Evidence for a stimulating factor of prolactin and growth hormone secretion present in brewery draff

Aquous extracts of brewery draff injected intravenously into ewes and cows induced prolactin and growth hormone (GH) secretion. The same draff added to the feed of cows appeared to be unable to significantly stimulate the blood level of prolactin and GH. In these experimental conditions, milk production was not enhanced by draff. Pure beta-glucan extracted from barley also stimulated hormone secretion when administered by the intravenous route. Barley, bier and draff therefore contain a beta-glucan-like factor which stimulates lactogenic hormone secretion. The amount present in draff is probably unable to cause an increase in hormones when administered orally. Hence, the well-established stimulatory effect of draff on milk production results from their nutritive value rather than from their ability of modulating the endocrine system.