Stanton PhD Thesis final_docx - Atrium - University of Guelph

1.4.3 Social Stressors
Another stressor occurring around weaning is social stress. In studies of mature cattle, it
takes ten days for cattle to establish a social hierarchy (Tennessen et al., 1985). This is a stressful
time for adult cattle and is accompanied by decreased milk yield on the day of mixing. It is
therefore likely that the initial exposure and mixing of calves reared in isolation to new herd
mates is a stressful experience.
Social interactions in established groups are very important to cattle. Operant
conditioning can be used to determine how much value an animal places on certain activities.
Two-month-old calves are willing to work hard to access full social contact with known
conspecifics (Boissy and Le Neindre, 1990; Holm et al., 2002). They still work for nose-to-nose
contact, but place a higher value on full contact as shown by an increased willingness to work for
the reward of social contact. Yearling heifers were trained to access a feed reward either in
isolation, in the presence of conspecifics that they had a strong affinity to, or in the presence of a
conspecific they had a weak affinity towards as measured by social contact prior to testing
(Boissy and Le Neindre, 1990). In order to eliminate competition heifers only had visual contact
with ‘spectator’ heifers during operant testing situations. Results indicate that heifers learn faster
when in the presence of conspecifics, even if they are unable to physically interact with them.
This result was most noticeable when heifers were in the presence of a spectator heifer they had
strong affinity towards. However, heifers trained in the presence of an unfamiliar spectator
animal still learned to access the food reward faster than heifers that were trained in isolation.
These results indicate that social interactions are beneficial for cattle.
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