Estrous behaviour, LH concentrations and luteal function in seasonally anestrous goats exposed to herdmates in estrous

• Published in: Veterinaria Mexico (Mexico) Vol. 30; no. 1
• Main Authors: Alvarez Ramirez, Lorenzo, Ducoing Watty, Andres E, Zarco Quintero, Luis A, Trujillo Garcia, Abel M
• Format: Journal Article
• Language: Spanish
• Published: 01.03.1999
• Subjects: CAPRIN; CAPRINOS; CICLO ESTRAL; CORPS JAUNE; CORPUS LUTEUM; CUERPO LUTEO; CYCLE OESTRAL; GOATS; OESTROUS CYCLE; PROGESTERONA; PROGESTERONE
• ISSN: 0301-5092

The purpose of this study was to establish the effect of estrous goats on the ovarian activity of their seasonally anestrous herdmates. Thirty adult female goats were studied during the anestrous season, and were randomly divided in three groups: Group I was formed with 10 goats that were induced to estrous using melengestrol acetate (MGA) and pregnant mare serum gonadotrophine (PMSG); Group Il included 10 goats without any treatment but maintained in direct contact with the animals of Group 1 during the time of the experimental trial, and Group Ill, formed with 10 goats that were untreated and mantained away of the other 2 groups. Estrous detection was carried out daily, and blood samples for progesterone determination were taken twice per week in order to assess the occurrence of ovulation. Besides, blood samples for LH determination were taken in all animals every 2 h from 36 to 72 h after the injection of PMSG to animals in Group l. Ovulation was considered to have occurred when progesterone concentrations were increased above 1 nglml. All goats in Group I ovulated after the hormonal treatment, whereas 80% of the goats in Group II and 40% of those in Group Ill ovulated during the following 13 days. The value in Group III was significantly lower (PO.05) than that in Groups I and II. Preovulatory peaks of LH were observed in Group 1 at 54.5 9 h and in Group II at 64 6 h after the end of the treatment of Group l. No peaks of LH were observed in Group Ill. Data obtained in this study indicates that goats in estrous are capable of inducing estrous, preovulatory peaks of LH and synchronized ovulation in seasonally anestrous goats. Thus, this is a real induction of ovarian activity and not a simple imitation of behaviour El trabajo tuvo como objetivo determinar el efecto de las cabras en estro sobre la actividad ovarica de sus companeras en anestro estacional. Se utilizaron un total de 30 cabras anestricas divididas aleatoriamente en 3 grupos. El grupo I estuvo formado por 10 cabras inducidas al estro con acetato de melengestrol (MGA) combinado con una inyeccion intramuscular de gonadotropina serica de yegua gestante (PMSG); el grupo II estuvo formado por 10 cabras no tratadas y mantenidas en contacto directo con los animales del grupo 1 durante todo el experimento, y el grupo 111, formado por 10 cabras sin tratamiento que se mantuvieron alejadas de los otros 2 grupos. En todos los animales se detectaron calores diariamente y se obtuvieron muestras de sangre 2 veces por semana con el proposito de determinar las concentraciones de progesterona y establecer la presencia o ausencia de ovulacion. Ademas se tomaron muestras de sangre para la determinacion de LH cada 2 h desde las 36 hasta las 72 h posteriores a la aplicacion de PMSG. Se considero que un animal tenia actividad ovarica cuando sus valores de progesterona alcanzaron Ing/ml. En el grupo 1, el 100% de los animales respondieron con ovulacion al tratamiento. En el grupo 11 el 80% de los animales ovularon en un periodo de 13 dias, y en el grupo III, que actuo como testigo, 40% de los animales ovularon. Los picos preovulatorios de LH se observaron a las 54.5 9 y 64 6 h para los grupos I y Il, respectivamente; no se observaron picos de LH en el grupo 111. Las diferencias observadas entre los grupos 1 y 11 con respecto al grupo 111 para el porcentaje de presentacion de ovulacion e induccion de estros fueron significativas (P 0.05). Se concluye que la presencia de cabras en estro es capaz de inducir el estro, picos preovulatorios de LH y ovulacion sincronizada en una proporcion considerable de cabras en anestro estacional, lo que indica una induccion real de actividad ovarica y no simplemente una conducta de imitacion.