Mixing of sows and gilts stressful for pigs

Research and developments in pig health, welfare and nutrition are central to driving production and profitability. Sarah Trickett caught up with the latest research developments at a SAC pig research workshop, Edinburgh

The banning of sow stalls and increased mixing of sows and gilts during pregnancy could be having severe and permanent consequences on offspring health and welfare, SAC’s Kenny Rutherford told delegates.

Speaking about his research into prenatal stress effects on welfare and productivity in pigs, Dr Rutherford explained how mixing gilts in the second third of pregnancy was not only stressful for the mixed individuals, but the offspring of those individuals as well.

“The impact of maternal stress during pregnancy on the offspring’s later health and welfare may be overlooked within some farming environments, but it really shouldn’t be and the results show why,” he said.

The results found piglets born to prenatally stressed mothers exhibited a higher pain score during tail docking, weighed about 2kg less three weeks after weaning and were also more stress reactive when mixed at 10 weeks old, indicated by the levels of stress hormones in the blood.

“These behaviours may not be completely apparent as being related to prenatal stress at a farm level, because the offspring’s behavioural outcomes often occur months after the original challenge in the prenatal sow or gilt, but these results clearly demonstrate they are.”

But the knock-on effects go further than the first generation born to prenatally stressed pigs, as Dr Rutherford explained. “We also found when those offspring born from prenatally stressed mothers became mothers themselves, they were more responsive to piglet approach and were therefore more likely to savage.”

Results also found those mothers had significantly higher piglet mortality rates of 32% when farrowing in a loose pen compared to just 10.8% in the same pen for those born to non-prenatally stressed derived pigs.

“This research highlights variation in early life experiences could play a substantial, yet currently hidden role in determining how well farm animals cope with their environment and as such could be a major contributor to poor welfare outcomes,” stressed Dr Rutherford.

He also went on to explain that while such effects were not only damaging to pig welfare, they also presented possible economic costs to individual pig farmers through production inefficiencies.

“From this, farmers really need to put a greater focus on gestation and early life and minimise social stress during pregnancy. This means timing is crucial when sows have to be moved. It’s also important think about other forms of stress in pregnancy such as competition at feeding, poor stock handling and lameness.