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The paradigm for dairy cow diets is always changing.
In past times -- when protein was cheaper and abundant, margins were better and environmental issues were not as focused -- the strategy was to feed all that could be justified and then some more to be sure.
With tightening margins, higher feed cost and more attention to environmental consequences, there are opportunities to refocus on just how much or how little protein is needed to sustain high production and returns to the herd. We are seeing dairy producers reducing the protein levels in their rations by 2% of the diets or more while maintaining production and performance.
Researchers, Extension personnel, feed consultants and feed advisers are taking a new look at not just reducing protein levels in the diets, but how to better manage matching the cow's fundamental protein or nitrogen requirements with her needs. The goal: to improve the efficiency of the protein and reduce the excretion of the excess or unused protein as nitrogen in the manure. The potential results are improved margins and a reduced environmental impact.
Establishing the animal's protein requirements is a process that continues to evolve through research, new models and ration systems. At one time, the concept of crude protein was fundamental to all protein decisions and calculations. The idea was that crude protein is 16% nitrogen and thus, measuring the feed's nitrogen times 6.25 results in the percentage of crude protein. That concept has held true for more than the past century.
What has developed is a greater and better understanding of what makes up that protein requirement and how those protein fractions are used by the modern dairy cow. The application of all that knowledge is encompassed in the modern dairy ration program that resides in the computer that you or your feed adviser may be using.
The on-farm challenge is to utilize this knowledge base, along with the other technologies and management strategies on your farm, to narrow the allowance for diet protein to the cow's needs.
Here are some steps to help you meet that challenge:
- Make sure you understand the concept so you can reduce the allowance for errors in the program and minimize errors in application.
- Use a well-planned system for accurate and trusted feed analysis. Feed analysis should be representative, repeatable, regular and reliable. The system should be technically complete, matching the protein components that are used in your feed programming. Your feed testing program should include all the forage and concentrate portions of your diets.
- Have a good system for feed inventory control. You need to know how much, where it is and how long it will last for each of the forages that you intend to feed.
- Have a system for knowing and adjusting the dry matter content of all your feeds. Dry matter content is the biggest and most frequent variable in your bunk stored feeds. Day-to-day weather conditions will cause significant variation in dry matter and consequent changes in the total mixed ration.
- Make sure you understand and correctly utilize your ration computer programs. Know their limits and opportunities and be able to deal with the details. There are several programs supported by university research and the National Research Council. Many of the proprietary programs are based on those concepts. All of them have some limits and strong points. It may not work to mix programs and all the components of the ration need to work together.
- At the operational level, weigh and mix accurate rations. An extra hundred pounds dumped in the mixer is expensive, and to be short a few pounds of a concentrated ingredient just does not work. Feed multiple groups to be able to bore into the tighter diet standards. Feeding to the high end of a large group overfeeds everyone else.
- Learn to use the milk urea nitrogen (MUN) test as a monitoring tool. High MUN is a good indication of wasted or misaligned protein in the diet. MUN above 16 mg/dL is an indication of excess nitrogen in the diet, and below 10 mg/dL indicates a possible shortage. A good target is 12 to 14 mg/dL.
Practically Dropping Protein of Diets to Reduce Nitrogen Excretion