Kesler D J
Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA.
Theriogenology. 1997 Jul 1;48(1):89-98. doi: 10.1016/S0093-691X(97)00193-3.
Fifty-five heifers were synchronized with norgestomet and estradiol valerate and artificially inseminated approximately 48 h after the removal of norgestomet implants. Ten days after Al, 15 of the heifers were ovariectomized and then two 15 mg norgestomet/silicone implants were implanted subcutaneously on the convex surface of the ear. The norgestomet/silicone implants were changed every 55 +/-4 d (mean range) thereafter, and the last set of implants was removed 273 d after Al. At 44 d after Al, 65% (26/40) of the control heifers and 53% (8/1 5) of the ovariectomized heifers with norgestomet implants were pregnant (P > 0.10). Two pregnancies were lost in ovariectomized heifers treated with norgestomet (44 to 96 d after Al) and a third pregnancy failed in a heifer that lost 1 of 2 implants 65 to 96 d after Al. Ninety-six days after Al implants were removed from 2 pregnant ovariectomized heifers with norgestomet implants. These 2 heifers were open at 116 d after Al. All 3 ovariectomized heifers with norgestomet implants pregnant at 273 d after Al calved an average of 41 h after the removal of the last set of norgestomet/silicone implants. Dystocia (P < 0.05), retention of fetal membranes (P < 0.01), and calf mortality (P < 0.01) were higher for the ovariectomized heifers with norgestomet implants than for the control heifers.
55头小母牛用诺孕美特和戊酸雌二醇进行同期发情处理，在取出诺孕美特埋植剂后约48小时进行人工授精。人工授精后10天，15头小母牛进行卵巢切除，然后在耳朵凸面皮下植入两个15毫克诺孕美特/硅胶埋植剂。此后，诺孕美特/硅胶埋植剂每55±4天（平均范围）更换一次，最后一组埋植剂在人工授精后273天取出。人工授精后44天，对照小母牛中有65%（26/40）怀孕，植入诺孕美特的卵巢切除小母牛中有53%（8/15）怀孕（P>0.10）。植入诺孕美特的卵巢切除小母牛中有2例怀孕丢失（人工授精后44至96天），第三例怀孕失败发生在一头小母牛身上，该小母牛在人工授精后65至96天丢失了2个埋植剂中的1个。从2头植入诺孕美特的怀孕卵巢切除小母牛中取出埋植剂后96天。这2头小母牛在人工授精后116天未怀孕。所有3头植入诺孕美特的卵巢切除小母牛在人工授精后273天怀孕，在取出最后一组诺孕美特/硅胶埋植剂后平均41小时产犊。植入诺孕美特的卵巢切除小母牛的难产率（P<0.05）、胎膜滞留率（P<0.01）和犊牛死亡率（P<0.01）高于对照小母牛。
