Simply increasing the crude protein content of your close-up dry cow rations may not bring about an increase in post-partum milk production.

Bill Chalupa, dairy nutritionist at the University of Pennsylvania, says metabolizable protein — not crude protein — is the key. That was demonstrated recently in two articles in the Journal of Dairy Science — one in June 1998 and one in March 1999.

In the June 1998 article, researchers at Penn State University found no significant differences in milk production when late-gestation cows were fed diets containing 10.6, 12.7 and 14.5 percent crude protein. Because the high-crude protein diets contained extra soybean meal, which has a high degree of rumen degradability, metabolizable protein only increased 10 percent to 15 percent in comparison to the low-crude protein ration.

In the other article, Washington State University researchers fed close-up dry cows rations with 11.7, 15.6 and 20.6 percent crude protein. The higher-protein rations contained ingredients with high rumen bypass and excellent balances of amino acids. Thus, metabolizable protein increased 55 percent to 76 percent compared to the low-crude protein ration. Although not statistically significant, cows fed the highest-crude protein ration produced 6.4 pounds a day more milk than cows fed the lowest-crude protein ration.