Dairy Cows on Pasture

 
The role of pasture in dairy management systems is lessening with the trend to increased production and more intensive operations. The high moisture content of pasture makes it difficult for milking cows to consume the large amounts of feed necessary to support the high levels of production expected.
 
Many dairy producers do, however, effectively utilize pasture as part of their feeding program. Advantages of pasture include improved health and reproduction due to exercise, more efficient use of areas not suited to crop production and reduced feed costs. Concentrate feeding can be reduced when cows are on good quality pasture but pasture cannot substitute for all the concentrate in a ration. It has been estimated that without any grain, good cows on excellent pasture can produce about 75% as much milk as when grain is fed. If medium quality pasture is fed alone, milk production will only be about 60% that achieved with grain supplementation.
Some of the disadvantages associated with pasture are increased maintenance requirement due to grazing activity, increased heat and fly problems, wasted feed due to trampling and lack of uniform feed quality. Changes in quality and difficulties in estimating pasture intake make ration programming more difficult. Consider the following when pasturing your cows.
  1. Ensure pasture is young, actively growing and in good supply. Begin grazing when tall-growing, cool-season grasses and legumes are 8-10 inches tall and short-growing, cool-season grasses and legumes are 4-6 inches tall. At these heights, pasture quality is high, forage is easy to eat, and recovery after the last graze has been sufficient. Move the cattle out when pasture is grazed to 3 inches. Rotational grazing and strip grazing help ensure maximum productivity of cows and pastures.
  2. Make a gradual change to heavy pasture over 1 - 3 weeks by limiting grazing time initially and gradually reducing intake of stored forage.
  3. Lower grain levels slowly (4 lbs/week) to prevent sudden drops in production.
  4. Feed grain at levels indicated by pasture analysis and ration formulation.
  5. Protein levels in an accompanying TMR or grain mix can be dropped because of the high protein content in lush pasture.
  6. Pasture intake will be 2.0 - 2.7% of body weight depending on concentrate intake. Dry matter intake of stored forages should be subtracted from this value.
  7. Feed 5-8 lbs stored forage per day to maintain butterfat.
  8. Remove from pasture at least two hours prior to milking if off flavors are a problem.
  9. If a TMR is fed with pasture, reduce TMR feeding to maintain a 5% refusal.
  10. As intake of a TMR and grain mix is reduced, remember to increase levels of minerals and vitamins accordingly.
  11. Provide shade and ample quantities of good water on pasture.
Manitoba dairy producers wishing to learn more about pasture management should contact MAFRD for A Guide to Management Intensive Grazing.
 
Source: Nutrition Update Volume 9 No.1, May 1998