Revista Veterinaria Zacatecas 2006 - Universidad Autónoma de ...
Revista Veterinaria Zacatecas 2006 - Universidad Autónoma de ...
Revista Veterinaria Zacatecas 2006 - Universidad Autónoma de ...
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M T Rivera-Lozano et al<br />
libera en las horas oscuras <strong>de</strong>l día. En la<br />
temporada <strong>de</strong>l año con mayor período <strong>de</strong><br />
secreción diaria <strong>de</strong> melatonina, como ocurre en el<br />
otoño e invierno, <strong>de</strong>bido al incremento <strong>de</strong> las<br />
horas oscuras <strong>de</strong>l día, la hormona disminuye la<br />
retroalimentación negativa <strong>de</strong>l estradiol sobre el<br />
hipotálamo, lo cual permite la presencia <strong>de</strong> ciclos<br />
estrales en esta parte <strong>de</strong>l año. La influencia <strong>de</strong>l<br />
fotoperiodo sobre la estacionalidad varía <strong>de</strong><br />
acuerdo a la zona geográfica don<strong>de</strong> se encuentren<br />
los animales, las cabras son más estacionales en<br />
los hemisferios que al nivel <strong>de</strong>l Ecuador. Sin<br />
embargo, las hembras <strong>de</strong> la zona tropical que se<br />
trasladan a latitu<strong>de</strong>s más elevadas y se mantienen<br />
bajo fotoperiodos característicos <strong>de</strong> la región<br />
templada manifiestan estacionalidad reproductiva,<br />
como lo hacen las cabras <strong>de</strong> esa región. El macho<br />
sexualmente activo pue<strong>de</strong> inducir la ovulación y la<br />
manifestación <strong>de</strong>l celo en animales en anestro.<br />
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