Nutrition for the modern dairy cow: what we now know about feeding protein

August 2015

Today’s dairy cow is producing more milk than ever before, and more than was even imagined a generation ago (see graph below). That means that the cow’s requirements for nutrients are higher than ever to achieve that phenomenal production level. Those nutrients are needed to maintain her body condition, produce milk, and finally, produce a calf.

At an ADSA DISCOVER conference, which focused on protein and amino acids, it was noted that ration protein levels have actually been going down while milk production has been paradoxically increasing.

Why have ration protein levels been declining? There are a few reasons:

1. Laboratory techniques to evaluate feed ingredients have evolved, with feed analysis laboratories providing excellent results to the industry.
2. We have improved our knowledge of the feed ingredients that we are using in rations, allowing us to better understand the actual amount of rumen undegraded protein (RUP) that each ingredient provides.
3. Ration formulation guidelines continue to evolve as we learn more about ingredients and nutrient requirements.

Milk urea nitrogen (MUN) is a particularly important tool for practically measuring results and making adjustments to dairy rations. You can use the following MUN criteria to help determine adequate protein levels:

• High milk production and high MUN: Protein is likely being overfed.
• Low milk protein production and high MUN: The wrong protein is being fed to the cows.
• Low MUN: There may not be enough protein in the ration.

While key to dairy nutrition, protein is generally an expensive feed ingredient. Pinpointing the feeding of protein to reduce the level in a diet through a better use of feed ingredients can help lower costs. As our knowledge of ration ingredients continues to evolve, recent research has shown that canola meal is an effective protein source in dairy rations. By producing more milk with less protein, dairy farmers are tackling the issue of environmental stewardship head on, and winning!