Infestação por Rhipicephalus (Boophilus) microplus em novilhas de diferentes grupos genéticos

An assessment of the infestation of ticks Rhipicephalus (Boophilus) microplus in 59 heifers of three genetic groups was run: Nellore, Guzera and ½ Angus x ½ Nellore, belonging to the roster APTA Regional Andradina / SP. Every 28 days held the count of ticks, where the left side of the animal, with evaluation of only engorged females with more than 4.5 mm in the period from June 2007 to May 2008. The genetic group (P 0.05). The count of ticks was higher in the rainy season (4.32 ± 5.20) in comparison with the dry season (3.74 ± 5.54). Despite the higher counts of ticks during the experimental period, in heifers ½ Angus x ½ Nellore, this genetic group obtained the highest average daily weight gain (0.57 kg/day). Heifers and bulls Nellore and Guzera were not statistically different in relation to daily weight gain, with averages of 0.37 and 0.40kg/day, respectively. ½ Angus heifers genetic group cattle have a higher infestation by ticks.