Voluntary Alfalfa Hay Wafer Intake by Lactating Dairy Cows Fed Varying Concentrate Amounts

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Abstract
Vohmtary hay wafer intake of 20 first- lactation Holstein eows fed 20, 35, 50, 65, or 80% of their estimated net energy requirements as a concentrate mix was measured during a 36-wk feeding trial. Mean hay wafer dry matter intake de- dined .78 kg for eaeh 1.0 kg of concen- trate dry matter eonsumed by the cows. However, eoneentrate intake per se ac- counted for only 43% of the variability in voluntary hay wafer intake. Multiple regression models which in- eluded as variables concentrate treat- ment, maintenance net energy require- ment, milk energy, and week of test aeeounted for 73% of the variation in voluntary hay wafer intake. Depressed milk fat percentage oc- curred consistently among higher pro- ducing cows receiving 50% or more of their energy requirements as a eoncen- trate mix whereas lower producing cows gave milk with normal fat composition regardless of ration. Milk fat percentage was normal from all cows fed 20 to 35% of their energy requirements as eoneen- trates.