Low milkfat issues continue to be a concern on many dairy farms throughout the U.S. This is a serious economic issue, says Adam Lock, nutritionist at the University of Vermont.

A small reduction in milkfat percent, depending on the milk-pricing system, can cause a significant drop in milk price per hundredweight. Milkfat depression is the result of several dietary factors, not just one factor, Lock told audience members at the California Animal Nutrition conference in May. The risk of milkfat depression can also be increased when there are changes in how the diet is presented to the cow.

"Don't expect one dietary factor to be the answer," he says. "You can be on the 'edge' of milkfat depression and be pushed over by one small diet change. Don't misinterpret that diet change as evil."

There are three predominant ways by which the diet can impact the risk of milkfat depression:

  • Increasing substrate supply of 18-carbon unsaturated fatty acids.
  • Altering the rumen environment and biohydrogenation pathways.
  • A change in the rate of biohydrogenation at various steps in the biohydrogenation process.