22 research outputs found
Synchronization of estrus in yearling beef heifers with the MGA®/prostaglandin system: I. effect on inducement of puberty and conception rates
We evaluated the estrous response and
fertility of yearling beef heifers after treatment
with melengestrol acetate (MGA) and prostaglandin
F2" (PG). The 304 heifers, at three
locations, were allotted to two treatments:
nonsynchronized controls and those receiving
.5 mg MGA per head daily for 14 days followed
by a 25 mg PG injection 17 days after
the end of MGA feeding (MGA/PG). Heifers
in the control and MGA/PG groups were
artificially inseminated 12 hours after observed
estrus for 21 days or 6 days after PG, respectively.
Conception rate at first service and
overall pregnancy rate did not differ (P>.10)
between MGA/PG and control heifers (64%
vs. 50% and 49% vs. 38%, respectively).
However, the MGA/PG system effectively
induced puberty and synchronized estrus,
allowing more (P<.009) heifers to become
pregnant early in the breeding season (49%)
compared with nonsynchronized controls that
were inseminated on spontaneous estrus
(14%)