Fertility of cows following superovulation and flushing
Schilling, E.; Haupt, P.; Sacher, B.; Smidt, D.
Deutsche Tierärztliche Wochenschrift 87(8): 289-292
1980
ISSN/ISBN: 0341-6593 PMID: 7006984 Document Number: 164786
168 cows, fed and housed under standardized conditions, were taken at random from two herds. Superovulation was induced between days 40-70 post partum (in some cases as late as 104 days) by the administration of 2500 IU PMSG and of PGF, followed by two inseminations. The uteri were flushed 6-9 days after insemination (60-80 days post partum). Nine cows remained pregnant after the flushing, some even after embryos had been recovered. 157 cows became oestrous at 29 plus or minus 22 days after flushing; the superovulatory cycle lasted for 38 plus or minus 22 days; about half of the cows re-entered oestrus between days 20-28 after superovulation, 15% 50 days thereafter or later. The onset of oestrus was markedly influenced by the management (fertility differences between herds). It was delayed in heifers; and well-reacting animals (more than 8 corpora lutea) had an earlier onset of oestrus than poorly reacting ones (0-2 c.l.). The overall conception rate was 80%; 57% of the cows became pregnant following the second insemination. Heifers conceived 20 days later than older cows; good responders two weeks earlier than poor responders. The season and milk yield had little or no effect on oestrus and conception. In fertile cows, superovulation and flushing, even when timed early in the lactation period, are without adverse effects allowing for a loss of 1.5 cycles. The influences exerted on the fertility rate by the management are more pronounced than those caused by superovulation.