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Abstract
The objective of this research was to evaluate two different strategies to increase the number of artificial insemination (AI) pregnancies in beef herds. The first study evaluated the
impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination
(FTAI) in presynchronized beef cows. Pregnancy rates of cows enrolled in the 7&7 Synch were
compared with pregnancy rates of cows enrolled in a similar protocol combined with an early
progesterone withdraw prior to FTAI. There were no differences in estrus expression and
pregnancy rates between treatments. The second study evaluated the fertility of an early
resynchronization strategy (ER) associated with color doppler ultrasonography (CD). Pregnancy,
conception and cumulative pregnancy rates were compared between cows exposed to natural
service as a second service strategy, and cows exposed to ER and FTAI as the second service
strategy. Early resynchronization resulted in fewer pregnancies compared to natural service as
the second service strategy.