Way Found to Gauge Pig's Happiness
Rodents and pigs have individual personalities, research has shown.
Credit: Left: USDA/Keith Weller; Right: Dreamstime.com

Pigs have feelings, too. And a new study reveals a way to ask a pig if it's happy or not, and get an answer.

"Our research, for the first time, provides an insight into pigs' subjective emotional state and this will help scientists and farmers to continue to improve the lives of their pigs in the future," said study researcher Sandra Edwards, professor of agriculture at Newcastle University in England and one of the U.K.'s leading experts in pig welfare.

The research results were announced today.

Pig talk

Edwards and team leader Catherine Douglas, also of Newcastle, used a technique to "ask" pigs if they are feeling optimistic or pessimistic about life as a result of their surroundings.

To do this, the researchers taught the pigs to associate a musical note on a glockenspiel (instrument similar to the xylophone) with something pleasant (an apple treat) and a clicker used for dog training with something unpleasant – the rustling of a plastic bag.

Then, half of the pig participants were placed in an enriched environment with lots of space and freedom to roam in straw and play with pig toys. The other pigs landed a smaller, less stimulating pad with no straw.

The team then played an ambiguous noise – a squeak – and monitored the pigs' responses.

"We found that almost without exception, the pigs in the enriched environment were optimistic about what this new noise could mean and approached expecting to get the treat," Douglas said. "In contrast, the pigs in the boring environment were pessimistic about this new strange noise and, fearing it might be the mildly unpleasant plastic bag, did not approach for a treat."

A similar phenomenon is found in humans, Douglas said, in which our mood affects our judgments of ambiguous events. So if you're feeling stressed and down and your boss calls into your office, your first response might be to fear you've done something wrong. That same call could elicit a positive reaction on a good day.

"This 'glass half empty versus glass half full' interpretation of life reflects our complex emotional states, and our study shows that we can get the same information from pigs," Douglas said.

Animal welfare

The study is part of ongoing research at Newcastle to understand animal welfare and improve the lives of farm animals. As such, the results could help scientists and others figure out quality of life of pigs and possibly other farm animals in relation to their environment, the researchers say.

The next step is to refine and validate the technique to help scientists learn what's most important for a pig's well-being.

"Although techniques exist to measure stress, in the past we haven't been able to directly ask a pig if it is happy or not," Edwards said. "Instead we have assessed production systems based purely on human perceptions and our best interpretations of behavior."

The research, funded by Universities Federation for Animal Welfare (UFAW), was presented at the organization's annual conference in York last month.

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