Limiting abnormal chromosomes can mean more piglets per litter

University of Guelph-developed test identifies boars with abnormal chromosomes that affect fertility

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Technology developed at the University of Guelph can help increase the number of piglets born by an average of three to four per litter.

That’s due to Karyotekk, a Guelph start-up that can identify chromosomal abnormalities in boars that affect their fertility, resulting in fewer piglets per litter. The business is based on research by Dr. W. Allan King, professor in the Department of Biomedical Sciences and Canada Research Chair in animal reproductive biology.

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Why it matters: Genetic abnormalities in boars can be passed on to their offspring and affected animals show no outward sign of problems, which can affect reproductive efficiency.

Chromosomes are the structures that hold the genes and they must be copied exactly and passed on to offspring. If they don’t, it can result in problems producing sperm or eggs.

“This happens spontaneously and when it passes from parent to offspring, it can become fixed in the herd,” King says.

“The effect is on litter size, about four piglets less per litter and that can be pretty significant,” he added. “We discovered that about one in 200 occurs from normal parents and if they’re not removed, they pass it to their offspring, and we also discovered if you start to eliminate the (affected) boars, the frequency goes down.”

Allan King, Diana Carvajal, Tim Carter and Stacey Del Castillo in a lab at the University of Guelph.
photo: Lilian Schaer

The abnormalities are naturally occurring and not breed-specific. King has some work underway to look at causes behind them, but because they generally happen spontaneously, it’s not a problem that can easily be fixed through gene editing, for example.

According to King, Karyotekk provides swine breeders in particular with the opportunity to have their boars tested before they go into service. A blood sample is all that’s needed to run the test, which has a turnaround time of about two weeks.

An economic assessment conducted by AgriFood Economic Systems of Guelph last year shows the testing can pay off.

The benefit cost ratio of investing in the screening test is over 5:1 – for every dollar spent on testing, revenue increases by $5.30. And under the model assumptions, the net expected benefit per boar was estimated at $747.

Lead researcher Dr. Claudia Schmidt, now an assistant professor at Penn State University, notes that the actual financial benefit of the test can vary greatly due to a variety of production factors, but overall, the higher the gross margin per hog, the higher the return on investment for testing the boars.

“Hogs have the highest rate of chromosome abnormalities among domestic animals. Testing boars before breeding and eliminating carriers can reduce the incidence in the herd,” she says.

It is estimated that the problem affects one to two per cent of boars, but can quickly become compounded when those animals come into reproductive service. Because the impact is fewer piglets born per litter, the problem is often a hidden cost for producers. Pooled semen use is also quite common, which can further mask the issue in a herd.

That means the test is a positive development for the industry, but according to Brian Sullivan of the Canadian Centre for Swine Improvement, the biggest challenge to widespread adoption currently is the $175 price tag per test.

“The challenge is that you have to screen 100 boars to find the one; it’s an expensive screening process for genetics companies and the commercial industry isn’t necessarily prepared to pay that cost,” he says.

An added challenge is that these are abnormalities that occur naturally at a low frequency, so screening a herd isn’t a one-time activity, he added, but it is a process that works well to prevent transmission to progeny.

Automation will help bring the price down, and a grant from ag accelerator Bioenterprise has helped Karyotekk test the efficiency of using more automated microscopy. Funding from the Gryphon’s LAAIR program funded the economic impact assessment.

“It’s an investment to get into this, microscopes are expensive, but I think it’s (the technology) important to producers and to users,” says King.

Karyotekk is currently the only provider of this service in Canada.

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