The genetics behind behaviour

Wolves have been attacking cattle in North Thompson, an area north of Kamloops, B.C. Brenda Jones, who ranches in the area, reports maimed and dead cattle. Jones says that even uninjured animals are stressed, and calves aren’t gaining as much weight as they should. Her experience is all too common. There is no separating agriculture from nature, and predators are a part of nature.

Does domestication render animals more vulnerable to predators at a genetic level?  And can producers select animals that defend themselves against predators, yet allow themselves to be easily handled by humans? A paper written by Temple Grandin and Mark J. Deesing provides some insight into these questions.

Experience influences animal behaviour, though genetics plays a role as well. Herding behaviour, which helps protect herbivores from predators, is one example of this complex interaction.  If you’ve ever seen cattle bunch together, then simultaneously turn and chase a coyote or dog, you’ve seen why this social behaviour is such an advantage. Cows have even fought off bears by working as a team. Wayne Ray, a rancher in B.C., snapped the photo below. His cattle trampled a black bear that threatened a calf. The bear escaped, but the cows clearly won that battle.



Sheep stick even closer together than cattle. Sheep, of course, are much more vulnerable than cattle, and their strong flocking behaviour is one of their few defences against predators.

An animal’s flight zone is also affected by both genetics and experience. There is little doubt that low-stress methods make livestock easier to handle. However, within the same herd, there will often be a few animals with larger flight zones, even if their experiences are the same.

Flighty animals are generally more curious than their sedate herd mates. For example, a 1991 study found that easily startled pigs were also more likely to investigate a new object in their stalls. Other studies found that reactive pigs also investigated new environments more thoroughly and seemed to learn more quickly. A study done in 1980 found that cattle breeds with the largest flight zones were also more likely to approach strange objects. However, if driven towards a strange object, the flighty animals were more likely to spook. These studies seem to suggest a genetic link, and other research has shown that temperament is heritable.

While flightiness helps animals defend themselves against predators, extremely nervous animals are obviously difficult to handle. Grandin and Deesing have seen heifers that panicked and maimed themselves when their hooves jammed in a crack between a ramp and loading dock at a slaughter plant. Anyone who has worked with cattle can think of animals like this. Such cows need to be handled very careful so they don’t stampede or rush through a fence.

Fortunately, different aspects of temperament are influenced by different genes. Researchers proved that flocking behaviour and fear in birds are genetically separate. Tom Lasater, an American rancher, managed to select cows that defended themselves and their calves from predators, yet were tame. Heifers that couldn’t protect their calves and calve unassisted on the range were culled. Weaned calves that didn’t start eating from a person’s hand after two days were culled. The Lasater’s Beefmaster herd has been closed genetically since 1937.

All this suggests that producers can (and probably do) select for specific traits related to temperament, such as strong herding behaviour, while culling the fearful animals. But it's hard to know exactly what's going on at the genetic level. Perhaps someday producers will have enough genomic information to more easily pick animals that can keep predators at bay, while remaining calm around humans.

Grandin and Deesing's paper goes into more detail than I can cover in one blog post. They also talk about handling methods and systems. All the references to other research were drawn from this paper.