Production of lactating dairy cows fed alfalfa or red clover silage at equal dry matter or crude protein contents in the diet

Two Latin square trials, using 21 or 24 multiparous lactating Holstein cows , compared the feeding value of red clover and alfalfa silages harvested ov er 2 yr. Red clover silages averaged 2 percentage units lower in crude prot ein (CP) and more than 2 percentage units lower in neutral detergent fiber and acid detergent fiber than did alfalfa silage. In trial 1, diets were fo rmulated to 60% dry matter (DM) from alfalfa, red clover silage, or alfalfa plus red clover silage (grown together); CP was adjusted to about 16.5% by adding soybean meal, and the balance of dietary DM was from ground high mo isture ear corn. Nonprotein N in red clover and alfalfa-red clover silages was 80% of that in alfalfa silage. Although DM intake was 2.5 and 1.3 kg/d lower on red clover and alfalfa plus red clover, yield of milk and milk com ponents was not different among diets. In trial 2, four diets containing ro lled high moisture shelled corn were formulated to 60% DM from alfalfa or r ed clover silage, or 48% DM from alfalfa or red clover silage plus 12% DM f rom corn silage. The first three diets contained 2.9% soybean meal, and the red clover-corn silage diet contained 5.6% soybean meal; the 60% alfalfa d iet contained 18.48 CP, and the other three diets averaged 16.5% CP. Nonpro tein N in red clover silage was 62% of that in alfalfa silage. Intake of DM was about 2 (no corn silage) and 1 kg/d (plus corn silage) lower on red cl over. Yield of milk and milk components was not different among the first t hree diets; however, yields of milk, total protein, and true protein were h igher on red clover-corn silage with added soybean meal. Replacing alfalfa with red clover improved feed and N efficiency and apparent digestibility o f DM, organic matter, neutral detergent fiber, acid detergent fiber, and he micellulose in both trials. Net energy of lactation computed from animal pe rformance data was 18% greater in red clover than alfalfa. Data on milk and blood urea and N efficiency suggested better N utilization on red clover.