Experimental Procedures
Mature cull Simmental X Angus cows served as trainers and were allowed a 3 week pen and diet adaptation period prior to arrival of the newly weaned calves. During the adaptation period, the trainer cows were fed a 60% corn silage, 16% CP feedlot receiving diet (Table 1). Cows were culls from the Coshocton Branch of the Ohio Agricultural Research and Development Center (OARDC). They were culled based on poor production or because they were not pregnant. Cows were transported to the OARDC Feedlot 1 week after the calves were weaned and began the adaptation period immediately upon arrival. Nonpregnant cows were implanted with Synchromate-B (Upjohn Co., Kalamazoo, MI) and given an injection of prostaglandin 3 days before the experiment began to prevent them from coming into heat when they were serving as trainers of the experimental animals. Cows were reimplanted 10 days later.
The experimental animals were crossbred beef steer calves originating from three locations; a Virginia sale barn, and newly weaned calves from the Coshocton Branch of OARDC, or The Ohio State University herd in Columbus. Calves were transported approximately 520, 40, and 95 miles (respectively) to the OARDC feedlot and all calves arrived on the same day. Upon arrival, calves were given a 2-hour rest period during which they had access to hay and water prior to being weighed, ear-tagged, and dewormed with Ivomec (Merck, Rahway, NJ). The purpose of the rest period was to allow the calves an opportunity to eat some hay and drink their fill of water prior to being weighed so as not to have an arbitrarily low starting weight. Calves were vaccinated against IBR, PI3, 7-way Clostridial bacterin, Haemophilus somnus, and Pasteurella upon arrival. Initial and final weights were determined using the average of weights measured on two consecutive days. Interim weights were taken every 7 days, immediately before feeding, to determine weekly performance. The trial was 28 days in duration. The trial was a completely randomized design experiment with a 2 X 2 factorial arrangement of treatments. Factors were trainer cow status (calves housed with or without trainer cows) and placement of calves after arrival (feedlot or pasture). After processing, 216 newly weaned calves were allotted by weight to 24 pens with nine calves per pen. Twelve of these pens contained a previously adapted trainer cow. Immediately after calf allotment to pens, six pens of calves without trainers (54 calves) were grouped and placed in a two acre pasture paddock adjacent to the feedlot. Likewise, six pens of calves with trainer cows were grouped and placed in another two acre pasture paddock. The paddocks were separated by a 200 yard buffer zone. Animals in both groups were moved (after 7 days) to adjacent two acre paddocks (for an additional 7 days) and were then returned to their respective feedlot pens on day 14. Pastures were comprised primarily of orchardgrass which had not been harvested for 30 days prior to the experiment. While located in the pasture paddocks, all animals were offered the feedlot diet ad libitum, in bunks. On day 14, trainer cows were removed from the calves (feedlot and pasture groups) and all pasture calves were returned to their assigned feedlot pens.
Data were analyzed using the GLM procedure of SAS (1988) for a completely randomized design experiment with a 2 X 2 factorial arrangement of treatments. The model contained effects due to trainer cow status, location, and their interaction. The REPEATED statement of SAS (1988) was included in the model to determine effects of time on gain. Assigned allotment pen served as the experimental unit.