Synchronizing estrus and(or) ovulation in beef cows after combinations of GnRH, norgestomet, and prostaglandin F2alpha with or without timed insemination.

摘要: Three experiments were conducted to induce estrus and(or) ovulation in 1,590 suckled beef cows at the beginning of a spring breeding season. In Exp. 1, 890 three locations allotted treatments: 1) GnRH on d -7 + prostaglandin F2alpha (PGF2alpha) 0 (Select Synch); 2) PGF2alpha (first day season) plus norgestomet implant (NORG) between and Synch NORG); or 3) two injections given 14 apart (2xPGF2alpha). More (P 60 before onset season, conception rates greater 4, detected < 0.05) = 0.07) increased. 2, 164 treated with Select NORG treatment inseminated either after 16 h second injection (given 48 PGF2alpha). Conception pregnancy tended 0.08) be less 0.05), respectively, for noncycling by appointment, but exceeded 53% both protocols. 3, 536 protocol as 1 either: 54 when also was administered (Cosynch); until h, absence estrus, Cosynch). reduced 0.01) that appointment. An interaction AI cycling status occurred differing results cows. Across experiments, variable proportions various (21 78%) With treatments, induced some normal than those program, particularly inseminations estrus.