When temperatures climb and humidity settles in, dairy producers their nutritionists spend plenty of time thinking about heat stress. But warm, damp weather can also create problems before the feed reaches the bunk.
During the The Dairy Nutrition Blackbelt Podcast, Dwain Bunting from Barentz Animal Nutrition North America explained how summer conditions can increase the reactivity of potassium carbonate and other mineral buffers. The result can be excess heat in mineral mixes, increasing the risk of caking, clumping and unwanted chemical reactions during storage and handling.
Summer Drives Potassium Demand
As cows experience heat stress, many nutritionists raise potassium levels to support feed intake and production. That often means relying on potassium carbonate because it contributes potassium while adding buffering capacity and increasing dietary cation-anion difference (DCAD).
Bunting says adding potassium isn’t always an easy decision because every increase raises ration costs. Still, stronger milk prices have encouraged many nutritionists to include more potassium during the summer.
“Milk prices are a little better, so we’re more committed to add that extra potassium,” Bunting says.
Potassium carbonate has become a common choice because it delivers more than potassium alone.
“We would prefer to be able to use a source of potassium that also brings along a little buffering capacity or a little bit of positive DCAD,” he says.
Heat and Humidity Raise the Stakes
Many summer rations also contain sodium bicarbonate or sodium sesquicarbonate to increase buffering capacity. While those ingredients can benefit the ration, Bunting says they also increase the chance of unwanted reactions when combined with heat and humidity.
“We certainly have to be more cautious about that,” he says.
Dense mineral premixes with high concentrations of reactive ingredients can build heat, especially when moisture enters the mix. That’s why Bunting encourages nutritionists to work closely with feed manufacturers during formulation.
He believes mills shouldn’t hesitate to question formulations that appear overly concentrated.
“They should really double back and go, ‘This is kind of a high level of potassium carbonate. Maybe you should back off a little, or would you give us permission to dilute this out a little bit more?’” Bunting explains.
Those conversations may help prevent problems before ingredients reach the mixer.
Not All Potassium Carbonate Reacts the Same
Bunting says nutritionists have several options if they’re concerned about mineral stability during humid weather. Traditional feed-grade potassium carbonate remains widely used, but particle size can make a difference.
“If you get something that’s a little bit more granular, you might pay a little bit more for that, but that can give you a little bit less reactivity,” he says.
Another option is potassium carbonate sesquihydrate, which Bunting says generally performs well under humid conditions. He says some potassium carbonate products are also manufactured with a thin layer of fat to reduce their reactivity.
“We actually embed a little bit of fat,” Bunting explains. “It lowers the reactivity, and it also makes it more granular.”
Dust Can Create Hidden Problems
Beyond ingredient selection, Bunting encourages nutritionists to pay attention to the physical characteristics of mineral mixes.
Dusty ingredients have more surface area, allowing them to absorb moisture more readily. As humidity rises, those fine particles can increase the chance of heat generation.
“If you’re feeding something that’s really dusty, talk with your nutritionist about it,” Bunting says. “Dusty ingredients deserve a closer look.”
He adds that moisture and heat become the biggest concerns when manufacturing dairy protein or mineral mixes.
“The more moisture that is in there, the more likely it is we’ll have a problem,” he explains.
That makes summer a good time to evaluate whether mineral blends are overly fine, whether storage conditions expose feed to warm, humid air, and whether highly reactive ingredients are being combined at high inclusion rates.
Low Inclusion Rates Still Create Heat
One of Bunting’s biggest cautions is that heat generation isn’t limited to high levels of potassium carbonate.
Research conducted by Barentz has shown that even relatively low inclusion rates can produce considerable heat under humid conditions.
“There’s really not a safe level,” Bunting says. “You can be at a really, really low level and it’ll still produce a lot of proportional heat.”
His advice is straightforward.
“When it’s hot like it is, just pay more attention,” he says. “The potential for these reactions is always there.”
What Nutritionists and Feed Mills Should Watch
Bunting’s recommendations for summer formulation include:
- Review potassium inclusion rates as summer rations change.
- Work with feed mills to avoid overly dense or highly reactive premixes.
- Consider more stable potassium sources, including granular or coated products.
- Minimize dust whenever possible to reduce moisture uptake.
- Remember that mineral mixes may behave differently during hot, humid weather than they do in winter.
A ration can look right on paper, but Bunting says summer heat and humidity can change how those ingredients behave once they hit the mixer. Paying attention to storage, mixing and ingredient selection can help prevent problems before feed ever reaches the bunk.
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