Summary
Some boars look perfectly healthy and even have good semen quality — but their litters tell a different story. Researchers wanted to find out how common hidden chromosomal abnormalities (errors in a pig's genetic blueprint) are in Canadian swine herds, and what they're costing producers. A team from the University of Guelph tested 732 young boars across several Canadian farms. They analyzed each boar's chromosomes in the lab to check for structural errors. Nearly 1 in 60 boars (1.64%) carried a chromosomal abnormality. Affected boars produced litters with 4–46% fewer total piglets born, and more stillbirths and mummified piglets compared to their herd average. Because Canada lacks routine chromosome screening, these defects are quietly spreading through herds undetected. Researchers estimate the annual cost to Canadian producers could reach $4.6 million in lost piglets. Routine chromosome testing of boars before they enter breeding programs — especially AI centres — could prevent these losses and protect herd productivity for generations.