Alfalfa has one of the highest feeding values of forages. It has always been perceived as an excellent source of protein, but is sometimes underestimated as an energy source. A ton of alfalfa hay contains as much total digestible nutrient (TDN) as 25 bushels of corn (and as much protein as two-thirds ton of soybean meal). Beef cows are more likely to be fed rations more deficient in energy than in protein, particularly during the last trimester of pregnancy and postpartum (after calving). A beef cow needs high energy hay to regain body weight after calving, produce milk for her calf, and rebreed in 40 to 90 days after calving.

Some grass hays may be as high in digestible dry matter as alfalfa; however, those hays will be digested slower than alfalfa. As mentioned earlier, some alfalfa hay will pass through the rumen of a beef cow in about one-half the time required by grass hay (36 versus 70 hours). Therefore, animals fed alfalfa hay tend to gain faster, produce more milk, and maintain themselves in better condition than those fed other forages. This increased gain is primarily associated with an increase in intake, and the benefits would be negligible if the alfalfa was limit-fed (controlled intake).