|Maignan, Samuel - ECOLE SUPERIEURE D'AGRIC|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2001
Publication Date: N/A
Interpretive Summary: Alfalfa often is fed to dairy cows as silage rather than hay because silage harvesting requires much less manual labor. Most of the protein in alfalfa is broken down in the silo to nonprotein nitrogen (NPN) which is used less efficiently than intact protein. Red clover silage contains less NPN than alfalfa and, as a result, may be a better forage. Two feeding studies were conducted using alfalfa and red clover harvested during two different years. Red clover silage contained less protein than alfalfa silage but only 70% as much of that protein was present as NPN. The three diets fed in trial 1 contained equal dry matter from alfalfa, red clover, or red clover and alfalfa grown together; soybean meal was added to equalize dietary protein. Although cows ate less of the red clover diets, replacing alfalfa with red clover did not reduce yield of milk, protein or lactose (milk sugar). The four diets fed in trial 2 contained equal total silage from alfalfa, red clover, or alfalfa or red clover plus corn silage; soybean meal was added to equalize protein but the diet with only alfalfa forage contained 2% more protein. As in trial 1, cows ate less of the red clover diets and replacing alfalfa with red clover resulted in equal yield of milk, protein, and lactose. However, cows produced more milk and protein on red clover plus corn silage. In both trials, milk yield per unit feed eaten, milk protein yield per unit of protein eaten and feed digestibility and energy content were greater when red clover replaced alfalfa. These results indicate that protein and energy in red clover silage are both used more efficiently than that in alfalfa silage. This research will benefit dairy farmers by allowing them to reduce nutrient excretion by replacing dietary alfalfa with red clover.
Technical Abstract: Two Latin square trials, with 21 or 24 multiparous lactating Holstein cows, compared the feeding value of red clover and alfalfa silages harvested over two years. Red clover containing silages averaged 2 percent lower in crude protein (CP) and more than 2 percent lower in neutral and acid detergent fiber than did alfalfa silage. In Trial 1, diets were formulated to 60% dry matter (DM) from alfalfa, red clover silage, or alfalfa plus red clover silage (grown together); CP was adjusted to 16.5% with soybean meal and the balance of the DM was from ground high moisture 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-red clover, yield of milk and milk components was not different among diets. In Trial 2, four diets with rolled high moisture shelled corn were formulated to 60% DM from alfalfa or red clover silage, or 48% DM from alfalfa or red clover silage plus 12% from corn silage DM. The 60% alfalfa diet had 18.4% CP and the other three diets averaged 16.5% CP. Nonprotein N in red clover silage was 62% of that in alfalfa silage. Intake of DM was 2 (no corn silage) and 1 kg/d (plus corn silage) less on red clover. Yield of milk and milk components were similar on the first three diets; however, yields of milk, total protein, and true protein were higher on red clover-corn silage. Replacing alfalfa with red clover improved feed and N efficiency and digestibility of DM, organic matter, fiber, and hemicellulose in both trials. Net energy of lactation computed from animal performance was 18% greater in red clover than alfalfa. Data on milk and blood urea and N efficiency suggested better N utilization on red clover.