Performance of Lactating Dairy Cows Fed Diets Based on Sorghum and Ryegrass Silage and Different Energy Supplements

Forty-one Holstein cows were used in a 7-wk completely randomized trial to evaluate the effect of forage combination and energy source on performance. Treatments were arranged as a 2 x 3 factorial to include 2 combinations of sorghum silage and ryegrass silage (50:50 or 75:25) and 3 energy sources: ground corn, and corn hominy feed, or a 50:50 blend of ground corn and corn hominy feed. Diets were formulated to contain similar concentrations of CP, NDF, and energy and were fed once daily. No interactions of forage combination and energy source were observed except for milk protein percentage, which was highest when the 50:50 diet was supplemented with the blend of ground corn and hominy feed, but lowest when the 75:25 diet supplemented with the blend of ground corn hominy feed. Dry matter intake and milk yield were similar among treatments. Yield of milk fat, energy-corrected milk, and efficiency of milk production were higher with 75:25 compared with 50:50 forage combinations. Energy supplement did not influence milk composition. These results indicate that production is improved when greater proportions of sorghum silage relative to ryegrass silage are fed.