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Hog heaven

Tuesday, 2 October 2018  
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VetScript Editor's pick - October 2018

Animal scientist Kirsty Chidgey’s obsession with pigs began at Massey University and included a period breeding rare types for sale and eating. Two years ago she completed a PhD study investigating the relative merits of farrowing crates versus farrowing pens. It’s highly topical – and, in its conclusion, potentially controversial. Jacqui Gibson reports.


Animal Scientist Kirsty Chidgey completed her PhD at Massey University in 2016 – two years on, its findings couldn’t be more relevant. Kirsty’s thesis compared the impacts of farrowing crates and pens used on commercial pig farms in New Zealand.

Kirsty’s study, the largest of its kind to be carried out on a commercial farm, had two goals. She wanted to see if either farrowing crates or farrowing pens (with limited crating) were the better option for New Zealand pig farmers and their livestock. And she wanted to better understand the impact of each system on sow and piglet behaviour and piglet survival. Three years, hundreds of sows and thousands of piglets later, she found in favour of farrowing crates. “They’re still the best option to reduce piglet crushing,” she says.

Kirsty, now a New Zealand Pork animal welfare scientist and advisor, says she found piglet survival was highest in farrowing crates, with around 93.9% of piglets surviving to the weaning age of four weeks. “Keep in mind that sows biologically favour mortality of the weakest in order to raise the strongest, fittest offspring. So when piglets are born, they have to compete to find the udder, latch on, get colostrum and avoid getting squashed.”

In farrowing pens, which give sows more room than crates and can be designed to include some temporary crating, the piglet survival rate dropped by about four percent to 89.8%. However, in pens, piglets tended to experience more physical contact and vocalising from sows, which in turn resulted in similar mothering behaviour in the next generation of sows.
In Kirsty’s study, each farrowing pen was modified so that the sows had six days of temporary crating, initiated three days prior to farrowing.

From a piglet welfare perspective, says Kirsty, both farrowing crates and pens rate better than either outdoor farms, using farrowing huts, or nests made by sows in the wild. On outdoor farms, for example, farmers typically experience an 18% mortality rate, compared with a 12% mortality rate for indoor farms using farrowing crates. In the wild, piglet mortality rates can fluctuate between 25% to 60% due to factors such as weather, predation, disease and being squashed by their mothers.

“We know from my research and research done internationally that it’s a trade-off between the needs of the sow and piglet survival. Sows want to behave normally and build nests. Piglets need plenty of care to survive. Globally, we haven’t yet found a system that works well for both.”

Kirsty says New Zealand’s 100 commercial pig farmers are all too aware of the trade-off between sow welfare and behaviour and piglet survival. “I visited a lot of farms during my postgraduate studies and found farmers genuinely concerned about animal welfare and aware of the public sentiment against farrowing crates.”

In March this year, animal advocacy group SAFE presented a petition to Parliament signed by more than 100,000 people, demanding a ban on the use of farrowing crates. “I’d like to think my studies help people keep a balanced view of the issues and see that there’s a piglet welfare issue we need to address, too. By vetoing all use of farrowing crates, we do put piglets in a worse situation.”

Kirsty, 33, hasn’t always been an advocate for pigs. “I developed my obsession with pigs studying animal science at Massey. About halfway through my first year I moved to a four-hectare lifestyle block with my then boyfriend and now-husband, Nick. He was from a South Waikato dairy farm. I was a city kid from Wellington.”

Together they raised bobby calves, sheep and Kunekune pigs, and later bred rare European wild boar and Hampshire pigs for sale and eating. “I loved it. Everything I was learning at uni I could put into practice on the farm. That’s when my fascination with pigs started. They’re far and away my favourite animal – and I say that with my dog at my feet.”

It’s the intelligence of pigs that appeals to Kirsty, whose LinkedIn photo aptly features her face snuggled into a healthy piglet. “They make associations quickly. They learn how to respond to and interact with people. You get to know their personalities, and they learn to know yours. People often ask me, ‘Why pigs?’ There are so many negative connotations with pigs – ‘eat like a pig’, ‘live in a pigsty’ – but they are so far from the truth. Saying that, I am cautious around them. You have to know how to act around pigs to enjoy positive interactions with them. The first thing they’ll do when you walk into a pen is investigate you with their snouts, maybe bite you. But that’s how they explore – they use oral, nasal, facial behaviour.”

Today, Kirsty and Nick live on a 1.6-hectare lifestyle block near Palmerston North with sheep, cattle and chooks, which they raise mostly for their own source of meat. Pigs, she says, are a thing of the past.

“When I started the research for my master’s I could no longer raise or own any pigs because of the biosecurity issues associated with visiting commercial farms. The upside is that I still have a lot to do with pigs at work.”

Based at the School of Agriculture and Environment at Massey, Kirsty continues to research pig farrowing solutions on behalf of New Zealand Pork, ultimately looking for a system that works well for sows, piglets and farmers. Like the National Animal Welfare Advisory Committee (NAWAC), which approved the use of farrowing crates following a thorough review in 2016, she’s hopeful that a breakthrough may come from New Zealand farmers.

In a statement, NAWAC said there was no practical alternative system available yet that improved sow welfare while producing the same level of piglet survival as a farrowing crate. The committee encouraged the industry to look for innovative solutions and work towards alternatives.

“New Zealand farmers are innovative,” says Kirsty. “As a country, New Zealand was quick to phase out gestation or sow stalls. Half of our farming is outdoor based, which is really unusual by international standards. We’re strong on animal welfare policy and practice and we’re generating new knowledge and science all the time.”

She says the answer may lie in a new kind of combined farrowing pen and crate model, or something else altogether. For now, she and New Zealand Pork are keen to know more about how the country’s hobby farmers are breeding and caring for their pigs, and she hopes veterinarians can help. “We don’t know much about this group. We don’t know how they farm, or even how many lifestyle pig farmers there are. Ministry for Primary Industries’ figures suggest there could be between 2,000 and 8,000 properties with pigs, so that’s potentially a big group to learn from.

“I’d love to hear more from mixed practice veterinarians. What kind of health and welfare issues are they seeing? How could an organisation like New Zealand Pork help hobby farmers? What do your pig clients want? How could we work more closely together to share information? I think we need closer collaboration to come up with new and better solutions.

To me, veterinarians are an important part of the conversation, and I’d love to talk more with them.”