421 Journal of Animal and Feed Sciences, 13, Suppl. 1, 2004, 421-424 Effects of feeding and cholecystokinin-octapeptide (CCK-8) on the somatotropic axis of goats around weaning Y. Kobayashi 1,3 , M. Onodera 1 , M. Yoshida 1 , P. Guilloteau 2 , K. Katoh 1 and Y. Obara 1 1 Department of Animal Physiology, Graduate School of Agricultural Science, Tohoku University Amamiyamachi, Sendai 981-8555, Japan 2 INRA-UMRVP, Domaine de la Prise 35590 Saint Gilles, France ABSTRACT Post-prandial plasma GH concentrations significantly increased prior to weaning but did not change or decrease after weaning in goats. We hypothesized that this phenomenon was induced by changes in the digestive function or in gastrointestinal hormone secretion at weaning. We therefore gave intravenous administrations of CCK-8 in order to establish whether or not it stimulated GH secretion. The administration in pre-weaned animals increased the GH level, but not ghrelin levels, which were significantly greater than in post-weaned animals. These results suggest that the regulation of somatotropic axis after feeding may be stimulated by peripherally secreted CCK. KEY WORDS: weaning, feeding, growth hormone, cholecystokinin, ghrelin INTRODUCTION Ruminants, prior to weaning, digest milk and absorb nutrients from the intestinal epithelium, but after weaning ruminants digest forages by microbial fermentation and absorb volatile fatty acid (VFA) from the rumen. This means that the digestive function, nutrient metabolism and hormone secretion change around weaning. Cholecystokinin (CCK) release was stimulated by feeding in pre-weaning calves, but it was suppressed after weaning (Toullec et al., 1992). CCK has a number of biological roles at central and peripheral sites: for instance, inhibition of food intake (Gibbs et al., 1973), gastric emptying and intestinal motility (Moran 3 Corresponding author: e-mail: kobayou@bios.tohoku.ac.jp