Penny C D, Lowman B G, Scott N A, Scott P R
Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Easter Bush, Roslin, Midlothian.
Vet Rec. 1997 May 10;140(19):496-8. doi: 10.1136/vr.140.19.496.
The feasibility of breeding spring-calving, single-suckled beef cows without the use of natural service was investigated over two breeding seasons by using repeated oestrus synchrony and fixed-time artificial insemination (AI). Initially, cows were oestrus-synchronised with subcutaneous norgestomet implants inserted for 10 days, with an injection of prostaglandin before the implants were removed. The cows were inseminated once 56 hours after the implants were removed, and 12 days later they were re-treated with norgestomet implants to allow a second synchronised service. Twenty-one days after the first synchronised AI, milk samples were taken for progesterone assay and the norgestomet implants were removed. The cows received a second service 56 hours later if the 21-day milk progesterone assay suggested that they were not pregnant. All the cows receiving a second service were retreated with norgestomet implants to allow a third synchronised service as necessary. Pregnancy was later confirmed by rectal palpation. In the first year, 48 cows entered the programme and the pregnancy rates to the first, second and third synchronised services were 56, 69 and 40 per cent, respectively, with 17 per cent of cows barren at the end of the breeding period. In the second year, 69 cows entered the programme and the pregnancy rates were 58, 48 and 33 per cent to the successive services with 20 per cent of cows barren at the end of the breeding period. The accuracy of milk progesterone assay for pregnancy diagnosis was 84 per cent and 87 per cent in the first and second years, respectively.
在两个繁殖季节里，通过反复发情同步化和定时人工授精（AI），研究了不采用自然交配方式饲养春季产犊、单胎哺乳肉牛的可行性。最初，给母牛皮下植入诺孕美特10天进行发情同步化处理，在取出植入物前注射前列腺素。取出植入物56小时后对母牛进行一次人工授精，12天后再次用诺孕美特植入物处理，以便进行第二次同步配种。第一次同步人工授精21天后，采集牛奶样本进行孕酮检测，并取出诺孕美特植入物。如果21天的牛奶孕酮检测表明母牛未怀孕，56小时后对其进行第二次配种。所有接受第二次配种的母牛都再次用诺孕美特植入物处理，以便必要时进行第三次同步配种。随后通过直肠触诊确认妊娠情况。第一年，48头母牛参与该项目，第一次、第二次和第三次同步配种的妊娠率分别为56%、69%和40%，繁殖期结束时17%的母牛未受孕。第二年，69头母牛参与该项目，连续几次配种的妊娠率分别为58%、48%和33%，繁殖期结束时20%的母牛未受孕。第一年和第二年，牛奶孕酮检测用于妊娠诊断的准确率分别为84%和87%。
