The castor bean tick (Ixodes ricinus) is a widespread European ectoparasite and vector of multiple diseases that can impair cattle health and productivity. This study evaluated whether a single application of a gel microencapsulated acaricide (α-cypermethrin and permethrin) reduces I. ricinus infestation in dairy cows and affects milk yield. Twenty cows were allocated to treated and control groups; treated animals received one spray at the start of the grazing season, and tick counts were recorded daily for 196 days with monthly milk-yield measurements. Two activity peaks were observed (June and September–October) with reduced abundance in July–August; all control cows were parasitised, with daily counts of 1–18 ticks (median = 2). During the first month after treatment, the acaricide reduced tick numbers by around 80% versus controls (p < 0.001); efficacy declined over the ensuing months, and differences were negligible after about five months. No adverse effect on milk yield was detected (p = 0.38), and seasonal variation (p < 0.0001) and lactation stage (p < 0.001) were the primary determinants of production. Primiparous and young cows, as well as cows in mid-to-late lactation, tended to show higher levels of tick infestation. A single application of the gel microencapsulated product provided a significant reduction in tick burden during the first month after treatment in grazing dairy cows, without a negative impact on milk production, supporting its use in endemic areas.
Kucharska et al. (Wed,) studied this question.