Dr. Joseph Harrision
, professor and researcher at Washington State University.
Dr. Joseph Harrison, professor and researcher at Washington State University, is involved with extensive research related to dairy cattle nutrition and its influence on nutrient management. The following research focuses on the effects of potassium and positive dietary cation-anion difference (DCAD) levels on lactating dairy cattle performance.
Tell us a little about your experience with DCAD research.¹
Potassium is an essential regulator of sweat glands, helping keep cows cool, maintain rumen integrity and produce high levels of milk. Realizing that dairy cattle lose excessive amounts of potassium each day through normal daily functions and production needs, our research has focused on increasing levels and delivering potassium to the dairy cow.
In our study, 30 Holstein cows were randomly assigned to one of two groups at 15 days in milk (DIM) through 85 DIM. The Control group was fed potassium through forage sources only at the rate of 1.2% dry matter, resulting in a ration formulated for a DCAD of +25 meq/100g ration dry matter. Treatment cows were supplemented with DCAD Plus® Feed Grade Potassium Carbonate to increase dietary potassium to 2% dry matter and to increase DCAD to +42 meq/100g as shown in the table below.
What were the results of boosting DCAD in lactating cow rations?
Through our research we found that boosting DCAD levels in the early stages of lactation can optimize dry matter intake (DMI) and increase milk and component yields. The chart below outlines the significant improvements in milk fat that were seen in cows fed DCAD Plus. We attributed these improvements to additional rumen buffering to help stabilize the high metabolic acid load occurring to meet the production demands of early lactation animals.
From the trials and milk samples we discovered that potassium also has an effect at the rumen level, lowering the amount of trans-fatty acids in fluid milk.
What are the implications of these findings for dairy producers?
Over the last 18 months, dairy producers have faced many financial hardships; increasing the DCAD levels in the early lactation cows of your herd can improve income over feed cost (IOFC) through increased component levels and feed efficiency.
1 White R, Harrison J, Kincaid R, Block E, St-Pierre N. Effectiveness of potassium carbonate to increase dietary cation-anion difference in early lactation cows. J Dairy Sci 2008; 91: Abstr. 106