摘要：Cognitive challenges may provide a form of enrichment to improve the welfare of captive animals. Primates, dolphins, and goats will voluntarily participate in learning tasks suggesting that these are rewarding, but little work has been conducted on livestock species. We investigated the motivation of 10 pairs of Holstein heifers to experience learning opportunities using a yoked design. All heifers were trained to perform an operant response (nose touch) on a variable interval schedule. Learning heifers then performed this response to access a discrimination learning task in which colour and texture of feed-bin lids signified a preferred reward (grain) vs. a non-preferred reward (straw). Control heifers received the same feed without a choice of bins or association of feed with lid type. Learning heifers approached the target to begin sessions faster (p = 0.024) and tended to perform more operant responses (p = 0.08), indicating stronger motivation. Treatments did not differ in the frequency with which heifers participated in voluntary training sessions. We conclude that heifers are motivated to participate in learning tasks, but that aspects of the experience other than discrimination learning were also rewarding. Cognitive challenges and other opportunities to exert control over the environment may improve animal welfare.
