Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer.
Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer.
Autoria: SIQUEIRA, L. G. B.; TORRES, C. A. A.; SOUZA, E. D.; MONTEIRO JUNIOR, P. L. J.; ARASHIRO, E. K. N.; CAMARGO, L. S. A.; FERNANDES, C. A. C.; VIANA, J. H. M.
Resumo: The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus x Bos taurus indicus) nonlactating cows and heifers (n=259) were treated with the following protocol: 2mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F(2alpha) (PGF(2alpha)) and CIDR withdrawal (Day 8); and 1mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n=90) or in vitro-produced (n=87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P<0.001). Mean (+/-SD) plasma progesterone (P(4)) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2+/-5.0 vs. 3.8+/-2.4 ng/mL; P=0.02). Mean pixel values (71.8+/-1.3 vs. 71.2+/-1.1) and pixel heterogeneity (14.8+/-0.3 vs. 14.5+/-0.5) were similar between pregnant and nonpregnant recipients (P>0.10). No significant relationship was detected between pregnancy outcome and plasma P(4), corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.
Ano de publicação: 2009
Tipo de publicação: Separatas
Unidade: Embrapa Cerrados
Palavras-chave: Corpo lúteo, Echotexture, Ecotextura, Gado de corte, Transferência de embrião, Ultrassonografia
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