[Plasma progesterone concentrations and embryo yield in superovulated cows under tropical conditions in the state of Yucatan in Mexico] | Concentracion plasmatica de progesterona y produccion embrionaria, en vacas superovuladas bajo condiciones tropicales

English. This study was carried out in three ranches in the state of Yucatan, Mexico. The objective was to study the relationship between plasma progesterone (p4) concentration at the beginning of the superovulatory treatment, at estrus and at the embryo collection day studying both the ovary response and embryo yield. Eleven days after oestrus, 30 cows were superovulated with the follicle stimulating hormone (FSH-P) and embryos were non-surgically collected 7 days after insemination. Cows with a plasma psub4 concentration above 3 ng/ml at the beginning of the superovulation presentes a major number of corpora lutea (CL: 12.4 vs. 10.2; P 0.05), total ova and embryos (TOE: 9.3 vs. 4.7; PO.Ol) and transferable embryos (TE: 6.6 vs. 3.0; PO.Ol) than animalswith -3 ng/ml. All cows showed estrus after the PGF 2alpha injections. Animals a with a Psub4 concentration -1 ng/ml at estrus produced more TOE (6.9 vs. 3.0) and TE (4.6 vs. O.O), than the ones with a P4 concentration 1 ng/ml. Animals with 11 ng/ml of the p4 concentration at day of embryo collection presented a higher number of CL (1 5.5 vs. 10. 5; P0.05), TOE (10.0 vs. 5.9; P0.05) and TE(7.9 vs. 4.6; P 0.05) than cows with a lower plasma p4 (-11 ng/ml) concentration. It was concluded that cows with a plasma p4 concentration above 3 ng/ml at the beginning of the superovulation, -1 ng/ml at estrus and with 11 ng/ml on the day of embryo collection, had a better response after the superovulatory treatment and produced more embryos. Under tropical conditions, a plasma p4 concentration prior to the beginning of the superovulatory treatment can be used as a basis to select donor cows with a greater potential response

Spanish; Castilian. El presente estudio se realizo en condiciones de campo en tres ranchos de la zona centro del estado de Yucatan. El objetivo fue relacionar la respuesta ovarica y la produccion embrionario con la concentracion plasmatica de progesterona (p4 ) al dia de inicio de la superovulacion, al estro, y al dia de la recoleccion embrionario. Para ello, 11 dias despues del estro se superovularon 30 vacas con hormona foliculoestimulante (FSH-P) durante 4 dias, a dosis decrecientes. La recoleccion embrionario se efectuo 7 dias despues de la primera inseminacion. Las donadoras con concentracion plasmatica de p43 ng/ml al iniciar la superovulacion, tuvieron mayor promedio de cuerpos luteos (CL: 12.4 vs. 10.2; P0.05); total de ovulos y embriones (TOE: 9.3 vs. 4.7; P0.01) y embriones transferibles (ET: 6.6 vs 3.0; PO.Ol) que las vacas con -3 ng/ml. Las donadoras con concentracion plasmatica de P 4 -1 ng/ml al estro, produjeron mas TOE (6.9 vs. 3. O) y ET (4.6 vs. O. O) que las vacas con 1 ng/ml de P 4 Las vacas con 11 ng/ml de P 4 al dia de la recoleccion embrionario tuvieron mayor promedio de CL (15.5 vs. 10.5; PO.05), TOE (10.0 vs. 5.9; P0.05) y ET (7.9 vs. 4.6; P0.05) que las donadoras con menor concentracion plasmatica de P4 (-11 ng/ ml). Se concluye que las donadoras con concentracion plasmatica de P4 3 ng/ml al iniciar la superovulacion, -1 ng/ml al estro y 11 ng/ml al dia de la recoleccion embrionario, presentaron mejor respuesta superovulatoria y produjeron mas embriones. Bajo condiciones tropicales, la concentracion plasmatica de progesterona, antes del inicio de la superovulacion, puede ser utilizada como un indicador para seleccionar a las donadoras con mayor rendimiento potencial