Seasonal infertility in pigs: what have we achieved and where are we up to?

The most common manifestations of seasonal infertility are delayed puberty, prolonged weaning to oestrus intervals and a reduced farrowing rate brought about by increased returns to oestrus, including a proportionally higher incidence of irregular returns to oestrus. Over the past 40 years, there has been considerable investment in Australian pig research that has generated extensive knowledge about the physiological mechanisms behind seasonal infertility. While some of the physiological mechanisms allowing the expression of seasonal infertility still remain unclear, a number of possible intervention strategies have been developed and investigated to ameliorate the effects of seasonal infertility in commercial production. For commercial pork producers, there is considerable information available that is based on both research and practical experience, which the farmers can use to identify strategies to minimise the impact of seasonal infertility on the farm. The industry still provides some support to research and development efforts to address seasonal infertility, although, in the future, it may be more targeted to identifying interventions to ameliorate the impact of seasonal infertility in affected herds, rather than undertaking intensive studies into the possible mechanisms and reasons behind this very complex syndrome. [ABSTRACT FROM AUTHOR]