Effects of adrenalectomy upon ruminant liver and mammary function during lactation

Adrenalectomized, lactating ewes treated with a mineral corticoid or a mineral corticoid plus cortisol and sham operated ewes nursing one or two lambs were in a study of physiological role(s) of glucocorticoids in lactating ruminants. Measurements of ewe and lamb weight changes; feed intake; milk yield and composition; blood potassium; metabolite oxidation rates by mammary, liver, and kidney tissue slices; glucose production in liver and kidney tissue slices; and enzyme activities in mammary and liver tissue. 1) Mammary metabolism and milk biosynthesis in ruminants are not strongly dependent on glucocorticoid. 2) Liver gluconeogenesis in ruminants appears to be regulated in part by glucocorticover and kidney of ruminants may respond differently to adrenalectomy; thus, in ruminants, kidney may not be as good an indicator of liver gluconeogenic responses as it is in rodents. 4) Liver and mammary enzymes are not affected significantly by adrenalectomy or glucocorticoid therapy. 5) Glucocorticoids play a less significant role in the regulation of liver and mammary enzyme and metabolism in sheep than in rats.