Potassium appears to influence biohydrogenation in the rumen, which, in turn, affects milkfat synthesis.
This is especially important, considering some of the trends we are seeing in our industry. For one thing, milkfat levels have hit some of the lowest levels seen in nearly two decades, according to data from AgSource CRI in Wisconsin and others. That can wreak havoc on milk checks. Milk prices have already taken a hit in recent years without the added problem of milkfat depression. Research presented at this summer's American Dairy Science Association annual meeting shows that potassium carbonate supplementation in the diet can help alleviate this problem.
According to the papers, increased potassium in the diet affects the fermentation and biohydrogenation pathways used by rumen microbes to convert unsaturated fatty acids to saturated forms. In experiments, an end-product of the biohydrogenation process — stearic acid — increased with increasing levels of potassium carbonate supplementation. Meanwhile, two fatty acids associated with milkfat depression — trans 10 C18:1 and trans 10 cis 12 CLA — decreased with potassium supplementation. And, the acetate-to-propionate ratio was higher with added potassium, and higher ratios tend to be associated with higher milkfat.
These events — and others — indicate that potassium impacts ruminal biohydrogenation and milkfat synthesis, points out Elliot Block, senior manager of technology at Arm & Hammer Animal Nutrition, who co-authored the papers along with Tom Jenkins, of Clemson University, and Joe Harrison, of Washington State University.
In previous experiments, reported at the ADSA meetings two years ago, Harrison and his group at Washington State found that cows fed diets with a higher dietary cation-anion difference (42 mEq/100 g vs. 25 mEq/100 g) produced an additional 3.3 pounds of milk (or 8.58 pounds of 3.5 percent fat-corrected milk) per day. And, he also found the higher-DCAD diets improved milkfat yield from 3.96 percent to 4.31 percent. The only difference between the diets was the inclusion of potassium carbonate.