Influence of Adrenocorticotropin upon Milk Production, Milk Constituents, and Endocrine Measures of Dairy Cows

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Abstract
Ten lactating Holstein cows were injected i.m. with either 200 IU of ACTH or saline every 6 h for 42 h. Blood concentrations of corticosteroids, glucose, Na and K and milk yield and constituents were measured before, during and after the injection period. Mean corticosteroid increased 8-fold for ACTH 1 h after 1st injection, remained significantly higher than controls during the injection period, and then decreased to preinjection concentrations 13 h after last injection. Mean milk yields were similar at 8 h after 1st injection, then decreased for ACTH during the injection period. Increases in glucose concentrations accompanied suppression of milk yield for ACTH. After injections glucose concentrations returned to preinjection concentrations at 13 h after last injection; milk yield for adrenocorticotropin remained suppressed for several milkings. Milk protein yields decreased for ACTH during and after the injection period. Fat percentage for ACTH increased though fat yield was unaffected. Concentrations of somatic cells in milk were unchanged by ACTH treatment, but Na was increased and K decreased during injection. Mammary gland function in lactating dairy cows may be affected adversely by exaggerated increases of concentrations of corticosteroids in blood.