Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2000
Publication Date: N/A
Citation: Interpretive Summary: Alfalfa is often fed to dairy cows as silage rather than hay because harvesting silage requires much less manual labor. A large proportion of protein in alfalfa is broken down in the silo to nonprotein nitrogen. This form of nitrogen is used less efficiently than intact protein. Red clover silage contains less nonprotein nitrogen than alfalfa and may be a better forage for dairy cows. We conducted three feeding studies to compare the feeding value of red clover and alfalfa silages harvested during three different years. Both contained similar amounts of fiber. Red clover contained somewhat less protein but only two-thirds as much was in the form of nonprotein nitrogen as alfalfa. Four diets, each with the same amount of forage, were fed in every trial: two with alfalfa silage and two with red clover silage. One alfalfa and one red clover diet in each trial was supplemented with fish meal--effective protein source for cows. Replacing alfalfa with red clover reduced overall yield of milk, fat, protein and lactose. Replacing dietary alfalfa with red clover improved weight gain, milk yield per unit feed intake, and dry matter digestibility; net energy in red clover silage was 10% greater than alfalfa silage. Also, milk and blood urea were lower on red clover, suggesting that its protein was more effective. This research indicates that protein and energy in red clover silage are both used more efficiently than that in alfalfa silage. If intake of red clover could be improved to equal that of alfalfa, then feeding cows red clover would reduce nitrogen levels in manure and nutrients lost to the environment. Continued research will benefit consumers and the environment.
Technical Abstract: Three Latin square trials with multiparous lactating Holstein cows (4 in each trial with ruminal cannulae) compared the feeding value of red clover and alfalfa silages harvested over three years. Overall, the forages contained similar amounts of NDF and ADF; however, red clover silage contained more hemicellulose, less ash and CP, and only 67% as much NPN as a proportion of total N, as did alfalfa silage. Diets were formulated with equal dry matter (DM) from alfalfa or red clover silage; overall DM means were 65% forage, 33 or 30% ground high moisture ear corn, and 0 or 3% low solubles fish meal. Diets fed contained (mean CP): 1) alfalfa (17.8% CP); 2) red clover (15.1% CP); 3) alfalfa plus fish meal (19.6% CP); and 4) red clover plus fish meal (16.9% CP). Performance varied somewhat among trials but milk and protein yield were greater for cows fed alfalfa in two of three trials and weight gain was greater with feeding of red clover in two of three trials. Fat yield and, consistent with higher CP intake, milk ure concentration always were greater for cows fed alfalfa silage; fish meal supplementation always increased fat and protein yield. Overall statistical analysis showed that replacing alfalfa with red clover reduced yield of milk, FCM, fat, protein, lactose and SNF; these effects were related to the 1.2 kg/d lower DM intake on red clover. Replacing alfalfa with red clover improved BW gain, DM and N efficiency, and reduced milk and blood urea and ruminal NH3. Apparent digestibility of DM, organic matter, NDF, ADF and hemicellulose all were greater when red clover was the dietary forage. Forage NEL, estimated from maintenance, mean milk yield and BW change, of alfalfa and red clover silage were, respectively, 1.25 and 1.38 Mcal NEL/kg of DM, indicating 10% greater NEL in red clover.