The effect of weaning method on coccidial infections in beef calves.

Weaning is often cited as a stressful event that can precipitate clinical coccidiosis in cattle. Recently, two-stage weaning methods have been investigated as a means to reduce stress in calves. The objective of this study was to investigate the effect of weaning method on fecal oocyst count (FOC) and Eimeria spp. composition. A group of 108 beef calves (190-240 days of age) were allocated to three treatments on day -7: a fenceline weaned group where calves could see and hear their dams, but were physically separated from them by a fence (FL), a noseclipped group where suckling was prevented (NC), and a group left with their dams to be traditionally weaned (TW) by abrupt separation on day 0. On day 0, noseclips were removed from the NC calves and all groups were completely separated from their dams. The steers (n=50) were transported 172 km to another farm, and heifers (n=58) were taken to distant fields on the same farm. Rectal fecal samples were collected from all calves on days -7, 0, and 14. Steers were also sampled on days 7, 28, and 42. A group of steers (n=24) from each of the treatments previously described were fitted with pedometers and intensively observed on days 1-4. The Modified McMaster's test and Wisconsin sugar flotation test were used for quantification and identification of Eimeria spp. oocysts. Clinical coccidiosis was not observed during the study. Fecal oocyst counts did not differ between treatment groups on any sampling day. Differences between steer and heifer FOC were not detected. Treatment had no effect on species composition, but time effects were detected in the steers. The mean percentage of E. bovis was lower (P<0.05) on days 28 and 42 than all other sampling days. The decrease in the percentage of E. bovis was accompanied by an increase (P<0.05) in the percentage of E. canadensis on days 28 and 42. Behavioral observation showed that TW steers exhibited higher levels of stress related behavior (P<0.05) following complete separation, although this was not reflected in FOC.