Bisset S A, Marshall E D, Morrison L
Wallaceville Animal Research Centre, Ministry of Agriculture and Fisheries, Upper Hutt New Zealand.
Vet Parasitol. 1987 Dec;26(1-2):119-29. doi: 10.1016/0304-4017(87)90082-3.
The results of a series of trials conducted on 47 seasonal supply dairy farms in the southern North Island of New Zealand, which indicated a statistically significant overall production response of 2.24 kg milkfat/cow/lactation following a 2-treatment dry-cow anthelmintic drenching programme (Bisset et al., 1987), were subjected to further analyses in an attempt to identify any management factors or herd characteristics which may have influenced the levels of production response to treatment in individual herds. The management factors examined included calf drenching practices, types of grazing system, mean pre-calving condition of the herds, and 'nutritional status' of the herds over the milking season. The influence of herd quality, herd size and geographical location were also examined. Considered separately, only calf drenching practice had a significant influence on the level of herd response to treatment. Increases in milkfat production/cow due to the treatment programme were significantly greater (P less than 0.05, t-test) on farms where calves had received a minimal number of drench treatments (less than or equal to 2) between weaning and the end of March (mid-autumn) (+5.32 kg/cow/lactation, P less than 0.01) (= 108.2 l milk), than on farms where calves had received regular 3-4 weekly treatments over the same period (+0.42 kg/cow/lactation, N.S.) While none of the other factors, considered in isolation, appeared to significantly influence the production response of herds, observations on possible interactive effects suggested that the grazing system employed was probably of importance in so far as it determined the level of exposure of cows to calf-contaminated pasture. Thus, the greatest mean response to the treatment programme occurred in herds where cows were overwintered on areas grazed during the milking season by calves which had received less than or equal to 2 drench treatments from weaning until the end of March (+5.95 kg milkfat/cow/lactation, P less than 0.01).
在新西兰北岛南部的47个季节性供应奶牛场进行了一系列试验，结果表明，在实施两阶段干奶牛驱虫灌药方案后，每头奶牛每个泌乳期的乳脂产量总体增产2.24千克，具有统计学显著意义（比塞特等人，1987年）。为了确定可能影响各牛群对治疗的生产反应水平的任何管理因素或牛群特征，对这些结果进行了进一步分析。所考察的管理因素包括犊牛灌药做法、放牧系统类型、牛群产犊前的平均状况以及挤奶季节牛群的“营养状况”。还考察了牛群质量、牛群规模和地理位置的影响。单独来看，只有犊牛灌药做法对牛群对治疗的反应水平有显著影响。在犊牛在断奶至3月底（中秋）期间接受最少灌药处理（小于或等于2次）的农场，治疗方案使每头奶牛的乳脂产量增加显著更大（P小于0.05，t检验）（每头奶牛每个泌乳期增加5.32千克，P小于0.01）（相当于108.2升牛奶），而在同一时期犊牛接受定期每周3 - 4次灌药处理的农场，每头奶牛每个泌乳期增加0.42千克（无显著差异）。虽然单独考虑的其他因素似乎都没有对牛群的生产反应产生显著影响，但对可能的交互作用的观察表明，所采用的放牧系统可能很重要，因为它决定了奶牛接触受犊牛污染牧场的程度。因此，对治疗方案的平均反应最大的是那些奶牛在挤奶季节放牧区域越冬的牛群，这些区域在断奶至3月底期间接受小于或等于2次灌药处理的犊牛曾在此放牧（每头奶牛每个泌乳期乳脂产量增加5.95千克，P小于0.01）。
