Non-invasive indicators associated with the milk yield response after anthelmintic treatment at calving in dairy cows

Abstract

Background: Gastrointestinal nematodes are an important cause of reduced performance in cattle. Previous studies in Europe showed that after anthelmintic treatment an average gain in milk production of around 1 kg per day/ cow can be expected. However, (1) these studies have mainly evaluated group-based anthelmintic treatments during the grazing season or at housing and (2) little is known about parameters affecting variations in the treatment response amongst cows. A better knowledge of such parameters could help to select animals that benefit most from treatment and thus lead to a more rational use of anthelmintics. Therefore, a randomized, non-blinded, controlled clinical trial was performed on 11 commercial dairy farms (477 animals) in Belgium, aiming (1) to study the effect of eprinomectin treatment at calving on milk production and (2) to investigate whether the milk yield response was related to non-invasive animal parameters such that these could be used to inform targeted selective treatment decisions. Results: Analyses show that eprinomectin treatment around calving resulted in an average (± standard error) increase of 0.97 (±0.41) kg in daily milk yield that was followed up over 274 days on average. Milk yield responses were higher in multiparous compared to primiparous cows and in cows with a high (4 th quartile) anti-O. ostertagi antibody level in a milk sample from the previous lactation. Nonetheless, high responses were also seen in animals with a low (1 st quartile) anti-O. ostertagi antibody level. In addition, positive treatment responses were associated with higher faecal egg counts and a moderate body condition score at calving (2 nd quartile).

Treatment of livestock with systemic insecticides for control of Anopheles arabiensis in western Kenya

“…Eprinomectin has established utility in the agricultural industry as an effective means to control endoparasite loads in cattle [ 31 ], with the additional health benefits of increasing cattle weight gain and milk production [ 31 , 47 ]. However, eprinomectin has not been widely used for public health purposes.…”

Decision making on helminths in cattle: diagnostics, economics and human behaviour

“…Such information is increasingly available, especially to evaluate the production effects of strategic anthelmintic usage e.g. [ 23 , 24 ], and this information was used to develop the second tool “treatment strategies against gastrointestinal worms” on ParaCalc.com. It estimates the likely economic benefit and uncertainty of a number of anthelmintic treatment strategies of adult cows and produces a report to discuss with the farmer.…”

Unexpected Decrease in Milk Production after Fenbendazole Treatment of Dairy Cows during Early Grazing Season

“…In adult grazing dairy cows, looking at the large variability of the effect of anthelmintic treatment on MP among studies, between herds and between cows [ 10 , 11 , 20 – 26 ], there appears both a need and an opportunity to use anthelmintics in a more targeted and selective way. In targeted treatment (TT) and targeted-selective treatment (TST) strategies, treatments are restricted to herds, and cows within herds, that will most benefit from treatment (TST), drug being administered at the most appropriate time(s) (TT), bearing in mind the need to maintain susceptible parasites in refugia (parasites unexposed to drug, i.e.…”

“…But this whole herd repeated-treatment strategy is of course questionable if we keep in mind the need to preserve a large population of parasites in refugia . In other studies, a single treatment was applied, not in a given season and to the entire herd at the same time, but all over the year, at a given physiological stage, namely at calving or drying off [ 24 , 26 , 41 – 47 ]. Unfortunately, the majority of these studies did not provide a comparison of the effects on MP of treatments applied during housing period (autumn-winter) versus grazing season (spring, summer, and early autumn).…”

“…Indeed, either the effect of season on the MP response after anthelmintic treatment was not investigated [ 24 , 43 , 45 – 47 ], or failed to be detected because of a possible lack of statistical power, as pointed out by the authors [ 44 ], or because seasons were not sufficiently distinguishable to be compared [ 41 , 42 ]. Only one recent study reported that the treatment effects were similar during housing versus pasture period [ 26 ].…”