title: Effect of the time of artificial insemination with frozen-thawed or fresh semen on embryo viability and early pregnancy rate in gilts.
abstract: The aim of the present study was to evaluate the effect of artificial insemination time (before or after ovulation) using either fresh or frozen-thawed boar semen on embryo viability and early pregnancy rate. Seventy-seven prepubertal crossbred (Landrace x Large White x Duroc) gilts were inseminated in 4 treatments. Artificial inseminations were performed 6 h either after (A) or before (B) ovulation using frozenthawed (A-frozen, n = 19; B-frozen, n = 19) or fresh semen (A-fresh, n = 21; B-fresh, n = 18). The gilts were induced to puberty by administration of 400 IU of eCG and 200 IU hCG (sc) followed by 500 IU of hCG (sc) 72 h later. Ovulation was predicted to occur 42 h after the second injection. All animals were slaughtered 96 h after AI. Embryos were collected and classified as viable (5- to 8-cells, morulae, compacted morulae and early blastocysts) and nonviable (fragmented, degenerated and 1- to 4-cell embryos). The total embryo viability rate was: 64.3% (A-frozen), 54.2% (A-fresh), 76.0% (B-frozen), 91.9% (B-fresh); (A-fresh vs B-fresh, P = 0.018; A-frozen vs B-frozen, P = 0.094). It was observed that AI before ovulation resulted in a higher percentage of total viable embryos than AI after ovulation (P = 0.041). The early pregnancy rate, defined as presence of at least one viable embryo, was 78.9, 80.9, 84.2 and 94.4% for A-frozen, A-fresh, B-frozen, B-fresh, respectively. There was no significant difference in the early pregnancy rate among groups. In conclusion, there was a detrimental effect upon total embryo viability rate when AI was performed after ovulation with either frozen-thawed or fresh semen. The total embryo viability rate and the early pregancy rate were not affected by AI with either frozen-thawed or fresh semen regardless of the time of AI.
authors.affiliation: National Research Center for Swine and Poultry, CNPSA/EMBRAPA Cx. Postal 21, 89.700-000 - Concórdia - SC, Brazil.
authors.forename: G R
authors.initials: GR
authors.lastname: Bertani
authors.forename: I R
authors.initials: IR
authors.lastname: Scheid
authors.forename: F B
authors.initials: FB
authors.lastname: Fialho
authors.forename: M I
authors.initials: MI
authors.lastname: Rubin
authors.forename: I
authors.initials: I
authors.lastname: Wentz
authors.forename: P B
authors.initials: PB
authors.lastname: Gonçalves