Alfalfa Silage Versus Red Clover Silage or a Mixture of Alfalfa and Red Clover Silage as the Sole Forage for Lactating Dairy Cows

Introduction The large proportion of CP in alfalfa silage (AS) that is present as NPN substantially reduces the efficiency of protein utilization by lactating dairy cows (Nagel and Broderick, 1992). Red clover silage (RCS) typically has a much lower content of NPN than AS (Albrecht and Muck, 1991). In a previous feeding study (Broderick and Sterrenburg, 1996 USDFRC Res. Sum.), we found that DMI and milk yield were greater on AS than on RCS, but this result was confounded by the fact that the CP content of the AS was seven percentage units greater than that of the RCS. Therefore, we repeated the comparison of AS versus RCS as the only forage for lactating cows, but with added solvent soybean meal (SBM) to equalize dietary CP content. Also, a third diet containing silage harvested from a coculture of alfalfa and red clover (AS + RCS) was included in this trial. No supplemental bypass protein was used in this study. Our objective was to compare the lactational performance of cows fed AS, RCS or AS + RCS as their sole source of dietary forage.