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Endocrinology: the Answer to Seasonal Infertility?

by 5m Editor
28 December 2011, at 10:26am

GLOBAL - For years the annual cycle of infertility has had major implications for the pig industry globally, from indoor producers in Korea to outdoor units in Scotland, writes Stephen Waite, Head of Science at JSR Genetics.

No one has ever touched on a sure fire way to solve this issue, instead like many issues in the pig industry people have focussed on treating the simple, obvious elements in the hope they see a significant improvement on commercial output.


Marmoset monkey

Temperature and light have long been the stalwarts of this thinking, light controlled and air condition boar studs and sow accommodation being the apparent answer. This too was the thinking among researchers looking into many other species, the hope that closely controlling the environment can somehow trick the animal into thinking its winter all the time.

What has being found though, in Marmoset monkeys, is that light and temperature are merely the first breadcrumbs on the trail to what appears to be the true cause of seasonal infertility. It was shown via endocrinology that even sensory deprived monkeys still showed the same reproductive traits as those with normal access to light and temperature, this sparked a study into the actual regulation pathway of fertility. This lead researchers to the hypothalamus in the animals brain, the hypothalamus acts as a so called reproductive clock, by releasing gonadatrophin-releasing hormone (GnRH) in pulses thus controlling the animals reproductive cycle, the pulses are regular over the winter period which is the breeding season and decline over the summer period thus limiting the number of successful ovulations. What was noted was that even in the sensory deprived animals these pulses still lessen over the summer period thus causing infertility.

The control mechanism of these pulses are still not fully understood and may well never be along with the precursors to puberty, but the use of a range of different 'peptins' have been seen to reinstate these pulses in animals. The translation of this work into pigs could have a considerable impact on the industry.

This form of research could also be used to the asses the affect stress has on the reproductive abilities of pigs, as it has been shown that stressors on the animals also affects this pathway in the brain causing ovulation to stop in females and semen production to lower in males.

The Research and Genetics team of JSR will be keeping a close eye on the results of the ongoing research in view of expanding this line of thinking into their current research portfolio.