Genes May Hold the Key to Hog Heaven
Forget any ideas you might have that hogs are gentle, sociable creatures like Porky Pig or Arnold, the cherubic charmer from TV’s “Green Acres.”
Many have a mean streak that researchers say is costing hog farmers billions of dollars a year.
The aggressive nature of hogs “is having an immense impact on commercial production,” said Bill Muir, a Purdue University genetics professor.
Muir and other researchers believe that the pigs’ genes hold the answer to tail biting, food hoarding and fits of bullying, that simple heredity makes some hogs more aggressive, others more submissive.
If you crowd pigs into a pen, the dominant one will hog--so to speak--the food and often fight with the “lesser” pigs.
But the aggressive hogs that eat more than their share don’t gain anything from the excess, while those that don’t eat enough don’t grow as fast. And all the hogs are stressed by trying to maintain their dominance or avoiding being bullied.
Farmers have to use more feed than is actually necessary to make sure every hog eats.
“It’s not only taking longer for the hogs to grow, it’s taking more food to get there,” Muir said. “So you’ve got this double whammy that’s hitting hog producers.”
That costs the industry, which produces about 100 million hogs a year, about $5.6 billion annually.
Commercial hogs, kept eight or more to a pen, grow at an average rate of 1.6 pounds per day, Purdue animal scientist and geneticist Allan P. Schinckel said.
If only two or three pigs are kept in a pen, there’s less crowding and aggression and the hogs grow at a rate of 2.3 pounds per day.
“A good part of the swine industry realizes that if we raise these pigs under ideal conditions, we make the pigs fly in terms of performance,” Schinckel said.
But this is not an ideal world.
Muir and Schinckel believe the answer lies in the expanding field of genomics. “The gene solves the problem. We just have to find out which one it is,” Muir said.
If the responsible gene, or genes, can be located, a simple blood test could be used to identify the most aggressive hogs. Then, using selective breeding or genetic engineering, a line of docile hogs could be developed that could be raised without fighting, overeating and stress.
Muir’s laboratory so far has focused mainly on chickens.
With vicious fights and even cannibalism being common among confined chickens, farmers trim the birds’ beaks to limit the harm they can cause each other. And as with hogs, confined chickens can suffer extreme stress, which can slow their growth and make them more susceptible to disease.
