EFFECTS OF SUPPLEMENTAL HAY ON CONSUMPTION OF LOW AND MEDIUM DRY MATTER CORN SILAGE BY HIGH-PRODUCING DAIRY COWS

Abstract

The effects of supplementing low (23.9%) dry matter (DM) and medium (28.9%) DM corn silage roughage rations fed ad libitum to high-producing dairy cows, with orchard grass hay at 0.7% of their body weight on milk production and composition, was determined in a double reversal feeding trial using 24 lactating cows. Cows fed medium DM corn silage consumed 15.2% more DM/100 kg body weight daily than those cows fed low DM silage (P < 0.05). Supplemental hay fed with either low or medium DM silage resulted in equal consumption of total forage DM/100 kg body weight by cows on the two treatments. Each kilogram of hay DM consumed by cows offered low DM corn silage reduced silage DM intake by 0.47 kg, whereas hay DM intake reduced silage DM intake by 0.79 kg for cows offered medium DM silage. Daily production of 4% fat-corrected milk (FCM), percent nonfat solids (SNF), and daily body weight gain were lower for cows consuming low DM corn silage than for those on the other treatments (P < 0.05). Cows consuming low DM corn silage plus orchard grass hay at 0.7% of their body weight produced milk at the same level and of similar protein, lactose, and SNF content as those fed medium DM silage plus hay. Supplemental hay fed with medium or low DM corn silage increased FCM production over feeding silage alone, independent of DM or moisture content of the silage fed (P < 0.05).