In wintertime 7 nonpregnant cows (3 nonlactating and 4 milk secreting less than 3 liter/day) and 3 heifers were treated:day 1 cloprostenol (530 microgram); day 2 progesterone capronate (0,25/Kg); days 3 to 5 progesterone (0,25 mg/Kg)+ estradiol valerianate (0,01 mg/Kg) and reserpine (0,01 mg/Kg); days 6 to 8 progesterone (0,25 mg/Kg) + estradiol (0,2 mg/Kg) and reserpine (0,01 mg/Kg); day 9 betametasone acetate (0,2 mg/Kg) and phosphate (0,55 mg/Kg); days 9 to 16 estradiol (0,0075 mg/Kg). 9 days later the treatment started again. In all the period (5/12-25/2) the animals where machine milked. 2 lactating nonpregnant cows where kept as control. The milk secretion started in nonlactating animals but the peak daily milk yield was 3 liter about only. In lactating animals the yield no increased. The second treatment (and the first in lactating cows) induced secreting less milk with more fat and protein. The low milk yields was associated to a season's negative effect.