Beginning in December 2025, Brown Swiss, Canadienne, Guernsey, and Milking Shorthorn producers will have access to genetic evaluations for Subclinical Ketosis (SCK)—a major step forward for herd health and breed improvement.
Until now, Lactanet’s Metabolic Disease Resistance (MDR) evaluations were only available for Holstein, Ayrshire, and Jersey cattle. Years of accumulating milk BHB data from smaller population breeds has now made expansion possible.
Why Subclinical Ketosis Matters
Subclinical ketosis occurs when cows experience a negative energy balance in early lactation, causing ketone levels in the blood to rise. Unlike clinical ketosis, SCK is often silent, yet it can lead to:
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Lower milk production
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Reduced fertility
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Impaired immune function
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Higher risk of other metabolic diseases
Because the condition is easy to miss without testing, many herds rely on milk beta-hydroxybutyrate (BHB) monitoring, such as Lactanet’s KETOLAB program, to identify at-risk animals.
Data Behind the New Evaluations
Lactanet’s milk recording system analyzes milk BHB on every test day, which has steadily built a large enough dataset to support genetic evaluations for additional breeds.
Current BHB record counts include:
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Brown Swiss: ~7,000 first-lactation records; >13,000 later-lactation
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Canadienne, Guernsey & Milking Shorthorn: ~1,300 first-lactation; ~3,000 later-lactation each
However, data for clinical ketosis and displaced abomasum remains too limited for reliable evaluations in these breeds—so for now, Subclinical Ketosis will be the sole component of their MDR index.
Metabolic Disease Resistance Index for Smaller Breeds
Holstein, Ayrshire, and Jersey cattle currently receive an MDR index based on three traits:
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Subclinical Ketosis — 50%
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Clinical Ketosis — 25%
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Displaced Abomasum — 25%
For the four smaller breeds, the MDR index will instead be 100% Subclinical Ketosis, combining results from both first and later lactations.
The index will use the familiar Relative Breeding Value (RBV) scale, with:
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Average: 100
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Standard deviation: 5
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Higher RBV = greater genetic resistance to SCK
Number of official sires now evaluated:
| Breed | Official Sires |
|---|---|
| Brown Swiss | 122 |
| Canadienne | 27 |
| Guernsey | 30 |
| Milking Shorthorn | 24 |
Producers will find the new MDR results on LactanetGen.ca within each animal’s Genetic Evaluation Summary under the Functional Traits section.
Why This Matters for Herd Health
Metabolic disease is one of the most costly challenges in early lactation. With MDR evaluations now available for every dairy breed in Canada, breeders can combine:
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Better genetic selection
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Strong transition cow management
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Early-lactation monitoring
This combined approach offers the most effective pathway to reducing metabolic disease risk and improving long-term herd performance.
