Variability in pig units: description and on-farm implication

Abstract

Pig breeders can cope with variation in sow prolificacy as long as the total number of piglets born alive does not exceed the total number of functional teats of the sows in the farrowing unit. Cross-fostering allows adjusting the size of the litter to the milk production potential of the sow. When prolificacy increases, this objective becomes more difficult to achieve. In addition, the within-litter variation of birth weight increases with prolificacy, compromising the survival chance of small piglets. Short-term solutions can be obtained by providing additional care around birth, by grouping of pigs of similar body weight and by providing appropriate feeding strategies. Nevertheless, variability is still observed at the end of the fattening period. This results in difficulties to find the best slaughtering strategy, especially when the economic return depends on a payment grid that is based partly on carcass weight. Although genetic selection may eventually reduce the variation in performance in sows and piglets, feeding strategies that account for the individual requirement of the gestating sow can already be used to improve the farrowing process. Although this helps to improve piglet vitality at birth, to date, it is not effective in reducing within-litter variation in birth weight. Most of these improvements have been reported for sows and piglets kept in experimental facilities. It remains a challenge to obtain these results in production units.