CHEWING ACTIVITIES AND MILK-PRODUCTION OF DAIRY-COWS FED ALFALFA AS HAY, SILAGE, OR DRIED CUBES OF HAY OR SILAGE

The objective of this research was to compare the effects of dried cub ed hay or silage and long hay or silage on chewing activities and milk production of dairy cows. Second-cutting alfalfa was preserved as hay or wilted silage, and a portion of each forage was dried (hay at 80 d egrees C; silage at 175 degrees C) and cubed (5 x 3 x 3 cm). The crude protein effective degradability of forages measured in sacco was (dry matter basis) hay, 69%; hay cubes, 70%; silage, 87%; and silage cubes , 82%. Forages were fed in a replicated 4 x 4 Latin square to eight la ctating Holstein cows. The diets, consisting of 45% forage (dry matter basis), were fed in a 2 x 2 factorial arrangement; hay or silage was unprocessed or cubed. The dry matter intake were about 2.6 kg/d lower for cows fed silage than for cows fed hay, but the method of preservat ion did not affect production or fat content of milk or chewing times. Cubing decreased dry matter intakes of both forages by about 1.5 kg/d (2.90%), resulting in a 3.5 to 4.3% reduction in milk production and a 52 to 62% reduction in rumination time. The milk fat content was une xpectedly low for cows fed long hay (2.90%); therefore, cubing only de creased the milk fat content of cows fed silage (silage, 3.34%; silage cubes, 2.86%). Silage offers a viable alternative to hay for cubing. However, for dairy cows receiving high concentrate diets, cubed hay or silage as the sole source of forage might lower intake and reduce mil k production compared with effects of uncubed hay or silage.