ABSTRACT
Oestradiol, progesterone, cortisol and reserpine were utilized in treatment regimes for hormonal induction of lactation in dry nonpregnant cows with previous reproductive failures. Lactations were successfully induced in 44 out of 55 cows. The udders of cows in which lactation had been induced successfully were visibly enlarged after 7 days of oestradiol-progesterone treatment on experimental day 8-14 and hence before the administration of cortisol (day 18, 19 and 20). It was concluded that addition of cortisol to oestradiol-progesterone treatment does not improve the success rate of hormonal induction of lactation. The addition of reserpine to oestradiol-progesterone treatment improved the success rate of hormonal induction of lactation. The reduction of oestradiol-17 beta dosage from 60 mg to 30-40 mg day-1 with progesterone at 150 or 200 mg day-1 for the initial 7 days increased both milk yield and the success rate of the hormonal induction of lactation and eliminated pelvic fractures and excessive oestrous activity in treated cows.
