@article{Silva:8415,
author = "Silva, Manuel Agustín and Abecia Martínez, Alfonso",
title = "{Uso de la combinación de melatonina y prostaglandinas
para la sincronización del estro en ovejas de raza rasa
aragonesa}",
year = "2012",
note = "The goal of this work was to use exogenous melatonin in
combination with PGF2α on spring, to study its efficacy in
the oestrus sinchronization in sheep. Fifty-one female and
4 male Rasa Aragonesa sheep were included in the study.
Ewes were divided in three experimental groups based on the
treatment received. One group was treated with melatonin,
another was treated with melatonin along with a single shot
of PGF2α and the last one was the control group. Rams and
ewes were kept apart until the end of their treatment and
were put together for the breeding. Blood samples from the
female were taken and processed to establish the
concentration of progesterone, in order to know their
reproductive status; these samples were collected seven
days prior to the introduction of males, the day of the
introduction and seven days after the introduction.
Progesterone concentrations showed that 100% of the female
sheep had a cyclical activity before the introduction of
the male sheep. Ewes were in oestrus from the day of
introduction of the male into the pen, and the group
treated with PGF2α showed oestrous sinchronization the
first days of breeding. On day 2, 41% of the individuals
were in heat. The other two groups, the one treated with
melatonin and the control group, showed a fast and growing
sexual activity, which can be attributed to the fact that
the female were already in cyclic stage and to a likely
effect of “sympathy”. Regarding the pregnancy rate, it
is worth noting that it was low (55%) and with no
significant differences among the groups (59% for the group
treated with prostaglandine and 53% in the other two). This
was possibly due to the high number of sheep in heat in a
short period of time which prevented the male sheep to mate
all of them and the stress the animals were subjected
throughout the whole experience. In conclusion, the
combination of melatonin implants and a single shot of
PGF2α in spring showed the capability of sinchronizing the
oestrus in the group treated, although without reaching the
usual figures of the traditional treated with PGF2α and
double shots within 7-10 days.",
}