New research on transition cows shows that dairy farmers should adjust traditional ways to manage post-calving calcium levels and ketosis.
More than half of dairy cows in high managed herds go through the transition period to milking with at least one health problem. Recent research shows those problems lower the cow’s chance of success throughout the rest of her lactation.
Why it matters: Researchers are discovering ways to better manage hypocalcemia, also called milk fever.
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Dr. Stephen LeBlanc of the University of Guelph says that number isn’t surprising. About 50 per cent of NHL hockey players will have an injury for which they’ll miss at least one game. Similarly, dairy cows are considered athletes for the precision with which they produce large volumes of milk.
LeBlanc says numerous studies have shown the effect of transition period illnesses on reproduction.
A Florida study with a dataset of 4,000 cows showed that if a cow was sick during transition and got pregnant, that wasn’t the end of worry for the farmer.
“Even the cows who got pregnant, if they had lived through one disease, or even worse, two diseases two, three, four, five months in the past, they were much more likely to lose that pregnancy subsequently,” LeBlanc said during the Progressive Dairy Operators triennial symposium in Toronto.
Managing transition illness is key.
LeBlanc says there’s new thinking on use of calcium to avoid milk fever, and he recommends monitoring cows for ketosis and body condition score to understand cows’ metabolic challenges.
[AUDIO] Listen to Dr. Stephen LeBlanc explain what new thinking on hypocalcemia means for on-farm management.
Better transition cow nutrition leads to many fewer cases of clinical hypocalcemia, also known as milk fever. However, that also requires more attention paid to the process of managing calcium in cows post-calving.
Researchers have found that a drop in blood calcium the day after calving is normal, as long as the cow’s blood calcium quickly recovers on the second day.
“Now we’re measuring cows at day four after calving, not on day one.”
Cows in a Cornell University study in New York led much of this new thinking. Those that didn’t recover their calcium by day four post-calving had worse outcomes.
“Cows that were discalcemic didn’t recover well and had the worst reproductive performance two or three months into the future,” says LeBlanc.
The cows didn’t have low calcium at breeding or when they were preg checked, but because they had low calcium shortly after calving, their future reproductive ability was affected.
Researchers are trying to figure out how to manage cows when blood calcium doesn’t recover after day four.
They are also questioning whether the current practice of providing calcium treatments, usually through a bolus after calving, has much effect.
“These can have a niche. There’s a place for them,” says LeBlanc. “But we need to be honest with ourselves. That’s not going to just fix the problem because we gave a drench or a bolus.”
Keeping tabs on ketosis
Ketosis is a metabolic disease of ruminants. When cows produce excess amounts of ketones in their blood, it has numerous impacts, including greater risk of metritis and subclinical endometritis. This uterine inflammation creates 50 per cent less chance that the cow will cycle.
This happens around the transition period, but LeBlanc says chances are small that a cow is still ketotic when bred, so ketosis at that point also has long-term effects.
As with low calcium treatment, there are changing thoughts on how to treat ketosis. At one point dexamethasone was used to manage it, but that’s no longer recommended.
Research has shown that once-per-day milking can help eliminate ketosis, but that will also reduce the cow’s yearly production.
Research has also shown that drenching ketotic cows with propylene glycol can help, but 25 per cent of them still have elevated ketone levels after treatment.
Monitoring recommendations
LeBlanc recommends attention to transition cow challenges in a herd.
- Measure the betahydroxybutyrate (BHB) levels of fresh cows. BHB is an indicator of high ketone levels. Sample the next 30 cows that calve three times between three and 12 days in milk, either with milk or blood tests. If more than 15 per cent have higher ketone levels, find out why.
- Monitor cows for puss discharge once between 15 and 42 days in milk. If more than 15 per cent are identified, that’s a concern. If the frequency is greater than five per cent and first insemination pregnancies are less than 40 per cent, find the cause and treat.
- Check body condition score at calving and at four weeks post calving.
- Review metritis detection and treatment. Cows with a fetid discharge at less than eight days in milk will likely benefit from treatment.
