|Bohnert, David - OREGON STATE UNIVERSITY|
|Merrill, Missy - OREGON STATE UNIVERSITY|
|Clark, Abe - OREGON STATE UNIVERSITY|
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 17, 2006
Publication Date: June 21, 2006
Citation: Ganskopp, D.C., Bohnert, D., Johnson, D.D., Falck, S.J., Merrill, M., Clark, A. 2006. Effects of early weaning on cow performance, grazing behavior, and winter feed costs in the intermountain west. Western Section of Animal Science Proceedings. 57:121-124. Technical Abstract: Our objective was to determine the influence of early weaning (EW) and traditional weaning (TW) on cow performance and grazing behavior in a 2 yr study. In addition, cow winter feed costs were compared. Each year, 156 cow/calf pairs (78 steer calves and 78 heifer calves) were used in a randomized complete block design. Cows were stratified by calf sex, BCS, and age and assigned randomly to one of two treatments (TRT) and one of three 810-ha pastures. Two cows from each TRT and pasture were fitted with global positioning system collars each year (6 cows/TRT/yr) to evaluate grazing behavior. The EW calves were removed from dams at approximately 130 d, while TW calves grazed with their dams until approximately 205 d of age. All cows were removed from pastures following TW and placed in six separate 25 ha pastures. The same cow groups (blocks) remained intact; however, EW and TW cows were separated and randomly allotted to pastures. All cows were fed to attain a similar BCS (minimum of 5) by approximately 1 mo prior to calving. The TW cows lost 0.8 BCS and 40 kg while the EW cows gained 0.1 BCS and 8 kg from EW to TW (P < 0.01). After winter feeding (approx. 110 d), there was no difference between EW and TW cow BCS (P = 0.52). However, winter feed costs were $29 greater (P < 0.01) for TW compared with EW cows. Grazing time, distance traveled, and number of visits to water were unaffected (P > 0.10) by TRT. However, the proportion of each pasture visited by EW cows tended to be greater than that of TW cows (P = 0.08). Results indicate that EW improves cow BCS entering the winter feeding period, thereby, decreasing winter feed costs. Cow grazing behavior was minimally affected by weaning treatment.