Fertility of cows after superovulation and subsequent flushing of uterus

Return of cow donors into further reproduction was studied after their superovulatory treatment and flushing of embryos. 122 cows at the age 3-9 years, of Slovak Pied, Pinzgau, Holstein-Friesian breeds and their crosses were included in this experiment. The cows were superovulatory treated with preparations FSH-P (Burns-Biotec, USA - n=64), and Folicotropin Spofa (Leciva Prague, CR - n=58). The preparations were applied over 4 days in a series of 8 injections, at 12 hour intervals, the total dose being 50 mg and 24 mg, respectively. The beginning of stimulation was on 9th - 12th day of sexual cycle. PGF2 alfa (Oestophan Spofa Leciva Prague) was administered in a dose of 500 micro g in the morning and 250 micro g in the evening 48 hours after the beginning of application. The donors remained in the herd after the flushing of uterus. The term of oestrus occurrence, rate of pregnancy after 1st - 4th insemination, and the influence of the interval between calving and embryo recovery on time and success of insemination after returning into normal reproduction were studied. The influence of the superovulatory preparations on total pregnancy after 4 inseminations was also studied. The donors were divided into 4 groups according to the interval of calving - embryo recovery: A group (flushing to 60 days after calving), B group (61-80), C group (81-100), and D group (over 100 days). 109 out of 122 donors were pregnant after superovulation and flushing, i.e. 89.34 % on average at 64.20 days after flushing, with 147.93 days service period. 90.90 % donors were pregnant on average in group A (n=11) at 45.30 days, with service period (SP) 97.50 days, 92.31 % donors were pregnant in group B (n=39) at 54.16 days, with SP 125.16 days, 86.00 % donors were pregnant in group C (n=50) at 54.16 days, with SP 115.16 days and 90.90 % donors were pregnant in group D (n=22) at 72.30 days, with SP 189.70 days. The most donors became pregnant in groups A and B (63.63 % and 61.53 %) in 37.28 and/or 44.00 days after embryo recovery, with the service period 88.71 and 115.16 days after 1st insemination. No marked differences (90.63 % vs. 87.93 %) were observed during the evaluation of pregnancy after no more than 4 inseminations with the use of FSH-P USA and FSH Spofa. The results show that superovulatory treatment and recovery of embryos do not harm further reproduction of donors. From the viewpoint of economy it is necessary to superovulate the cows to the 80th day after calving.