Effect of prepartal hormone administration on feed intake and mineral metabolism of cows.

Subcutaneous administration of progesterone (.25 mg/kg body weight per day) to mature cows from 14 days before projected parturition until parturition increased feed intake over control cows. Incidence of milk fever and plasma calcium, phosphorus, magnesium, and hydroxyproline were not significantly different between treated and control cows. Subcutaneous administration of estradiol-17beta (.05 mg/kg body weight per day) or oral administration of melengestrol acetate (1 mg/day) from 7 days before projected parturition date until parturition decreased feed intake over control cows. Milk fever incidence and absorption of calcium, phosphorus, and magnesium were not significantly different between treatment groups. Plasma calcium was not significantly different between treatment groups during either the prepartum or postpartal periods but tended to be higher postpartum in cows treated with estrogen.