Jubb T F, Fordyce G, Bolam M J, Hadden D J, Cooper N J, Whyte T R, Fitzpatrick L A, Hill F, D'Occhio M J
Agriculture Western Australia, PO Box 19, Kununurra, WA 6743.
Aust Vet J. 2003 Jan-Feb;81(1-2):66-70. doi: 10.1111/j.1751-0813.2003.tb11436.x.
To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia.
Three field trials were conducted simultaneously at different sites in northern Australia in 1996-97. Brahman and Brahman-Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared.
Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% successful in preventing pregnancy; the WDOT was 92 to 97% effective, depending on operator experience. The number of deaths was the same or higher in Willis spayed animals than other groups. Weight changes were similar in all groups at the three sites over the trial period. The time taken to spay using the WDOT was similar to or less than that required for the traditional methods. Uterine abnormalities were not observed in animals spayed with the WDOT, there were however 30 (12.4%) animals where excision of the ovary was incomplete; the still-attached ovarian remnant presumably accounting for the three pregnant animals in this group.
The WDOT suffers from requiring a high degree of skill in transrectal ovarian manipulation. There were more deaths and more pregnancies than with traditional spay methods. More experienced operators can be expected to achieve lower mortalities, better contraception and higher processing rates. Pregnancy will occur as a consequence of ovarian remnants unless care is taken to ensure removal of the entire ovary.
在澳大利亚北部的广大肉牛群中，比较威利斯下垂卵巢技术与传统去势方法。
1996 - 1997年在澳大利亚北部不同地点同时进行了三项田间试验。婆罗门牛和婆罗门 - 短角牛杂交的小母牛（n = 219头，2岁，体重250至378千克）和母牛（n = 211头，3至16岁，体重256至540千克）通过分层随机化分配到三种处理方式：采用威利斯下垂卵巢技术（WDOT）去势；采用传统的腰旁和阴道方法去势；以及不去势。经过这些程序后，这些未怀孕、未泌乳的牛随后在广阔的牧场条件下与公牛接触（每100头母牛4头公牛），为期12个月，在此期间监测并比较体重、身体状况、怀孕情况和卵巢功能。
根据地点不同，未去势小母牛的怀孕率在60%至90%之间，未去势母牛的怀孕率在80%至100%之间。传统去势方法在预防怀孕方面成功率为100%；WDOT的有效率为92%至97%，具体取决于操作人员的经验。威利斯去势的动物死亡数量与其他组相同或更高。在试验期间，三个地点所有组的体重变化相似。使用WDOT去势所需时间与传统方法相似或更短。采用WDOT去势的动物未观察到子宫异常，然而有30头（12.4%）动物的卵巢切除不完全；仍附着的卵巢残余可能是该组三头怀孕动物的原因。
WDOT存在经直肠操作卵巢需要高度技巧的问题。与传统去势方法相比，死亡和怀孕情况更多。预计经验更丰富的操作人员可实现更低的死亡率、更好的避孕效果和更高的处理率。除非小心确保切除整个卵巢，否则卵巢残余会导致怀孕。
