Evaluación del folículo preovulatorio y efecto del deslorelin como inductor de la ovulación en 12 yeguas silla argentina en el municipio de Facatativá, Cundinamarca

La yegua es considerada una especie poliéstrica estacional, de tal manera que exhibe actividad ovárica máxima durante primavera y verano, y periodos de no actividad en los meses de invierno como respuesta a mayor liberación de melatonina, lo que genera una disminución en la liberación de GnRH y, por lo tanto, de FSH y LH. Aunque bajo condiciones tropicales no se ha observado estacionalidad debido a la poca oscilación del fotoperiodo durante el año, otros factores como la nutrición, temperatura e historia de estacionalidad pueden generar disminución en la actividad ovárica, especialmente en las yeguas importadas desde países lejanos a la línea del Ecuador. Es por esta razón que el proyecto busca ampliar el conocimiento sobre la dinámica de folículos dominantes de 12 yeguas Silla Argentina importadas en el año 2007 por la Policía Nacional de Colombia, realizando un seguimiento ecográfico cada 6 horas de la tasa diaria de crecimiento folicular, a partir de los 35 mm, diámetro máximo del folículo preovulatorio y efecto del análogo de GnRH: Deslorelin, como inductor de la ovulación, mediante la comparación simultánea de dos grupos homogéneos de yeguas: TT 1 tras la aplicación de NaCL, y TT 2 tras la aplicación del Deslorelin. Los datos fueron analizados mediante el análisis de varianza y la prueba T-Student. Se obtuvo como resultado que la yegua de Silla Argentina, en las condiciones de la sabana de Bogotá, tiene un crecimiento diario folicular de 2,24 (+/-0,367) mm/día, aunque no hubo diferencia estadísticamente significativa (P>0,05) con el TT2. El diámetro máximo del folículo preovulatorio fue de 44,39 mm (+/- 1,28 mm). Se encontró diferencia estadísticamente significativa (P

The Mare is considered a seasonal polyestrous species by nature, which means that in terms of latitude, she has several changes in circannual rhythms in the reproduction exhibiting maximum ovarian activities during spring and summer (where there are 15 to 16 hours of light) and periods of no activity in the winter months as a response to greater concentration of melatonin, which generates a decrease in the release of GnRH from the hypothalamus and a subsequent decrease in the levels of FSH and LH, blocking the follicular dynamics. As the FSH levels are very low, these are not enough for the occurrence of the second activation, which is called activation of tertiary or antral follicles. This activation occurs only in the transition and reproductive season, in the particular case of photoperiodic species. Although seasonality has not been observed under tropical conditions due to the little oscillation presented in the photoperiod during the year, other factors such as nutrition, temperature, and history of seasonality may generate changes in the cyclicity of the mare, causing prolonged anestrus periods, especially in the mares imported with a history of seasonality. The introduction of seasonal animals to the different equine production systems in the country generates large economic losses. This is why the project seeks to expand the understanding of the follicular dynamics in the 12 Argentine saddle mares imported in 2007 by the Colombian National Police to Mancilla equine breeding centre. Conducting a follow-up every 6 hours through Transrectal ultrasound which measures the daily rate of pre-ovulatory follicles growth, from the 35 mm diameter until ovulation, the diameter to ovulation and the effect of ovulation inducer Deslorelin by comparing simultaneously two homogenous groups of mares: TT 1 after the application of NaCL, and TT 2 after application of the Deslorelin. The data were analysed using analysis of variance and T-Student test. The results obtained showed that the Argentine saddle mares, under the conditions lived in Sabana de Bogotá, have a daily follicular growth of 2,24 (+/-0,367) mm/day, although there was no statistically significant difference (P > 0,05) with the TT2. The maximum diameter of the preovulatory follicle was 44,39 mm (+/-1,28 mm). Statistically significant difference was found (P < 0, 05) compared with TT2 group, and the interval in hours (application of the Deslorelin - ovulation) was 37 hours (+/-0,68 h). Although 16,6% of the mares did not respond to the inductor, it was statistically significant (P < 0, 05) in comparison to the TT1 group. Even though knowledge and awareness were gained in terms of understanding the follicular dynamics of these mares, this study is the starter of futures researches that involves more knowledge about follicular dynamics in the mare in the tropical conditions.

Medicina Veterinaria