Popular sire effect

rdf:langString Popular sire effect

rdf:langString The popular sire effect (or popular stud/sire syndrome) occurs when an animal with desirable attributes is bred repeatedly. In dog breeding, a male dog that wins respected competitions becomes highly sought after, as breeders believe the sire possesses the genes necessary to produce champions. However, the popular sire effect is not just down to wanting to produce a champion. For example, in Staffordshire Bull Terriers there are several popular sires who are used by breeders to produce specific colours that are not favoured in the show ring. The popular sire is often bred extensively with many females. This can cause undetected, undesirable genetic traits in the stud to spread rapidly within the gene pool. It can also reduce genetic diversity by the exclusion of other males. While a popular stud can sire a large number of litters, the effect of a popular dam is more limited. The constraints of the female reproductive cycle requires dams to have several months in between each litter so, even at capacity, a dam would not be able to parent as many offspring as a sire; furthermore, a dam bred repeatedly may experience a sharp decline in her litter count due to a weaker body caused by too many consecutive pregnancies.