In Denmark the number of pigs born per litter has been increasing steadily for the past 15 years and has now reached an average of 16.1 pigs per litter. Unfortunately, the number of dead pigs – whether stillborn or dead within the first few days after birth – has also increased. The proportion of dead pigs has been approximately 24 percent of total born piglets in commercial herds during the past six years.
The emphasis on breeding towards larger litter sizes during the period 1992-2004 seems to be a major part of the problem of the high percentage of stillborn pigs and pigs that die within the first few days after birth. The total number of born piglets is phenotypically strongly related to the number of pigs born undersized, weak or underdeveloped. These piglets have an increased risk of dying either during or shortly after birth.
A side effect of large litter sizes is that there are not enough nipples on the sow to provide for all her piglets. In order to solve this problem pig farmers use nursing sows. A nursing sow raises her own litter for three to four weeks after which her pigs are weaned and the sow is given a new litter to raise. This poses welfare problems for the sow because she is penned for a longer period than if she only has to raise her own litter.
Increased monitoring of farrowing can potentially reduce the number of stillborn pigs and neonatal deaths, as can improvements in the pigs’ local environment. The latter practice requires the development of methods that are practical to use. Means such as straw and extra heat sources placed in the right locations in the pen could comprise some of the possibilities.