Comportamiento durante el calor y dinámica folicular interestral en vacas BON (Blanco Orejinegro)

Abstract

ABSTRACT: The Colombian criollo cattle are at risk of extinction. One of these breeds, the BON (Blanco Orejinegro: White black-eared) is characterized by its resilience in spite of the rough managerial practices to which it is usually subjected; additionally it is said that these animals are resistant to diseases such as FMD, which has been corroborated in vitro and associated with the capacity of the cells to produce type I Interferon. We are interested in the propagation and the preservation of this breed through biotechnological methods, which requires a broad and deep knowledge of their reproductive physiology and behavior. The objective of this project was to characterize its follicular dynamics and the estral behavior. Using seven non-lactating regularly cycling cows with 2-7 previous parturitions. These animals were under traditional management, grazing on Cynodon nlefuensis, Brachiaria decumbens and native grasses. Daily ultrasonography was practiced during two consecutive cycles for each cow and 30 minute observation intervals thrice a day were carried out at 7am, 2 pm and 5pm. Cohorts of follicles were detected starting at 3 mm, with growth rates of 0,04 mm/day up to the moment of divergence. After this moment the growth rate of the subordinate follicles was 1,1 and that of the ovolulatory follicle changed from 13.5 to 17.6 mm. The interval between ovulations was 23-25 days and the number of follicular waves was 3 or 4 with a dominance of 3-6 days.

RESUMEN: El ganado criollo BON ha sido categorizado como ""vulnerable"" y se ha recomendado su propagación a través de procedimientos biotecnológicos, lo que requiere, en principio, conocer su fisiología reproductiva. El objetivo del presente trabajo es contribuir a dicha meta mediante la caracterización del comportamiento folicular ovárico durante el ciclo estral. A siete vacas horras, ciclando regularmente, con condición corporal entre 3 y 3.5, y con 2 a 7 partos, pastoreando Estrella (Cynodon nlemfuensis), Brachiaria decumbens y gramas nativas del género Paspalum, se les practicó seguimiento ultrasonográfico diariamente durante dos ciclos estrales. La detección de calores se realizó mediante tres observaciones diarias, cada una de 30 minutos (7 am, 2 pm y 5 pm). Se detectaron cohortes de folículos a partir de 3 mm, con tasas de crecimiento (TC) de 0.04 mm/día hasta la divergencia; a partir de ese momento la TC de los folículos subordinados fue de 1.1 y la del dominante de 2.1 mm/día; el diámetro de éste último folículo osciló entre 10 y 23 mm y el del folículo ovulatorio varió entre 13.5 mm y 17.6 mm. El intervalo entre ovulaciones fue de 23 a 25 días con tres a cuatro ondas foliculares y dominancias de 3-6 días.