Estrous cycles were synchronized with
2 injections of PGF2ƒ¿ 10 to 14 d apart at the initiation
of the experiment. Thereafter, PGF2ƒ¿ was administered
between d 6 and 18 of the estrous cycle so that 1, 2 to 3,
4 to 6, or .7 cows were in estrus at the same time.