Numerous
estrous synchronization protocols using PGF, GnRH,
and(or) a progestin have been developed that induce
cyclicity and successfully synchronize estrus in suckled
beef cows [5,6,13]. In this study, 57% of cows exhibited
estrus at or before AI, which was lesser than the previous
studies [7,14]. Cyclicity of cows in this study ranged from
38% to 71% at 12 locations. The previous studies indicate
that there is large variability in the proportion of cycling
females among beef cattle operations at the beginning of
the breeding season