Partial Replacement of Concentrate by High Quality Hay for Cows in Early Lactation

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Abstract
The effect of partial replacement of concentrate with high quality hay in the diet of lactating cows was evaluated. Basal forage components were long alfalfa hay and corn silage. In Trial 1, 30 Holsteins in early lactation were fed concentrates containing a ground legume-grass hay at 0, 20 and 33%. There were no differences in intake of dry matter, yields of milk or milk components and changes in body weight. Glucose, urea nitrogen and free fatty acids in blood and volatile fatty acids in rumen contents differed. In trial 2, six Holstein and 3 Brown Swiss cows were blocked into three groups in a 19 day measurement of digestibility and rate of passage of feeds. Alfalfa-grass hay in ground or chopped form replaced 0 and 20% of concentrate. In a marker meal, concentrate portion was stained with basic fuchsin and the long hay portion with crystal violet. There were no differences in apparent digestion coefficients from concentrate replacement or form of forage. There were no marked differences in retention time for the long hay component. Concentrate with 20% substitution of ground forage passed through the digestive tract more rapidly than 0% substitution or that containing 20% chopped forage.