EN
Reproduction rate, and litter size in particular, is one of the most economically important aspects of pig production. Progress in researching the porcine genome has enabled polymorphic loci controlling reproduction characteristics in animals to be identified. An example of a gene affecting reproduction is the prolactin receptor (PRLR) gene, which has been mapped to chromosome 16 in pigs. The mechanism through which the PRLR gene affects litter size is not yet known, nor is it known whether the PRLR polymorphism itself causes differences in litter size or whether this polymorphism is a marker for the closely linked major gene for litter size.