Strategies to Improve Milk Yield of Lactating Dairy Cows Fed Red Clover Silage

Two trials were implemented to explore nutritional strategies to improve lactation performance of dairy cows fed red clover silage (RCS)-based diets. In Trial 1, 18 earlyto midlactation dairy cows were assigned to a replicated 3 × 3 Latin square trial design and fed diets containing forage bases of all RCS, a mixture of RCS and brown midrib corn silage (BMR), and a mixture of RCS and normal corn silage (NCS). Treatment diets were fed for 28 d and contained similar amounts of protein; treatments were formulated to be high in forage fiber so that utilization differences by the lactating cows could be expressed readily between the forage feeding schemes. Cows fed diets containing BMR and NCS consumed significantly more DM and produced approximately 1.5 kg more milk than cows fed diets containing all RCS. Cows fed diets containing all RCS also produced less true protein (TP) and nonprotein nitrogen (NPN) in milk. Cows fed BMR ate more DM and NDF than did cows fed diets containing NCS, but the increased DMI did not result in improved lactation performance. In Trial 2, 16 earlyto midlactation dairy cows were assigned to a replicated 4 × 4 Latin square trial design and fed RCS-based diets containing moderate (MCP; 17.9%) or high (HCP; 19.5%) levels of CP with or without 4.2% of DM as supplemental dextrose. Cows fed diets containing HCP had increased DMI and milk production when compared with cows fed MCP. In addition, cows fed diets containing HCP significantly increased the CP, TP, NPN, and solids-no-fat (SNF) content of their milk. Yield of all milk components measured was increased by diets containing HCP. Supplementing the diets of cows with 4.2% dextrose had some minor negative effects on milk casein and TP yields, but results were biologically