Profiles of the hormones somatostatin, gastrin, CCK, prolactin, growth hormone and cortisol. I. In dairy cows that are milked and fed separately or milked and fed simultaneously

Abstract

The present study was performed to investigate how the profiles of the gastrointestinal hormones somatostatin, gastrin and CCK, the pituitary hormones prolactin and GH and the adrenocortical hormone cortisol was influenced in dairy cows exposed to two different management routines: (1) milking and feeding simultaneously, (2) milking and feeding separately. Four cows of the Swedish Red and White breed were used. Following 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 response 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 feeding, 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 somatostatin in this treatment, since the release of somatostatin tended (p < 0.10) to be larger compared with separate feeding. These results show that the plasma levels of the studied hormones can be influenced by applying different milking and feeding routines. Since these hormones directly or indirectly may be of importance for milk production, the finding might have significance for a better management of dairy cows.