Pelley, M. C., Lirette, A., Tennessen, T. 1995. Observations on the responses of feedlot cattle to attempted environmental enrichment. Canadian Journal of Animal Science 75, 631-632.

This study suggests that a so-called enrichment feature will have variable effects on steers depending on how the animals are able to interact with that resource. The straw as environmental stimulus was used the most and produced the most frequent aggression, probably because only one bale of straw was offered to groups of eight animals, who apparently had little choice but compete over this desirable, but limited resource.