Evaluating the genetic and epigenetic contributions to porcine maternal infanticide and their potential use to identify at risk animals

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Maternal infanticide behaviour towards the newborn has been observed in several mammalian species including mouse, rat, pig and human. There is considerable evidence that this complex abnormal maternal behaviour has an important inherited component but is also influenced by interacting environmental factors.In the pig breeding industry, piglet loss as a result of maternal infanticide has both an economic and welfare impact. From the size of the breeding herds in the UK and Europe (400,000 and 15,000,000 sows respectively - DEFRA estimates in 2007) it is conservatively estimated that 20,000-30,000 piglets are at risk in the UK and 750,000-1,125,000 in Europe at each parity. It would, therefore, be important to use any understanding of the causes of porcine maternal infanticide to reduce the welfare and economic impact in the pig breeding industry.We have been studying porcine maternal infanticide in order to identify regions of the pig genetic material that influence maternal behaviour. These genetic studies have uncovered a number of chromosome segments that carry genes and DNA sequences that may be important in determining this infanticide behaviour. The activity of genes or DNA sequences that regulate genes can be altered either by direct changes in the sequence of DNA (mutation) or by a modification of the DNA that does not alter the sequence but does change its activity; this is known as an epigenetic modification and can be both transmissible and established by interacting environmental factors. In this project we aim to investigate the candidate genes and sequences identified by our genetic studies for evidence of DNA sequences change (mutation) and DNA modification (epigenetic change) to provide direct evidence linking these genes and sequences to the maternal infanticide behaviour. This will be done by comparing the DNA in these candidate regions between affected and unaffected sows. The variations in DNA sequence or DNA modification observed between the two groups of animals may provide the basis for developing predictive tests that could be useful in identifying sows predisposed to maternal infanticide behaviour. We will evaluate this possibility by testing significant differences between affected and unaffected animals on a large collection of animals where we have a well documented record of their maternal behaviour at birth and in the immediate postnatal period. In addition to potentially allowing the design of predictive tests, an improved understanding of the genes, pathways and underlying biology of maternal infanticide in pigs offers routes to the development of possible treatment strategies.