Loughnan T, Mansell P, Playford M, Beggs D
Colac Veterinary Clinic, Colac, VIC 3250, Australia.
Melbourne Veterinary School, Faculty of Veterinary Science, University of Melbourne, Werribee, VIC 3030, Australia.
JDS Commun. 2024 Jun 28;5(6):664-668. doi: 10.3168/jdsc.2024-0555. eCollection 2024 Nov.
Anthelmintic use in lactating dairy cattle has been shown to result in a milk production response in some previous studies. If individual animals within a herd could be identified that would most benefit from anthelmintic treatment, this may reduce anthelmintic resistance. Australian dairy systems are predominantly pasture based, allowing sustained exposure and immune stimulation of cattle to gastrointestinal nematodes. We assessed the relationship between milk production and early-lactation fecal egg counts (FEC) to determine whether cows with higher FEC produced less milk. Ten pasture-based dairy farms in south-west Victoria, Australia, entered an observational study. Individual FEC at a minimum detectable count of 2.5 eggs per gram of feces (epg) were recorded for recently calved primiparous and multiparous cohorts on each farm. All animals were calved ≤30 d at sampling. Body condition scores were assessed at sampling and milk production data were collected from daily milk meters and herd tests to give first 100-d milk production. When separated by primiparous or multiparous status, no difference in the milk production between cows with FEC = 0 and FEC ≥2.5 epg was identified. Between-farm variation was large for FEC and milk production. Fecal egg count at a minimum detectable count of 2.5 epg detected parasitism in primiparous cows postcalving, but the presence and magnitude of parasitism measurable by FEC was not related to milk production in pasture-based Australian dairy systems. In multiparous cows, the rate detection of worm eggs at this analytical sensitivity was lower and the significance of a positive FEC at this analytical sensitivity requires further assessment to ascertain the effect on milk production. Based on our study, it seems unlikely that individual FEC results would be useful as a basis to select individual cows in south-west Victorian dairy herds for anthelmintic treatment.
在一些先前的研究中，已表明在泌乳奶牛中使用驱虫药会带来产奶量的变化。如果能够识别出畜群中最能从驱虫治疗中受益的个体动物，这可能会降低驱虫药耐药性。澳大利亚的奶牛养殖系统主要以牧场为基础，使奶牛持续接触胃肠道线虫并受到免疫刺激。我们评估了产奶量与泌乳早期粪便虫卵计数（FEC）之间的关系，以确定FEC较高的奶牛产奶量是否较低。澳大利亚维多利亚州西南部的10个以牧场为基础的奶牛场参与了一项观察性研究。记录了每个农场最近产犊的初产和经产奶牛群个体的FEC，最低可检测计数为每克粪便2.5个虫卵（epg）。所有动物在采样时产犊均≤30天。在采样时评估体况评分，并从每日奶量计和牛群检测中收集产奶量数据，以得出前100天的产奶量。按初产或经产状态分开时，未发现FEC = 0和FEC≥2.5 epg的奶牛在产奶量上有差异。FEC和产奶量的农场间差异很大。最低可检测计数为2.5 epg的粪便虫卵计数可检测到初产奶牛产后的寄生虫感染，但在澳大利亚以牧场为基础的奶牛养殖系统中，FEC可测量的寄生虫感染的存在和程度与产奶量无关。在经产奶牛中，在此分析灵敏度下检测到虫卵的比率较低，在此分析灵敏度下FEC呈阳性的意义需要进一步评估，以确定对产奶量的影响。根据我们的研究，在维多利亚州西南部的奶牛群中，个体FEC结果似乎不太可能作为选择个体奶牛进行驱虫治疗的依据。
