A longitudinal study of tick infestations and management practices in young stock smallholder dairy cattle in the Tanga region, Tanzania

Abstract

A longitudinal study involving cohorts of young stock animals (<3 years old) kept on smallholder dairy farms in the Tanga region, Tanzania, was conducted to identify and quantify tick infestations and describe on-farm tick management practices. A total of 549 young stock were followed for 23 months, and 3127 grazing and acaricide treatment observations were obtained. Tick counts were low in the present study, and while more than 30% of animals had a tick on one occasion, most animals had no ticks at most examinations. The most commonly encountered spp. were R. appendiculatus, Boophilus spp., A. variegatum and R. evertsi. Most animals were zero-grazed, a management system that significantly limits animal exposure to ticks; however, grazed calves were more than three times more likely to carry R. appendiclatus and Boophilus spp. ticks than zero-grazed calves were (OR [odds ratio] = 4.4, P < 0.001; 3.6, P < 0.001). There were no significant differences among sampling rounds in the numbers of animals carrying R. appendiculatus ticks (likelihood ratio test P = 0.520). Hand spraying was the common method used, acaricides that require on farm dilution were most commonly used, and most farmers used this method at concentrations considerably less than those recommended by the manufacturer, most likely due to poor understanding, high cost (tempting them to over dilute) and weak extension/veterinary services. Variation in acaricide treatment frequency was not associated with variations in tick attachment, suggesting that most farms were under a strong acaricide regime or at irregular intervals or with tick-building resistance. Our findings suggest that geographic variations in vector densities might partly influence the extent of infection caused by tick-borne pathogens. The applicability of this study to large and extensive cattle production systems is recommended to widen the scope of tick management practices while generating additional data that will inform national tick and tick-borne disease control policy reform in Tanzania.