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 cubed 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 degrees 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 lactating 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 preservation 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 unexpectedly low for cows fed long hay (2.90%); therefore, cubing only decreased 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 milk production compared with effects of uncubed hay or silage.