Calves' motivation for access to two different types of social contact measured by operant conditioning

Calves housed individually have little opportunity for social contact. However, performance of social behaviour may constitute a need in calves. Slopes of demand functions (demand elasticity), generated by operant conditioning techniques, are used to measure. behavioural motivation of farm animals. A methodological discussion concerns the way social contact should be provided in operant conditioning studies. By operant conditioning, the present study investigated calves' motivation for two different types of social contact: head contact through metal bars, and full social contact where calves were allowed to interact without restrictions. Six test calves and six companion calves were used. Tests were carried out in daily sessions in a cross-over design. For each treatment, test calves were exposed to five Fixed Ratio schedules (FR6; 12, 18, 24, 30) within three runs. Rewards consisted of 3 min access to social contact with the companion. Behavioural activity in the reward periods was recorded continuously. Results showed a difference between demand functions based on number of rewards obtained per session. The slope for head contact was steeper than for full contact (P < 0.01), whereas intercepts did not differ. Calves used more time for social activity within rewards when tested for full contact compared to head contact (P < 0.001). Duration of social activity per reward increased as a function of increasing FR value for full contact (P < 0.001), but not for head contact. Calves used significantly less time for social activity in the later rewards of the test sessions compared to the earlier for full contact (P < 0.01), but not for head contact. Slopes of demand functions based on duration of social activity per session were not significantly different, but intercepts differed significantly (P < 0.01). For both head and full contact, lopes were more shallow than slopes of demand functions based on number of rewards. The study shows that the type of social contact may influence the slope of the resulting demand function based on number of rewards obtained per session. Calves are more motivated to get access to full contact than to head contact, and therefore, full contact should be used in future operant conditioning studies. Moreover, the study also shows that factors like FR value and reward number may affect the duration of time actually engaged in social activity within rewards when full social contact is used as reinforcer. (C) 2002 Elsevier Science B.V. All rights reserved.