Editor's note: Jim Linn is an Extension dairy nutrition specialist and chairman of the Department of Animal Science at the University of Minnesota. He also authors Dairy Today's Nutrition column.
At what level of milk production does balancing amino acids become important?
Linn: In theory, it pays at any level of production because we can decrease the amount of total crude protein in the diet, increasing the efficiency of nitrogen usage. However, I would think in most herds the early-lactation and high-production groups will benefit most from amino acid balancing. If you needed a number, I would say 75 lb. of 3.8% milk or higher.
Where do you see the biggest benefit?
Linn: When herds are one-dimensional protein supplement feeding. In herds where there are several protein sources being fed, amino acid balancing is probably occurring by default and the response to amino acid balancing will be limited.
Best opportunities are when the protein content of the diet is high and amino acid balancing can reduce it or when the protein content of the diet is already low and the right amino acid balance can increase milk production and components. Herds that are balanced close to NRC requirements for protein and have a couple of different protein sources are probably the least likely to see a benefit.
In the rations you typically work with, do you feel lysine or methionine is first limiting?