DNA strands forming a pig, symbolizing genetics and meat production.

Decoding Pig Genetics: How Epistasis Could Revolutionize Meat Production

Beau Callahan in Science & Nature August 2025 • 4 min read.

"Unlocking the secrets of gene interactions in pigs could lead to more efficient and sustainable meat production."

For years, scientists and breeders have been trying to understand how genetics influence the characteristics of livestock, especially when it comes to meat production. We've learned a lot about individual genes and their effects, but it turns out that genes don't work in isolation. They interact with each other in complex ways, a phenomenon known as epistasis, which can significantly impact traits like carcass composition in pigs.

Epistasis refers to the interaction between different genes, where one gene can mask or modify the effect of another. These interactions can be additive, where the combined effect is the sum of individual effects, or non-additive, where the combined effect is greater or less than the sum of individual effects. Understanding epistasis is crucial because it can help us predict how specific genetic combinations will influence desired traits.

A recent study published in the Journal of Animal Science sheds light on the role of epistasis in determining carcass characteristics in pigs. The researchers investigated how interactions between quantitative trait loci (QTLs), regions of DNA associated with particular traits, influence body composition. These findings are key to optimizing breeding strategies and enhancing meat quality and production efficiency. Let's break down what this research means for the future of pork production.

What Does This Study Tell Us About Epistasis in Pigs?

DNA strands forming a pig, symbolizing genetics and meat production.

The study focused on a population of pigs descended from Pietrain sires and crossbred dam lines. Researchers analyzed a large number of animals, tracking data on carcass cuts, lean tissue, and fat tissue weights. They looked at over 80 molecular markers spread across several chromosomes to identify significant epistatic QTL pairs—gene combinations that together influence specific traits.

Here’s a summary of the main points:

Prevalence of Additive Interactions: The most common type of gene interaction observed was additive × additive, meaning the combined effect of these genes was simply the sum of their individual effects.
Location of Epistatic QTL: Epistatic QTLs were found on almost all chromosomes studied, except for SSC13, indicating that gene interactions affecting carcass traits are widespread throughout the pig genome.
Percentage of Phenotypic Variance: Epistatic QTL pairs accounted for a notable portion (5.8% to 10.2%) of the phenotypic variance, highlighting that epistasis plays a significant role in determining these traits.
Specific Chromosomes of Interest: Chromosomes SSC1, SSC2, SSC4, SSC6, SSC8, and SSC9 harbored the greatest number of epistatic QTLs, making them key targets for further investigation.
Major Effect QTL Pair: The epistatic QTL pair with the greatest effect was identified for entire loin weight between two locations on SSC7, explaining 10.2% of the phenotypic variance. This discovery underscores the importance of specific gene combinations in optimizing valuable carcass traits.

These results emphasize that genetic interactions are crucial for the genomic regulation of body composition in pigs. By accounting for epistasis, breeders can better understand and manipulate complex traits.

What Does This Mean for Pig Farmers?

Understanding epistasis is more than just an academic exercise; it has practical implications for pig farming. By identifying key gene interactions, breeders can develop more effective breeding strategies to improve carcass quality. For example, knowing that specific combinations of genes on SSC7 have a major impact on loin weight could guide selection decisions, leading to animals with more desirable traits. The goal is to create pigs that produce high-quality meat more efficiently, improving both profitability and sustainability.

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Everything You Need To Know

What is epistasis and why is it important in pig breeding?

Epistasis is the interaction between different genes, where one gene can mask or modify the effect of another. Understanding epistasis is crucial in pig breeding because it helps predict how specific genetic combinations will influence desired traits like carcass composition. This understanding enables breeders to develop more effective strategies to enhance meat quality and production efficiency. While the text focuses on carcass characteristics, other traits influenced by epistasis, such as disease resistance or growth rate, are not discussed here but are important in pig breeding.

How does the study in the Journal of Animal Science contribute to our understanding of epistasis in pigs?

The study in the Journal of Animal Science identifies specific epistatic QTL pairs—gene combinations—that influence carcass characteristics in pigs. It highlights the prevalence of additive × additive interactions and pinpoints specific chromosomes (SSC1, SSC2, SSC4, SSC6, SSC8, and SSC9) harboring the greatest number of epistatic QTLs. The study also identifies a major effect QTL pair on SSC7 that significantly impacts loin weight. The results emphasize that genetic interactions are crucial for the genomic regulation of body composition in pigs. The study, however, doesn't detail the specific molecular mechanisms behind these interactions.

What are additive and non-additive interactions in the context of epistasis, and why does it matter for meat production?

In epistasis, additive interactions mean the combined effect of genes is the sum of their individual effects, while non-additive interactions mean the combined effect is greater or less than the sum of individual effects. Understanding whether gene interactions are additive or non-additive is critical for meat production because it allows breeders to predict how specific genetic combinations will influence carcass traits. Additive effects are simpler to predict, while non-additive effects require more complex analysis to optimize breeding strategies. This knowledge is essential for creating pigs that produce high-quality meat more efficiently. Other factors such as feed quality and environmental conditions also play a role, but aren't considered here.

What practical steps can pig farmers take based on the findings about epistatic QTLs on chromosomes SSC1, SSC2, SSC4, SSC6, SSC8, and SSC9?

Based on the findings about epistatic QTLs on chromosomes SSC1, SSC2, SSC4, SSC6, SSC8, and SSC9, pig farmers can focus their breeding strategies on these specific regions of the pig genome to improve carcass traits. By selecting for favorable gene combinations on these chromosomes, they can enhance meat quality and production efficiency. However, this requires genetic testing and analysis to identify animals with the desired gene combinations. Though the information provides key areas to investigate, it doesn't include the specific genetic markers or tools needed for implementation.

How can understanding the epistatic QTL pair on SSC7, which significantly impacts loin weight, revolutionize meat production?

The discovery of an epistatic QTL pair on SSC7 that greatly influences loin weight enables breeders to directly target this specific gene combination to optimize a valuable carcass trait. By selectively breeding pigs with this favorable gene combination, farmers can produce animals with larger loins, increasing the yield of high-value cuts and improving profitability. The ability to precisely manipulate this trait through genetic selection represents a significant advancement in meat production. This approach does not account for consumer preferences or market demands, which also play a significant role in determining the value of specific cuts.