Efecto del número de partos, tamaño del cuerpo lúteo y concentración sanguínea de progesterona sobre la tasa de preñez en receptoras de embriones bovinos

Abstract

The research was carried out in Palora, Huamboya, Pablo Sexto and Morona counties in Morona Santiago province. The propounded objective of this study was to determine the pregnancy rate in recipient cows with different number of births, in embryos-transfer (ET) programs. 60 bovine females were selected from the farms of those counties mentioned above. Before starting the treatments, the animals were included in a control program of the estrous cycle by estrus synchronization using progestogens for embryo-transfer at a fixed time. Three categories of recipients were considered: heifers, primiparous cows and multiparous cows. Also, the following determinations were made by ultrasonography: day 0 (estrus), preovulatory follicle size measuring was performed. On day 7 (embryo-transfer), size of the luteum corpus determination was measured and progesterone levels were determined. Additionally, at day 45, a pregnancy test was practiced. It was determined to an overall rate of 65%, the highest rate of pregnancy was for multiparous, second was for primiparous and third was for heifers. Set that the differences between pregnancy rates of the three categories are statistically not significant p>0.005. About the size of the evaluated follicle on the estrus day for pregnant recipients was 16.18 mm and 15.52 mm for non-pregnant, denoting a considerable variability of the size of this structure in non-pregnant rather than in pregnant recipients.