Efecto de la edad a la primera cubrición y de la prolificidad del primer parto sobre la vida útil y productividad numérica en una explotación porcina al aire libre.

Reproductive results of first and posterior reproductive cycles from 535 Large White x Landrace sows were controlled in an outdoor porcine farm. The age at first fertile mating had not significant (P>0.05) on first cycle variables: pregnancy duration, born piglets, born live piglets, born died piglets, weaning piglets, died piglets during lactation and interval weaning –to-conception. The increase of pregnancy duration of gilts reduced significantly (P<0.05) the born piglets. An increasing of weaning piglets number and when the weaning occurred in spring-summer tended (P<0.10) to increase the interval weaned-to-conception. Values of the age at the first fertile mating ≥ 311 days reduced significantly the reproductive cycles number that the sows accomplished in the farm (useful life), while values >291 days decreased significantly the average annual numerical productivity per present sow. A significant increase of average annual productivity with the useful life was observed. The useful life of the sows was significantly higher when in their first farrowing the number of born alive piglets was > 10. The average annual numerical productivity increased with the prolificacy of the first litter. It is concluded that is interesting advance the age at the first mating of the gilts, and that the prolificacy obtained in the first litter can help to producers to decide the replacement and removal of sows. [ABSTRACT FROM AUTHOR]