Voluntary Intake and Digestibility of Legume and Grass Diets Fed to Lactating Cows and Growing Wethers

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Abstract
Two complete mixed diets (77% forage, 23% concentrate) were fed to 20 Holstein cows during the 2nd third of lactation and to 7 wether sheep to compare voluntary intake and digestibility of the 2 diets and to compare the utilization of the diets in the 2 animal species. Diet neutral detergent fiber percent, and as-fed bulk density (kg/l) for the alfalfa hay diet (alfalfa diet) were 42.3 and .20. Respective values for the orchardgrass diet (grass diet) were 47.5 and .12. Dry matter intake of cows fed the alfalfa diet (164 g/kg body wt.75) was greater, whereas vol intake (837 ml/kg body wt.75) was less than the respective values (136 g/kg body wt.75 and 1097 ml/kg body wt.75) for the grass diet. Daily intakes of digestible energy and neutral detergent fiber and production of 4.0% fat-corrected milk for the alfalfa and grass diets were not different. Comparable intakes of dry matter and vol by sheep for the alfalfa diet were 63 and 323, and for the grass diet were 64 and 519. Diet digestibility was lower in cows than in sheep. Estimates of diet digestible energy from National Research Council tables overestimated actual digestible energy of the high forage diets fed ad lib to lactating cows.