Phenotypic Evaluation of Genetic Resistance to the Tick Rhipicephalus (boophilus) Microplus in Argentine Creole Cattle.

The objective of this work was to characterize the Argentine Creole cattle breed through the identification of individual phenotypic variations in the levels of infestation with Rhipicephalus (Boophilus) microplus. We evaluated 179 heifers exposed to successive artificial infestations from 2015 to 2018, achieving a total of 663 observations. Tick counts were assessed with the linear mixed model, considering year of evaluation, time of infestation, dam's age and nutritional status during the evaluated period as fixed effects. The average tick count value obtained allowed to classify the breed as highly resistant to the tick charge (99.3%). Although the previous nutritional condition of the animals did not affect the individual charge response, weight gain during the trial showed a significantly negative correlation. We conclude that the Argentine Creole breed is an attractive genetic alternative for cattle breeding in endemic regions, either as a pure breed or a cross-breed.