EFFECT OF WHEAT SILAGE MATURITY ON DIGESTION AND MILK-YIELD IN DAIRY-COWS

The effect of wheat crop maturity on diet digestibility and lactational performance by high yielding dairy cows was measured in an 8-wk lactation experiment under commercial dairy herd conditions. Friesian cows (n = 168) were fed 7 kg of DM from either early or late cut wheat silage (harvested at middle flowering or at the end of the milk stage). Each diet contained 33% NDF, 18.5 percentage units of which was from forage. Feed intake (22 kg/d of DM) and DM digestibility (63%) of the two diets were similar. Dietary NDF digestibility was higher in the early cut silage (45.7) than in the late cut silage (41.3%). Although DM from the two silages was similarly degraded in the rumen, degradability of NDF was 24% higher in the early cut silage. Yields of milk and milk energy in the cows receiving the early cut silage were higher than those of cows receiving the late cut silage by 3.2 kg/d and .85 Mcal/d, respectively. Apparently, NDF content is an inaccurate predictor of energy content of wheat silage.