The aim of this study was to evaluate the rate of infection of tick fever (disease caused by agents Babesiabigemina, Babesiabovis, and Anaplasmamarginale, which are transmitted by the tick) in dairy calves supplemented or not with Omnigen-AF (OMN, Phibro Animal Health, Teaneck, NJ) before and after weaning. 120 calves ranked by serum protein (refractometer), evaluated 24–48 h after calving, were distributed to receive OMN (n = 60; 10 g /calf/d up to 60 d, added to milk, and later 20gr/calf/d, added to the concentrate, from 61 to 150 d) or not (CON; n = 60). The calves were kept in individual cages, for 75 d, where they received 6L of milk per day plus ad libitum concentrate. After 75 d, they were introduced into group housing (n = 4), where they received a total mixed ration (TMR). During the experimental period, weekly evaluations were made for blood hematocrit, serum protein, stained smear to detect the presence of Anaplasma spp. or Babesia spp., mucosal color and rectal temperature. The treatment for tick fever (TF) and others disease were recorded daily. Blood samples were collected from the TF treated animals for determination of hematocrit, serum protein, and presence of TF. There was no effect (P > 0.10) of treatment for serum protein parameters, rectal temperatures, and detection of hemoparasites by stained smear. Animals that received OMN in relation to the control group required fewer treatment days for diarrhea and pneumonia (mean of 12.67 vs 15.12 ± 1.1 d, P = 0.1) and for TF (mean of 0.88 versus 1.35 ± 0.13, P = 0.012). OMN group had lower number of animals affected by TF (mean 60% vs 77% ± 6%, P = 0.05), lower number of weeks with hematocrit below normal range (mean of 2.17 vs 3.12 ± 0.32, P = 0.035), lower number of animals that needed to repeat treatment by TF (mean of 0.23 vs 0.37 ± 0.059, P = 0.1), and fewer days of treatment (clinical symptoms) (mean of 0.22 vs 0.4 ± 0.06, P = 0.03). For descriptive statistical analysis it was conducted by the Minitab program (Minitab Inc., State College, PA), generalized linear model, assuming statistical significance for P < 0.05. Omnigen-AF supplementation for dairy calves may minimize infections and clinical symptoms of tick fever.