title: Effects of resynchronization strategies for lactating Holstein cows on pattern of reinsemination, fertility, and economic outcome.
abstract: The objectives were to evaluate the pattern of re-insemination, pregnancy outcomes to re-insemination in estrus and at fixed time, and economic outcomes of lactating Holstein cows submitted to three resynchronization protocols. Cows were enrolled in the Experiment at 32 ± 3 d after pre-enrollment Artificial Insemination (AI), 7 d before pregnancy diagnosis, and randomly assigned to three resynchronization protocols. All cows diagnosed not pregnant at 39 ± 3 d after pre-enrollment AI were submitted to the Cosynch72 (Day 0 GnRH, Day 7 prostaglandin F(2α), and Day 10 GnRH and fixed time AI). Cows assigned to the control treatment received no further treatment, cows assigned to the GGPG treatment received a GnRH injection on Day -7, and cows assigned to the CIDR treatment received a controlled internal drug release (CIDR) insert containing 1.38 g of progesterone from Days 0-7. Cows observed in estrus were re-inseminated on the same day. Pregnancy was diagnosed at 39 ± 3 and 67 ± 3 d after re-insemination. Costs of the resynchronization protocols were calculated for individual cows enrolled in the study and pregnancies generated were given a value of $275. The GGPG treatment resulted in the slowest (P ≤ 0.06) rate of re-insemination. Overall pregnancy per AI (P/AI) at 39 ± 3 (P = 0.50) and 67 ± 3 (P = 0.49) d after re-insemination were not affected by treatment. Although cost of the control protocol was (P < 0.01) the smallest, return per cow resynchronized was (P < 0.01) greater for GGPG and CIDR protocols. We concluded that presynchronizing the estrous cycle of cows with GnRH or treating cows with a CIDR insert during resynchronization altered the pattern of re-insemination and improved the economic return of resynchronized cows.
authors.affiliation: Department of Veterinary Population Medicine, University of Minnesota, Saint Paul, Minnesota, USA.
authors.forename: Luís G D
authors.initials: LG
authors.lastname: Mendonça
authors.forename: Steven T
authors.initials: ST
authors.lastname: Dewey
authors.forename: Gláucio
authors.initials: G
authors.lastname: Lopes
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Rivera
authors.forename: Fábio S
authors.initials: FS
authors.lastname: Guagnini
authors.forename: John P
authors.initials: JP
authors.lastname: Fetrow
authors.forename: Todd R
authors.initials: TR
authors.lastname: Bilby
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Chebel
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying / Q000191:economics; D003692:Delayed-Action Preparations; D004973:Estrus Synchronization; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone