PUB - Publikationen an der Universität Bielefeld

The regulation of parental supply and offspring demand was modelled for altricial birds. The situation might differ for precocial species, where offspring can also feed themselves. We investigated the effect of supply and demand on mother-offspring interaction in precocials by cross-fostering pups between the domestic guinea pig and its ancestor, the cavy. The two are closely related, yet guinea pigs are heavier and produce more milk than cavies. We thus created a low-supply situation for pups raised by cavy mothers and a high-supply situation for pups raised by guinea pigs. Females nursing cavy pups confront low demand; those nursing guinea pig pups confront high demand. Pups in a high-supply situation showed more sucking attempts than pups in a low-supply situation, indicating a positive effect of supply on demand. High-demand pups showed more sucking attempts than low-demand pups. Mothers with high-demand pups nursed more frequently and spent more time nursing than mothers with low-demand pups. Milk production remained unaffected and timing of weaning was only slightly adjusted to the kind of pup fostered. Weaning was marked by decreasing of sucking attempts and maternal responsiveness and by increasing aggression. Mothers apparently received information about pup demand, but maternal state seemed to induce the weaning process largely independent of pup demands. The effect of supply on demand differed from predictions of current models. Differences in parent-offspring interaction in altricials and precocials deserve more research attention. (C) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.