Fordyce G, Jubb T F, Fitzpatrick L A, Whyte T R, Cooper N J, Bolam M J, Haddon D J, Hill F, D'Occhio M J
Department of Primary Industries, Queensland Beef Industry Institute, P.O. Box 976, Qld. 4820, Charters Towers, Australia.
Anim Reprod Sci. 2001 Mar 30;65(3-4):193-204. doi: 10.1016/s0378-4320(01)00081-1.
The contraceptive efficacy of an intra-uterine device was evaluated using 218 heifers and 212 cows on three north Australian cattle stations. The heifers were aged approximately 2 years and weighed 250-378 kg; the cows were aged 3-16 years and weighed 256-540 kg. All cattle were non-pregnant, non-lactating Brahmans. At the end of the monsoon (wet) season (April-June 1997), the cattle were allocated by stratified randomisation to the three treatments which were untreated controls (n=59), surgical ovariectomy (n=105), or implantation with a bovine intra-uterine device (BIUD; n=266). All cattle grazed and were managed as one group within each station. They were exposed to bulls (4 per 100 females) from soon after treatment until slaughter approximately 12 months later. The BIUD could not be implanted in 25% of heifers and 8% of cows due to narrow or twisted cervices. Correct placement of the BIUDs appeared to be achieved in 57% of heifers and 72% of cows. At slaughter, the devices were incorrectly positioned in 73% of heifers and 49% of cows into which BIUDs had been inserted and that remained non-pregnant. Uterine perforations by the BIUD were observed in 35 and 45% of these heifers and cows, respectively; most perforations appeared to occur during implantation. Low-grade endometritis was observed at slaughter in most BIUD-implanted animals; 2% had pyometra.BIUD animals did not have significantly different growth to that of control or ovariectomised animals, other than when ovariectomy suppressed growth following surgery. Most animals implanted with BIUDs appeared to have normal ovarian function and animals were observed mating. All ovariectomised animals remained non-pregnant. Over 80% of controls were pregnant within 8 months of exposure to bulls, except heifers at one station where pregnancy rate was restricted to 25% as a result of severe nutritional conditions. Pregnancy was diagnosed in 21% of heifers and 33% of cows with implanted BIUDs. The device remained correctly positioned and with no pregnancy diagnosed in the year following implantation in only 2% of heifers and 14% of cows originally allocated. Because of the difficulties of implanting BIUDs, the high frequency of associated uterine injury, the high pregnancy rate in implanted animals, and that growth was unaffected by the presence of a BIUD, it was concluded that the device had poor contraception efficacy and no growth-promotant effect in Brahman cattle.
在澳大利亚北部的三个养牛场，使用218头小母牛和212头母牛对一种宫内节育器的避孕效果进行了评估。小母牛年龄约2岁，体重250 - 378千克；母牛年龄3 - 16岁，体重256 - 540千克。所有牛均为非妊娠、非泌乳的婆罗门牛。在季风（雨季）季节结束时（1997年4月至6月），通过分层随机化将牛分配到三种处理组，即未处理的对照组（n = 59）、手术去势组（n = 105）或植入牛用宫内节育器（BIUD；n = 266）。每个养殖场内的所有牛作为一组进行放牧和管理。从处理后不久到大约12个月后屠宰，它们都与公牛接触（每100头母牛配4头公牛）。由于子宫颈狭窄或扭曲，25%的小母牛和8%的母牛无法植入BIUD。在57%的小母牛和72%的母牛中似乎成功植入了BIUD。屠宰时，在已植入BIUD且仍未怀孕的小母牛和母牛中，分别有73%和49%的节育器位置不正确；在这些小母牛和母牛中，分别有35%和45%观察到BIUD导致子宫穿孔，大多数穿孔似乎发生在植入过程中。在大多数植入BIUD的动物屠宰时观察到轻度子宫内膜炎；2%的动物患有子宫积脓。除了去势手术抑制生长的情况外，植入BIUD的动物与对照或去势动物的生长没有显著差异。大多数植入BIUD的动物似乎具有正常的卵巢功能，并且观察到动物进行交配。所有去势动物均未怀孕。超过80%的对照组在接触公牛后8个月内怀孕，但有一个养殖场的小母牛由于严重的营养状况，怀孕率仅为25%。植入BIUD的小母牛中有21%、母牛中有33%怀孕。在最初分配的小母牛中，只有2%、母牛中只有14%在植入后的一年中节育器位置正确且未诊断出怀孕。由于植入BIUD存在困难、相关子宫损伤的高发生率、植入动物的高怀孕率以及BIUD的存在对生长没有影响，得出的结论是，该节育器在婆罗门牛中的避孕效果不佳，且没有促生长作用。
