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December 2015
For a dairy ration to be balanced correctly, all amino acid needs must be met. The ability of a cow to grow or to produce milk is determined by the most limiting amino acid. Thus, amino acids that are supplied over the limit are wasted. Supplying the correct amounts, without too many excesses, requires some finesse.
As we saw earlier, corn DDGS would need to be supplied at 243 percent of the protein requirement to meet the cow’s needs for lysine. However, this ingredient is an excellent source of leucine, an amino acid that is inadequate in both canola meal and cottonseed meal. Therefore, to help to combat the protein overage issue, canola meal and cottonseed meal can be blended with corn DDGS. The exact ratio of canola to corn DDGS or cottonseed to corn DDGS can be determined by the ration formulator.
Microbial protein is an important part of the amino acid equation, as it provides an excess of all amino acids except histidine and leucine. Microbial protein complements the low threonine content of corn gluten meal and cottonseed meal.
When balancing the ration, be sure to consider which ingredients complement each other well.
The balance of essential amino acids that need to be supplied from supplemental protein sources varies with the diet. Forages and grains are also sources of amino acids, contributing varying amounts of essential amino acids to support the cow’s needs.
Feed formulation programs allow requirements for essential amino acids to be evaluated. By having multiple protein sources available, the blend that best meets needs can be constructed to minimize overages, improving efficiency and costs.
To demonstrate this,research showed that blending canola meal (2/3) with high-protein DDGS (1/3) allows cows to produce more milk and milk protein than canola meal alone. By producing more milk protein, less ration protein was wasted.
