With alfalfa production declining and corn silage becoming a more prominent forage source, dairy producers face a new challenge in formulating diets for their high-producing dairy cows. A new article in Applied Animal Science offers valuable insights for dairy producers and nutritionists navigating this shift. Written by lauded nutrition expert William (Bill) Weiss, PhD, of The Ohio State University, the article explores how soy-based feedstuffs can be effectively used to maintain optimal nutrition and milk production with these changing feeding practices.

"This Perspective and Commentary article," explained David Beede, PhD, editor in chief of Applied Animal Science, "discusses the nutritional strategies for the use of soy-based feedstuffs in diets based on high corn silage fed to high-producing dairy cows. Generally, more supplemental protein is needed such as from soy-based ingredients, but often total crude protein concentration of the diet can be reduced."

Weiss explained that numerous dietary changes must occur when corn silage replaces all or some of the alfalfa in a cow's diet. "Inclusion rates of protein supplements need to increase and dietary starch concentrations usually need to decrease."

Alfalfa hay or silages fed to dairy cows usually average 20% to 22% crude protein, whereas corn silage averages much lower with 7% to 8% crude protein. And depending on production levels, stage of lactation, feed costs, and other factors, lactation diets generally are 14% to 18% crude protein. How can producers fill that nutritional gap? The article outlines recent research demonstrating that soy-based ingredients, rich in metabolizable protein--the usable protein for a cow--emerge as a highly effective solution.

How does it work? Soybean meal's uniquely effective protein profile, explained Weiss. "The rumen degradable protein fraction of soy is made up almost entirely of amino nitrogen allowing efficient use by a cow's rumen microbes, and soy's rumen undegradable protein is highly digestible."

This means that the total crude protein concentration can be reduced in diets with high soy-protein content. Weiss said that as the concentration of alfalfa decreases and soy protein increases, less overall crude protein is needed to meet a high-producing cow's metabolizable protein requirements.

He further addressed the potential risk of acidosis associated with high starch levels when corn increases in a cow's diet. Soyhulls, with their high digestibility and low starch content, are identified as a valuable feedstuff for mitigating this risk by replacing some of the dietary starch.

"Overall, the research demonstrates that diets containing minimal or no alfalfa can achieve similar milk yield and milk components with less starch and protein compared with traditional alfalfa-based diets," said Weiss. "This is achieved through strategic inclusion of soy products."

The article concluded by providing practical applications of these findings via three diets containing decreasing concentrations of alfalfa silage, showcasing how soy-based ingredients can effectively address the nutritional needs of high-producing dairy cows fed diets based on high corn silage.