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Abstract
Twenty-four heifers in were synchronized for estrus using a 7-day CIDR protocol with 2 injections of PGF2, one at CIDR removal and one 16 hours later. All animals were calf-hood vaccinated with an available BRDC vaccine with a MLV IBR component. At Heat 2, heifers were vaccinated with either the same MLV IBR or a BRDC vaccine with a Killed IBR component. There was no significant effect of vaccine on P4 concentrations, E2 concentrations, estrous cycle lengths or first service conception rates (P>0.05). There was a decrease (P<0.05) in circulating AMH concentrations from Cycle 1 to 2 and 1 to 3, but there was no difference (P>0.05) between vaccine types. There was no vaccine difference (P>0.05) between post-vaccination titers, circulating white blood cell concentrations or neutrophil activity.