Do windbreaks minimize stress on cattle grazing foothill winter range?

Cattle often graze foothill rangelands in northern latitudes as a cost-effective alternative to being fed hay. In a 2-yr study, we determined whether exposure to winter wind elicits a stress response in pregnant cows (5-7 yr old) grazing a foothill rangeland. We measured several indicators of stress-response of cows which had (windbreak) or did not have (non-windbreak) access to windbreaks. In Winter 1 (1966-1997), backfat thickness increased on windbreak and non-wind-break cattle. Body condition scores of both groups were lower at the end of the trial. In Winter 2 (1997-1998), backfat thickness decreased for windbreak and non-windbreak cattle. Body condition scores did not change. Weight changes were minor both winters. Changes in backfat thickness indicated that cattle in Winter 1 were catabolizing more lean muscle tissue, whereas cattle in Winter 2 were catabolizing more fat. Cattle entered Winter 1 in lower body condition and mass than in Winter 2. Cattle with access to windbreaks tended to have a stronger cell-mediated immune response than non-windbreak cattle. Birth and weaning weights of calves, and calving interval were similar for windbreak and non-windbreak cattle. Neither winter elicited a strong stress response from cattle grazing this foothill rangeland, with or without access to windbreaks.