PROFILES OF THE HORMONES SOMATOSTATIN, GASTRIN, CCK, PROLACTIN, GROWTH-HORMONE AND CORTISOL .1. IN DAIRY-COWS THAT ARE MILKED AND FED SEPARATELY OR MILKED AND FED SIMULTANEOUSLY

The present study was performed to investigate how the profiles of the gastrointestinal hormones somatostatin, gastrin and CCK, the pituitar y hormones prolactin and GH and the adrenocortical hormone cortisol wa s influenced in dairy cows exposed to two different management routine s: (1) milking and feeding simultaneously, (2) milking and feeding sep arately. Four cows of the Swedish Red and White breed were used. Follo wing separate feeding, the plasma levels of somatostatin, gastrin and prolactin increased, whereas the levels of GH and cortisol decreased. Prolactin was the only hormone that increased significantly in respons e to the milking stimuli, The level of CCK had decreased 20 min after milking. When the cows were milked and fed simultaneously the release of prolactin was larger than during separate milking or separate feedi ng, the release of gastrin was smaller compared with separate feeding and the plasma levels of GH were higher than during separate feeding, It is probable that the release of gastrin was inhibited by somatostat in in this treatment, since the release of somatostatin tended (p < 0. 10) to be larger compared with separate feeding. These results show th at the plasma levels of the studied hormones can be influenced by appl ying different milking and feeding routines. Since these hormones dire ctly or indirectly may be of importance for milk production, the findi ng might have significance for a better management of dairy cows.