部用土霉素处理）的留存率。在第56天和第122天，用土霉素处理安慰剂植入物均提高了（P < 0.01）植入物留存率。与植入安慰剂的小母牛相比，植入炔诺孕酮的小母牛在最后66天（P < 0.05）以及整个122天试验期间（P < 0.07）体重增加更多。第111天或第112天的血清孕酮浓度表明，与接受安慰剂的小母牛相比，接受炔诺孕酮处理的小母牛卵巢黄体活动的百分比有所下降（P < 0.01）（分别为23.8%和87.7%）。炔诺孕酮植入物有可能在抑制牛肉小母牛卵巢黄体活动的同时提高体重增加。
