Current Progressive Dairy digital edition

1008 PD: Balancing amino acids in dairy nutrition from concept to practice

Spence Driver Published on 30 June 2008

Balancing amino acids in dairy rations to enhance protein efficiency is similar to the ideal protein concept used by poultry and swine nutritionists for many years.

The premise of the ideal protein concept is to increase the concentration of the most limiting amino acids in the diet and all other amino acids will be used more efficiently. Thus, we can balance diets with lower concentrations of crude protein.



The benefits of the ideal protein concept are to:

1. Reduce excessive quantities of expensive rumen undegradable protein (RUP) sources.

2. Reduce nitrogen excretion. Cows waste valuable energy when converting excess nitrogen and amino acids to urea for elimination.

3. Improve the environment. Dr. Glenn Broderick’s USDFRC research shows that nearly all of the nitrogen in the extra dietary protein that was not captured as milk protein ended up in the urine, the form that causes the most problems in the environment.

4. Free up space in the diet for other nutrients, primarily fiber and energy.


First limiting amino acids are those that are in shortest supply relative to requirements. Methionine and lysine are generally considered the first limiting amino acids for lactating dairy cows. They are most limiting because a small number of feeds have concentrations of either lysine or methionine that are as high as the concentrations observed in milk and bacterial protein produced in the rumen.

There is still some reluctance in the dairy industry to put the principles of amino acid nutrition into practice. I continue to hear comments as follows: it’s too expensive, production isn’t high enough, components are already good, lowering protein in the diet will drop production, just a story to sell protected amino acids, don’t know how to use the tools available and more research is needed.

More research is needed before dairy cattle diets can be balanced for amino acids with the precision possible for non-ruminants. Nevertheless, sufficient progress has been made to make improvements in a predictable fashion that allows for improved utilization of protein and therefore, improved efficiency.

Computer models have advanced to the point of predicting how well a diet supplies protein and amino acids to meet the requirements of lactating dairy cows. Dr. Chuck Schwab, University of New Hampshire, says, “Although these models are far from perfect, they represent big steps forward in evaluating diets for rumen degradable protein (RDP), RUP and amino acids and have been useful for improving the efficiency of conversion of feed crude protein to milk protein on many dairy farms.”

Here are some considerations when using the protein and amino acid model:

1. Make sure animal production and feed inputs are accurate.


2. Don’t short-change cows on rumen degradable protein.

3. Don’t overfeed RUP.

4. Strive to maximize concentrations of both lysine and methionine while maintaining a 3:1 ratio.

There are many good reviews in the literature summarizing the benefits of balancing amino acids in lactating cow diets. A summary of seven trials looking at milk in the first third of lactation to increase lysine and methionine concentrations in typically fed dairy rations showed an average:

• 1.54 pounds per day increase in milk yield

• 0.16 percent boost in milk protein concentration

• 0.17 pounds higher milk protein yield

• 0.02 percent gain in milk fat concentration

• 0.10 pounds increase in milk fat yield.

While amino acid formulation looks good in theory, does it work on the farm? We have been evaluating amino acid nutrition for almost ten years.

Originally, we ran a commercial field trial in conjunction with the University of Wisconsin. Nineteen high-yielding dairy herds participated (rolling herd average 23,606 pounds milk). By balancing for amino acids, we were able to reduce crude protein 17.6 percent to 16.8 percent (dry matter basis). The focus of the trial was to lower dietary crude protein and feed cost without affecting performance. A trend for improvement in protein concentration was the only difference due to amino acid balancing. We saw no other change in production, yet feed costs were reduced as a result of the reduced dietary protein.

More recently, Vita Plus has been using the National Research Council (NRC) model to fine-tune rations to improve protein efficiency.

We recently reviewed the success Vita Plus is having with amino acid nutrition. A summary of 10 herds that our nutrition staff modeled for amino acids is shown in Table 1. Like any new technology, it is never 100 percent successful. However, I am excited by the high degree of success we are having with this technology.

For a marginal increase in ration costs, milk performance, particularly milk composition, can be improved, increasing milk returns significantly with the current high component pricing, especially for milk protein.

What does amino acid balancing have to offer? Balancing for amino acids can benefit dairy producers in a number of ways:

• Raise production of both milk yield and components at minimal cost.

• Lower total protein content of the diet and thus, lower diet cost.

• Reduce nitrogen excreted into the environment.

• Provide more predictable milk performance.

• Improve margins. PD

Spence Driver
Dairy Technology
Service Manager for
Vita Plus

Are there certain commodity market conditions (i.e., high feedstuff prices) that make amino acid balancing more expensive? Or in other words, can balancing a ration for amino acids be done effectively regardless of commodity prices?

When we started modeling diets we were dealing with low-cost feed proteins and milk protein prices were averaging $2.40 per pound. We were consistently seeing returns greater than 2-to-1. Currently, we are dealing with historically high feed protein prices and also milk protein prices greater than $4 per pound and seeing an average response better than 3-to-1.

Worst-case scenario is if feed prices remain high and milk prices drop. We may not be able to offset higher ration costs if we try to maximize the production response.

However, we do have options available. Modeling gives us the opportunity to look at multiple scenarios based on ever-changing market conditions. Three modeling scenarios have been used successfully when amino acid balancing. They are:

1. Maximize metabolizable protein, lysine and methionine to maximize milk volume and components at a significant increase in ration cost.

2. Optimize metabolizable protein, lysine and methionine to maintain milk volume but still increase milk components with only a modest increase in ration costs.

3. Modulate metabolizable protein and target lysine and methionine (maintain ratio) to maintain production and maintain or decrease feed costs.

Scenario three may be the best option when market conditions do not appear favorable. I modeled a diet, lowered feed costs five cents per head and saw a 0.04 percent increase in milk protein.

Because of the different options available, I believe we can model diets for amino acids cost effectively regardless of commodity prices.

References omitted but are available upon request at