Masunda B, Mutisi C, Hamudikuwanda H, Agumbah J G O
Department of Animal Science, University of Zimbabwe, PO Box MP 167, Mt Pleasant, Harare, Zimbabwe.
Trop Anim Health Prod. 2002 Jul;34(4):309-18. doi: 10.1023/a:1015682718761.
The objectives of this study were to investigate the relationship between the concentrations of progesterone (P4) in the peripheral circulation and progestins in the faeces of cows in a smallholder farming area and to monitor the ovarian activity of such cows. The study was carried out in Sanyati smallholder farming area, located 250 km southwest of Harare. Blood and faecal samples for P4 and progestin determination, respectively, were obtained once a week from 35 Mashona type cows that belonged to farmers from three different villages. The cows were weighed once every month and all births were recorded. The concentrations of progestins in faeces and P4 in plasma were positively correlated (r = 0.72, p < 0.01). Most of the non-pregnant cows (65%) cycled during the rainy season. Most of those that were acyclic at this time were undergoing post-partum anoestrus. During the dry season, most cows (58%) became acyclic as forage became scarce and of poor quality. Thirty-two calves were born during the study period, mostly during the first or last two months of the year, when there was enough forage. The mean calving to first oestrus in 14 cows that recalved was 71 +/- 49 days. Eight of these 14 cows conceived again, the calving to conception interval being 173 +/- 94 days. The cows' liveweights were highest in April, at the end of the rainy season. By the end of the dry season, the cows had lost, on average, 15% of their peak weight.
本研究的目的是调查小农户养殖区奶牛外周循环中孕酮（P4）浓度与粪便中孕激素之间的关系，并监测此类奶牛的卵巢活动。该研究在位于哈拉雷西南250公里处的萨尼亚蒂小农户养殖区进行。每周从来自三个不同村庄的农民所拥有的35头马绍纳类型奶牛中分别采集血液和粪便样本，用于测定P4和孕激素。每月对奶牛称重一次，并记录所有出生情况。粪便中孕激素浓度与血浆中P4浓度呈正相关（r = 0.72，p < 0.01）。大多数未怀孕的奶牛（65%）在雨季发情。此时大多数不发情的奶牛处于产后乏情期。在旱季，随着草料变得稀少且质量不佳，大多数奶牛（58%）停止发情。在研究期间有32头小牛出生，大多在一年中的第一个月或最后两个月，那时有足够的草料。14头产犊奶牛从产犊到首次发情的平均间隔为71 +/- 49天。这14头奶牛中有8头再次受孕，从产犊到受孕的间隔为173 +/- 94天。奶牛的体重在雨季结束时的4月份最高。到旱季结束时，奶牛的体重平均比峰值体重下降了15%。
