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Potassium source matters

Elliot Block Published on 09 February 2012

Potassium is a nutrient critical for the health and performance of lactating dairy cows. Large amounts of potassium are lost through milk production, so cows need supplemental potassium just to meet daily maintenance requirements.

Potassium is also in high concentration in sweat, requiring even higher dietary levels during heat stress conditions to mitigate losses from sweating, panting and urination. And newer research shows potassium may help reverse the negative effects of milk fat depression.

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Bottom line: Cows need potassium and lots of it. But new research shows that the source of the potassium matters too, and feeding the right source can make a difference in performance.

Initial research links potassium and milk fat

Research conducted in 2010 at Washington State University found that when cows were fed a commercial stabilized potassium carbonate source, milk fat production increased significantly.

Following this on-farm study, a fermenter trial at Clemson University investigated the mechanisms by which potassium carbonate influenced fat production.

The trial concluded higher levels of potassium led to more complete biohydrogenation of trans fatty acids (conjugated linoleic acids) in the rumen. More complete biohydrogenation means less trans fatty acids and more milk fat production.

“Our 2010 research found that potassium carbonate caused rumen activity to return to a normal state with much reduced levels of undesirable trans fatty acids that cause milk fat depression,” says Dr. Tom Jenkins, professor in the Department of Animal and Veterinary Sciences at Clemson University.

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“These results spurred additional research to determine whether different potassium sources could produce the same effect.”

Benefits with the right potassium source

New research by Jenkins took his initial research findings to the next level and investigated the effect, if any, different potassium sources would have on biohydrogenation.

The study provided a closer look at the effect of potassium carbonate, potassium chloride and no supplemental potassium (control) on the production of intermediate trans fatty acids associated with milk fat production or depression.

The study evaluated six diets using rumen fermenters:

  • High-fat diets (supplemented with soybean oil):
  1. No added potassium
  2. 3 percent potassium from potassium carbonate
  3. 3 percent potassium from potassium chloride
  • Low-fat diets:
  1. No added potassium
  2. 3 percent potassium from potassium carbonate
  3. 3 percent potassium from potassium chloride

The study closely examined how different potassium sources impacted the pathway by which biohydrogenation in the rumen takes place.

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Two pathways exist – one desired pathway and an abnormal pathway which can cause milk fat depression.

Table 1 outlines which intermediate trans fats result in more ideal biohydrogenation through the desirable pathway and which can cause the abnormal pathway, and potentially milk fat depression, to occur.

Potassium carbonate outperformed potassium chloride and the control, delivering the following benefits:

  • 0312pd block fg 1 full

    More complete biohydrogenation: Potassium from potassium carbonate caused a more complete biohydrogenation of rumen fatty acids through the more desirable pathway to produce stearic acid (C18:0) and palmitic acid (C16:0).

As Figures 1 and 2 show, this same effect was seen in both high-fat and low-fat diets.

Greater biohydrogenation means more saturated fatty acids are created, which can be used for milk fat production.

  • 0312pd block fg 2 full

    Improved production of desirable intermediates: Rations containing potassium carbonate improved the intermediates associated with the desirable pathway of rumen fatty acid biohydrogenation crucial to reaching peak milk fat production. See Figures 3 and 4.

  • Increased acetate and butyrate, the volatile fatty acids (VFAs) responsible for half the fat destined for the udder: More VFAs translate to additional milk fat in the bulk tank and the milk check.

0312pd block fg 3 full

Research conclusions

The benefits associated with increasing dietary potassium with potassium carbonate were not observed when potassium chloride was used as the source of dietary potassium.

Researchers concluded that chloride must have negated the positive effects associated with potassium in the rumen.

Utilizing these research conclusions, Jenkins is hopeful that stabilized potassium carbonate can serve as a remedy for dairy operations

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experiencing low milk fat levels.

Potassium carbonate can help dairy producers improve profits by boosting milk fat production.

“Although we know the benefits potassium carbonate offers to the dairy herd, there is still more to understand about its mechanisms,” Jenkins says.

“Research at Clemson continues to further evaluate how potassium carbonate works at improving conditions in the rumen.” PD

References omitted due to space but are available upon request to

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