Article

Conducta estral, concentraciones de LH y función lútea en cabras en anestro estacional inducidas a ciclar mediante el contacto con cabras en estro

Veterinaria Mexico 01/1999;
Source: DOAJ

ABSTRACT

El presente trabajo tuvo como objetivo determinar el efecto de las cabras en estro sobre la actividad ovárica de sus compañeras en anestro estacional. Se utilizaron un total de 30 cabras anéstricas divididas aleatoriamente en tres grupos. El grupo I estuvo formado por 10 cabras inducidas al estro con acetato de melengestrol (MGA) combinado con una inyección intramuscular de gonadotropina sérica de yegua gestante (PMSG); el grupo II estuvo formado por 10 cabras no tratadas y mantenidas en contacto directo con los animales del grupo I durante todo el experimento, y el grupo III, formado por 10 cabras sin tratamiento que se mantuvieron alejadas de los otros dos grupos. En todos los animales se detectaron calores diariamente y se obtuvieron muestras de sangre dos veces por semana con el propósito de determinar las concentraciones de progesterona y establecer la presencia o ausencia de ovulación. Además se tomaron muestras de sangre para la determinación de LH cada 2 h desde las 36 hasta las 72 h posteriores a la aplicación de PMSG. Se consideró que un animal tenía actividad ovárica cuando sus valores de progesterona alcanzaron1ng/ml. En el grupo I, el 100% de los animales respondieron con ovulación al tratamiento. En el grupo II el 80% de los animales ovularon en un periodo de 13 días, y en el grupo III, que actuó como testigo, 40% de los animales ovularon. Los picos preovulatorios de LH se observaron a las 54.59 y 64 6 h para los grupos I y II, respectivamente; no se observaron picos de LH en el grupo III. Las diferencias observadas entre los grupos I y II con respecto al grupo III para el porcentaje de presentación de ovulación e inducción 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 ovulación sincronizada en una proporción considerable de cabras en anestro estacional, lo que indica una inducción real de actividad ovárica y no simplemente una conducta de imitación.

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    • "Third, female sexual behaviour may also have influenced the response of other females to the male effect. Indeed, various studies have shown that females in estrus can stimulate other females via the female effect (Walkden-Brown et al., 1993b; Restall et al., 1995; Zarco et al., 1995; Álvarez et al., 1999). In the present study, it is possible that the first females displaying estrous behaviour and ovulatory activity as a result of the male effect may have participated in the stimulation of other does. "
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    ABSTRACT: In seasonally anovulatory goats, daily contact with photostimulated bucks for 15 days stimulates ovulations in most females. In this study, we determined whether ovulation could be induced in goats exposed to photostimulated bucks for less than 15 days. Bucks were rendered sexually active during the nonbreeding season by exposure to 2.5 months of long days from November 1. The control group of females was exposed to one photostimulated buck for 15 days (n = 12). Other three experimental groups were exposed to males (n = 1 per group) for 1, 5, or 10 days (n = 14 or 15 females per group). Ovulations were determined by measurement of daily plasma progesterone concentrations during 17 days. All females from the control and experimental groups ovulated at least once during the experiment (P > 0.05). Furthermore, the proportions of goats that displayed a short luteal phase followed by a new ovulation, or a normal luteal phase after being in contact with males, did not differ between groups depending on the duration of time of contact with the photostimulated males (P > 0.05). In contrast, the proportions of females that displayed a short luteal phase followed by anovulation were greater in goats in contact with males for 1 day than in those in contact with males for 10 and 15 days (P < 0.05), whereas they did not differ from females exposed to males for 5 days (P > 0.05). We conclude that 1 day of contact with sexually active males is long enough to stimulate the ovulatory activity in seasonally anovulatory goats. However, a significantly higher proportion of females exposed to males for 1 day did not ovulate again after showing a short luteal phase. Copyright © 2015 Elsevier Inc. All rights reserved.
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    • "Third, female sexual behaviour may also have influenced the response of other females to the male effect. Indeed, various studies have shown that females in estrus can stimulate other females via the female effect (Walkden-Brown et al., 1993b; Restall et al., 1995; Zarco et al., 1995; Álvarez et al., 1999). In the present study, it is possible that the first females displaying estrous behaviour and ovulatory activity as a result of the male effect may have participated in the stimulation of other does. "
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