ALFALFA SWEET SPOT IN DAIRY RATIONS?
by Mike Rankin
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VER the past 30 years, alfalfa has lost market share to corn silage in dairy cow diet formulations. Multiple reasons have been cited for this shift, including lower alfalfa yields, winterkill risk, feed variability, and high production expenses. At the same time the rapid move to corn silage has been occurring, growers and nutritionists still recognize that alfalfa has many positive agronomic, environmental, and feeding attributes.
A perfect pair “From a nutritional perspective, it would be hard for us to find two forages that are more complementary with each other than alfalfa and corn silage,” said Rick Grant while speaking at the Midwest Forage Association’s Symposium 2022 in Wisconsin Dells, Wis. The president of the Miner Research Institute in Chazy, N.Y., noted that the starch and its degradability in corn silage matches “so well”
with the amount of protein and the solubility of that protein in alfalfa. In continuing to contrast alfalfa and corn silage, Grant noted that the “Queen of Forages” has less neutral detergent fiber (NDF) and higher undigestible NDF (uNDF), but the rate of digestion is much faster than corn silage. Alfalfa’s fiber is more “fragile,” and it breaks apart into cuboidal particles that are easy to swallow and pass through the rumen. As a result, alfalfa proves to be less filling than grasses such as corn silage, allowing for higher dry matter (DM) intakes. “Alfalfa has great buffering attributes for the rumen,” Grant said. “It contains more sodium and potassium, has a higher dietary cation-anion difference (DCAD), and overall, we think that alfalfa may help to stabilize rumen pH and boost milkfat in higher corn silage rations.” Alfalfa is also a much better source of lysine, an essential amino acid, than corn silage. The dairy nutritionist noted that alfalfa’s value as a protein source is
Mike Rankin
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certainly greater in these times of high soybean meal prices, but Grant also thinks there is the ongoing potential to optimize the interaction between the rumen degradable protein of alfalfa and the starch from corn silage to enhance microbial protein synthesis. However, he warned that other ration ingredients need to be formulated in such a way to capitalize on this synergy.
Is more alfalfa warranted? Grant and his research team decided there was a need to re-evaluate alfalfa inclusion in modern, high-producing dairy cow ration formulations that often have high concentrations of forage fiber. They wanted to determine if more alfalfa can successfully be fed in dairy rations and if there was a benefit in doing so. The feeding trial was completed in 2021 using 105 Holstein cows. Each treatment diet was formulated for 62% forage and the same predicted metabolizable protein, although in the end the higher alfalfa diets provided a little more metabolizable protein. Inclusion
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