Topigs: Sows in groups produce heavier piglets
Reproductive data of more than 40,000 Topigs sows from 59 Dutch farms in the period 2008-2009 show that group-housed sows produce piglets with an average birthweight 61 gram higher than those of individually housed sows.
These results are confirmed by various scientific papers.
Welfare regulations mean that from 2013 onwards, sows in Europe must be housed in groups during gestation. These group housing systems allow sows to interact socially and perform behavioural patterns that might benefit their welfare, decrease stress levels and thus positively influence birthweight.
Another possible explanation for the higher birthweights is that group-housed sows exercise more than individually housed sows. Researchers found that sows who exercised a lot during gestation had higher birthweights than sows who exercised little. This could be related to a better blood circulation of the uterus.
A third explanation might be that group-housed sows lose less body energy through radiation in cold seasons as they can huddle together and sometimes straw is used as an insulating material on the floors.