Norval R A, Sutherst R W, Jorgensen O G, Kerr J D
Veterinary Research Laboratory, Causeway, Harare, Zimbabwe.
Med Vet Entomol. 1997 Apr;11(2):143-7. doi: 10.1111/j.1365-2915.1997.tb00304.x.
The effects of adults on the bont tick, Amblyomma hebraeum on the milk production of Sanga and Sanga x zebu (Brahman) cattle were measured over a period of 11 weeks in the low veld of Zimbabwe in the summer of 1986. Four groups of lactating cows, consisting of two breeds, each divided into a high and low tick treatment, were exposed to very low or high challenges of ticks and their milk production measured by weighing their calves before and after suckling. The liveweight gains (LWG) of the calves were also measured. Tick burdens on the infested groups averaged around fourteen engorging females of A.hebraeum per day, which amounted to infestations of about 150 adult ticks. This is greater than most observed field infestations. This caused no significant reduction in milk yield or calf growth over the whole period, provided the teats of the dams had not been damaged by ticks. Mismothering occurred when teats were damaged. No breed differences were observed so all data was pooled for further analysis. Average calf LWGs of the high tick groups were reduced by 2.2 kg (P < 0.01) during one 4-week period but overall the 3.9 kg difference in LWG of the tick treatment groups was not quite significant (P < 0.10). Although there was a poor relationship between tick numbers and reduced milk yield or calf LWG, the effects were always in the direction expected. The effects averaged 6 +/- 10 g reduction of milk and 2.6 +/- 1.8 g loss of LWG of calves for every female tick that engorged. it was concluded that milk production is not an important consideration when estimating the losses in production caused by A.hebraeum on Brahman x Sanga or Sanga breeds of cattle. Losses due to teat or udder damage could be much more important and need to be quantified.
1986年夏天，在津巴布韦低地草原进行了为期11周的研究，测定成年非洲牛蜱（Amblyomma hebraeum）对桑加牛以及桑加牛与瘤牛（婆罗门牛）杂交牛产奶量的影响。四组泌乳母牛，分属两个品种，每组再分为高蜱虫处理组和低蜱虫处理组，分别接受极低或极高的蜱虫挑战，通过称量犊牛哺乳前后的体重来测定母牛的产奶量。同时也测量了犊牛的体重增加量（LWG）。受蜱虫侵袭组的蜱虫负担平均为每天约十四只饱血的非洲牛蜱雌虫，相当于约150只成年蜱虫的侵扰。这比大多数实际观察到的田间侵扰情况更为严重。在整个期间，只要母牛的乳头未被蜱虫损伤，这并未导致产奶量或犊牛生长显著下降。当乳头受损时会发生错母行为。未观察到品种差异，因此所有数据合并进行进一步分析。在一个为期4周的时间段内，高蜱虫组的犊牛平均LWG减少了2.2千克（P < 0.01），但总体而言，蜱虫处理组LWG的3.9千克差异并不十分显著（P < 0.10）。尽管蜱虫数量与产奶量减少或犊牛LWG之间的关系不紧密，但影响总是符合预期方向。每只饱血雌蜱虫导致的产奶量平均减少6 +/- 10克，犊牛LWG损失2.6 +/- 1.8克。得出的结论是，在估计非洲牛蜱对婆罗门牛与桑加牛杂交种或桑加牛品种造成的生产损失时，产奶量并非重要考量因素。因乳头或乳房损伤造成的损失可能更为重要，需要进行量化。
