Results and Discussion
It was hypothesized that placing calves in pasture paddocks with trainer cows upon arrival at the feedlot would alleviate stresses associated with adaptation to a new environment. Few attempts have been made to enhance health and performance of newly weaned calves through modification of stress associated behavior. Stookey et al. (1997) conducted a trial comparing remote vs contact weaning (fence-line social contact with dams was allowed). Similar to results presented above, Stookey et al. (1997) reported that there were no long-term benefits on growth rate, however, behavioral indicators of comfort suggested that the well being of newly-weaned calves was improved when they were allowed social contact with their dams. In another trial conducted by these scientists, Schwartzkopf et al. (1997) reported that trainer cows penned with newly arrived feedlot calves altered eating behavior, but not performance and health of the calves.
In our trial, weight gains were lower in the first week than in the remaining three weeks (week effect; P < 0.01) (Table 2). The presence of trainer cows the first 2-weeks did not affect (P > 0.27) gains; however, calves placed on pasture after arrival had lower (P < 0.03) gains during the first week than those housed in the feedlot. This difference did not persist in subsequent weeks. There was an interaction (P < 0.01) between trainer cow status and location for gains during the third week. These effects were residual effects from the previous weeks because during wk 3, all calves were housed in feedlot pens without trainer cows (calves were moved off pasture and cows were removed on day 14). Moving calves to the feedlot and removing the trainer cows resulted in a greater increase in calf gain during week 3 than removing trainer cows from calves previously housed in the feedlot. The reason for this response is unknown. The response is not supported by DM intakes of calves during week 3; previous location and trainer cow status did not affect (P > 0.40) intake during week 3 but did affect (P < 0.01) intake during week 4. Overall morbidity was numerically lower for calves in the feedlot that were housed with trainer cows (most evident during the first 2 weeks before cows were removed. However, the greatest effect on calf health was due to location. Refuting our original hypothesis, calves placed in pasture paddocks upon arrival had more than twice (P < 0.01) the incidence of morbidity vs those placed directly in the feedlot. The increased incidence of morbidity with calves placed in pasture paddocks is difficult to explain, because reducing the stocking rate (area) that calves have is generally related to increased morbidity, and outside environmental stresses are not normally as important as superior air quality in reducing the incidence of respiratory disease (Webster, 1983). Both groups had the same diets delivered to them in feedbunks. Consumption of lower energy pasture and(or) increased movement may have contributed to increased morbidity of calves received on pasture.