When Animals get Aggressive

Managing harmful behaviour that can occur in swine production.

by Colleen Halpenny

While aggression is a natural trait in any animal, in swine it can be extremely detrimental, with after-effects like physical damage or changes in an attacked animal’s behaviour.

Animals exhibit aggression to establish dominance within a new group setting, or lay claim to a highly sought-after resource, such as feed or water. However, producers, researchers and production chains are working to find new ways to limit these outbursts before they negatively impact animal health and overall productivity.

Take time to observe

Dr. Isaac Huerta, technical services manager of Western and Southern Europe and Africa with PIC, comments that “producers know pigs, but having enough time to observe each new group and understand their behaviour is limiting. You cannot constantly be in the room with them.

pig playing with chain toy
    Martin Schwalbe photo

“Some small adjustments to their environment, whether that be the air quality or temperature, can have positive impacts on their social behaviour and you can get ahead of some of these issues before they escalate,” he says.

Nat Stas, PIC technical services manager for Eastern U.S. says a lot can be learned through observation.

“Sometimes we can be so focused on the next step. If we just took the time to stand in the room, we could learn a lot about what this group is experiencing and how they are interacting with their social group.”

As part of your daily routine, make the time to stand in each room to observe all pigs, note feeding and drinking patterns, how social they are, and any clustering.

PIC recommends one labour hour per 500 nursery-aged pigs, especially during the first 10 to 14 days, and one labour hour per 1,000 pigs at the finishing stage.

The inclusion of barn monitoring cameras has drastically increased in recent years. Richard Switzer of Precision Cam based in Brandon, Man., says, “if you can save one animal, the system pays for itself.

“The ability to stay in constant contact while you complete field work, enjoy family time, or leave the property; these systems provide a great peace of mind to farmers,” he says.

Noting that systems are calibrated to handle the extreme Canadian winters and that “video quality is so crisp and clear, farmers are able to pan around and see the whole picture. That added level of confidence to view your livestock when you aren’t there makes a world of difference.”

With the ability to have multiple users viewing from the house, laptops, or cell phones, your entire operation is linked to monitoring your investments.

“Previously we were installing these systems mainly into cattle operations but they’ve quickly been taken up by those in the pork, sheep, horse and goat industries,” comments Switzer.

Genetics at work

Animals in a production system, while removed from their wild environments, still exhibit those natural instincts.

How those instincts are interpreted, however, is varied. Making management adjustments to allow for the pigs to positively interact in their preferred settings takes time and a willingness to learn.

“We can’t rely on what we’ve always done,” Huerta advises. “The needs of pigs are constantly evolving, so we need to evolve our management practices to adapt to their new needs and prevent stress.”

Dr. Justin Holl, a geneticist at PIC, notes that some behaviours are resultant from the pigs’ environment and new interactions. “We have complex elements at play making momentary decisions; how do we help producers understand what is truly typical behaviour?”

He notes that when you have multiple genetic lines on your farm, it’s an interesting question to ask which is your most, or least favourite, and why.

pig looking into camera
    Mark Stebnicki photo

“The most common response from farm owners or staff comes back to behaviour. One may be friendlier, or more curious, or prone to be flighty compared to others. The producers and staff work with the pigs day in and out and can give you best insight on how the management of these pigs can be best optimized.”

In terms of year-over-year genetic improvement, he says, we want to be consistent.

“We’ve seen this over the last few years with things like growth rates, which may mean we have an animal who may need to eat more, and we would need to adapt for their dietary needs. How do we deliver the right amount of feed, nutrients, and balance to these animals?”

One of the most exciting areas of research focuses on how selection for behaviour traits can be optimized.

Holl says, “a lot of research is being done for positive behaviour – they call it a social genetic effect. So not only is this pig entering a pen affecting their own ability to eat but how will they affect the others. Is he encouraging others to come eat with him, or protecting his neighbour from being bothered by others? We’re looking into whether these are heritable traits and to try and better understand. The goal is for it to make larger positive impacts for breeders.”

Impacts of aggression

In a November 2021 study published in Applied Animal Behaviour Science, Lucy Oldham and fellow researchers from Scotland’s Rural College identified that future behaviours of subsequent aggressive and non-aggressive pigs are determined from the outcome of a single fight.

It was found that those pigs who have had positive outcomes from an aggressive interaction were more likely to engage in a confident manner in future encounters. Whereas those who were deemed the loser in previous fights were observed to appear timid and seek escape routes to remove themselves from the situation.

Stas observes that “from a commercial end if we can identify the biter, we would like to remove them from the others. If we have space in another pen or corner with feed and water access, let’s set them aside while still being able to get them to market.

“But it’s not uncommon that the aggressive pig is usually one of the smaller pigs. It’s interesting to watch and wonder, are they limited on resources or getting pushed out by the larger pigs?”

He suggests when observing non-positive behaviours, first review overall management practices. “Something is creating disharmony in that pig’s life.”

Huerta advises “it’s not just about water and air quality, it’s also about quantity and how easily accessible these are to all pigs in your group. Anything that changes the surroundings of the pig, even having an empty feeder for a few minutes – these can be stressors which make the pig feel uncomfortable.”

They both note changes to behaviour are usually always multifactored, the root is not a single challenge.

Enrichment opportunities

Enrichment opportunities in the forms of straw, chains, wood, ropes and rubber balls have widely been adopted by producers as a positive additive to the pig’s environment.

piglet playing with yellow spikey toy
    Ontario Pork photo

Under the PigCARE section of the Canadian Pork Excellence program, there is a requirement to include two or more enrichment options to pigs at all stages of production.

These strategies in addition to enhancing animal welfare and improving the physical and social environment for pigs, enrichment strategies, such as providing objects suitable for chewing and rooting, can deter pigs from harmful social behaviour such as ear and tail biting, thereby reducing the impact of these problems.

It can also reduce aggression when pigs are mixed in together and reduce handling stress.

piglets playing with black tubing
    Martin Schwalbe photo

PigCARE also reminds producers to keep enrichment toys in rotation to work with the pigs’ natural exploratory and curious nature.

Holl does caution to not “rely on enrichments to fix the problems. Still, look at your operation as a whole and utilize the toys as extras for positive behaviours.”

Huerta agrees. “Adding the enrichment is the beginning of the solution, but it goes beyond adding the straw and wood. This is one part and it’s important, but if the rest of your barn’s environment isn’t in line it won’t work. If the temperature of the room is wrong, feeder space or location of the drinkers isn’t ideal, you won’t see these benefits.”

Stas is always looking to the future on evolving management and handling practices. “I like to challenge producers on how far ahead they’re planning. How many pigs per sow per year are we aiming for? How do we work to make sure the flow supports that, with nursery or finish space, to accommodate those production goals? Is your growing barn set up to accommodate larger finishing weights, to still allow them to interact and have ideal feeding, water and ventilation set-ups?”

He comments on big picture observation. “We need to continue to observe and get below that intervention level before we face these challenges. A wean-to-finish manual comes out every four to five years and we work with producers, geneticists, academics and nutritionists to compile the information and update recommendations.”

The top goal remains “to find not only what is the most cost-effective way to raise a pig, but what’s the best way to do that to minimize the challenges producers face.”

Industry partners continue to work together with producers’ needs in mind with new research facilities and projects aimed at advancing animal care and production practices over time. BP

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