Comparison of 'Mott' dwarf elephantgrass silage and corn silage for lactating dairy cows

'Mott' dwarf elephantgrass (Pennisetum purpureum) is a tropical perennial bunchgrass growing to an undefoliated height of 1.5 m. Twelve lactating Holstein cows averaging 72 DIM were arranged in three replications of a 4 X 4 Latin square. Cows were fed a dietary forage to concentrate ratio of 48:52. Chopped alfalfa (Medicago sativa) hay made up 10% of DM. Dietary treatments were corn (Zea mays) silage and dwarf elephantgrass silage fed at DM ratios of 38:0, 20:18, 10:28, and 0:38. Dry matter intake responded in a quadratic fashion (19.1, 19.4, 18.9, and 17.2 kg/d for diets 38:0 to 0:38). Digestibility (determined with chromic oxide marker) of dietary NDF and ADF increased linearly with increasing concentration of elephantgrass in the diet. Milk and 4% FCM yields tended to decrease slightly with increasing dietary elephantgrass. Ruminal pH and molar percentage acetate increased linearly, whereas ammonia N declined linearly with increasing elephantgrass in the diet. In situ extents and rates of DM and cellulose digestion were higher for elephantgrass than for corn silage. Dwarf elephantgrass silage appears to be of high quality with potential for high DMI. When substituted for corn silage, it resulted in only a small decrease in milk yield