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

摘要: Gastrointestinal nematodes (GIN) infection can impair milk production (MP) in dairy cows. To investigate whether MP would be optimized by spring targeted-selective anthelmintic treatment grazing cows, we assessed (1) the effect on of an applied 1.5 to 2 months after turn-out, and (2) herd individual indicators associated with post-treatment response. A randomized controlled clinical trial was conducted 13 farms (578 cows) western France 2012. In each herd, lactating cows group received fenbendazole orally, control remained untreated. Daily cow recorded from weeks before until 15 treatment. Individual serum pepsinogen anti-Ostertagia antibody levels (expressed as ODR), faecal egg count bulk tank (BTM) Ostertagia ODR were measured at time. Anthelmintic during previous housing period for cow. information regarding heifers’ history collected assess Time Effective Contact (TEC, months) GIN infective larvae first calving. The weekly averages its relationships studied using linear mixed models two nested random effects (cow within herd). Unexpectedly, had a significant detrimental (-0.92 kg/cow/day average). This negative response particularly marked high producing not treated or levels, herds TEC BTM ODR. decrease may immuno-inflammatory mechanisms. Until further studies this unexpected result generalized, non-persistent immunized adult against should recommended early season.