Is there room in the dairy ration for grass silage?

Intensively managed grass or grass/alfalfa mixtures can add moderate levels of forage fiber to the dairy ration.

At the Great Lakes Regional Dairy Conference held in February 2011 in Frankenmuth, Mich., Dan Undersander from University of Wisconsin presented on the value of grass/alfalfa silage mixtures for dairy cattle. Traditionally, grass has not been incorporated into dairy rations because of the high neutral detergent fiber (NDF) content but there may be a place for high-quality grass silages in diets for formulated with high-quality corn silage and alfalfa silage.

A ration for a group of maintenance cows with high quality corn silage and alfalfa silage may be too short on fiber to maintain a healthy rumen environment, resulting in the need to add higher fiber forages to the diet. Grass or grass/alfalfa mixtures can be managed to maintain protein concentrations in the silage and can add moderate levels of NDF forage fiber.

A key to obtaining alfalfa-grass mixtures for high quality forage is to maintain stands that are 30% to 40% grass. If alfalfa/grass mixed fields are in production for more than three years, the proportion of grass in the field will rise and the nitrogen (N) fixation of the legume will not be able to meet the N needs of the grass resulting in decreased forage yield. When utilizing a field of alfalfa/grass mix for lactating dairy cow feed, ensure that there is consistency in the forage by routine sampling of the silage.

Use care in selecting your grass variety, as there may be more variation within variety than between varieties. Select grass variety based on yield, seasonal distribution of yield, winter hardiness, maturity, and rust resistance.

Undersander also discussed agronomic reasons for adding grasses to alfalfa fields, including:

  • Increased seeding year yields
  • Wider harvest window for second and later cuttings – most grasses do not head out after first cutting
  • Faster drying than pure alfalfa or pure grass
  • Somewhat less winter kill or injury to alfalfa stand if selected for winterhardiness
  • Ability to apply manure to stands with less traffic damage and stand loss

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