Tick loads in Bos taurus cattle grazing in two contrasting production systems

Objectives. To relate the effect of biotic and abiotic factors on Rhipicephalus (Boophilus) microplus tick loads on cows grazing either in intensive silvopastoral systems (ISS) (Lucerna) or in grass pastures associated with sugarcane plantations (La Isabela). Materials and methods. Tick counts were performed on 27 Lucerne breed animals that were in different physiological states, six of which were grazing on forage grass paddocks associated with commercial sugarcane plantations and the remaining animals grazed in an ISS based on Leucaena leucocephala and Cynodon plectostachyus. The tick counts were made every 15 days. The data of temperature, humidity, and radiation were taken from a weather station that was inside the ISS. Results. There was a weak relationship between saturation deficit and tick load (R2=0.34) and another between UV radiation and tick load (R2=0.205) for animals grazing in ISS. There were differences in tick counts when comparing animals of similar productivity from both systems evaluated: in La Isabela (sugarcane grass paddocks) average counts were 311 ticks perceptible to the touch (TPT) and in Lucerna (ISS farm) average counts were 206 TPT (p= 0.02). Additionally, there were greater tick counts in high productivity cows compared to low productivity cows. Conclusions. The abiotic and biotic factors of the ecosystem and animal productivity can affect the TPT counts. In ISS systems, tick counts can be lower than those observed in monoculture grazing systems. Objetivos. Relacionar el efecto de algunos factores bioticos y abioticos sobre las cargas de la garrapata Rhipicephalus (Boophilus) microplus en hembras bovinas que pastorean en sistemas silvopastoriles intensivos (SSPi)(Lucerna) y en monocultivos asociados a cañaduzales (La Isabela). Materiales y métodos. Se realizaron conteos en 27 animales de raza Lucerna en diferentes estados fisiológicos, seis de los cuales se encontraban pastoreando en lotes de gramíneas forrajeras asociados con plantaciones de caña comerciales y los animales restantes pastoreaban en SSPi basados en Leucaena leucocephala y Cynodon plectostachyus. El conteo de garrapatas se efectuó cada 15 días. Los datos de temperatura, humedad y radiación se tomaron de una estación meteorológica que se encontraba en el interior del SSPi. Resultados. Se encontró una relación débil entre el déficit de saturación y los conteos de garrapatas (R2=0.34) y entre la radiación UV y los conteos de garrapatas (R2=0.205) para los bovinos pastoreando en SSPi. Hubo diferencia entre los conteos en animales con similar productividad en ambos sistemas evaluados; siendo el promedio total de garrapatas perceptibles al tacto (GPT) de 311 para La Isabela y de 206 GPT para Lucerna (p=0.02). Hubo mayor número de GPT en hembras con mayor productividad en comparación con las de baja productividad (p<0.05). Conclusiones. Los factores bióticos y abióticos del ecosistema pueden influir en el promedio de GPT, al igual que el nivel de productividad de los animales. En SSPi, la carga de garrapatas puede ser inferior a la de sistemas de pastoreo en monocultivo.