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Management-Intensive Grazing: Forage Allotment

Daily Forage Requirement

On any given day, grazing animals will consume a certain amount of dry matter (DM). The easiest way to visualize and calculate this amount is as a percentage of their body weight. Of course, this percentage is affected by many factors (e.g., production level, animal genetics, rate of supplementation, animal health, forage availability, forage quality, etc.).
Though a more precise estimate of daily DM intake can be found in the National Research Council's Nutrient Requirement series for individual animal species (see Supplementing the Grazing Animal page), the data in Table 1 can help you approximate the amount of forage that an animal will consume on a daily basis.

Table 1. Approximate range in dry matter (DM) intake of forages for selected animal classes.

  Animal Class
Forage Intake Range
   
(DM) as a % of b.w.)
  Dairy Cow
2.0 - 4.0
  Dairy Heifer
2.2 - 2.8
  Bull
1.5 - 1.9
  Beef, cow (dry)
1.7 - 2.0
  Beef, cow (late gest.)
1.8 - 2.1
  Beef cow (early lact.)
1.9 - 2.4
  Beef, stocker (steer)
2.4 - 3.2
  Beef, stocker (heifer)
2.2 - 2.6
  Beef, finishing
2.3 - 2.5
  Beef, replacement heifers
2.0 - 2.4
  Sheep, ewes (dry)
1.5 - 2.0
  Sheep, ewes (late gest.)
2.2 - 3.2
  Sheep, ewes (early lact.)
3.0 - 4.8
  Horse, Mature (maint.)
1.0 - 2.0
  Horse, Mature (late gest.)
1.0 - 2.0
  Horse, Mature (early lact.)
1.3 - 2.6
  Horse, Weanling (< 600 lbs.)
2.3 - 2.8
  Horse, Yearling (600-1000 lbs.)
2.0 - 2.3
  Goat, nanny (dry)
1.5 - 2.0
  Goat, nanny (late gest.)
2.2 - 3.2
  Goat, nanny (early lact.)
2.8 - 4.8


So, for example, a 600 lb stocker will eat approximately 19.2 lbs of DM per day (600 x 3.2% of b.w. = 19.2 lbs). Does this mean that one only needs to ration out 19.2 lbs of pasture per 600 lb stocker? Unfortunately, it is not that easy. Once this estimate of forage intake is calculated, the actual daily forage allotment must take into account the relative efficiency of the grazing system (see Grazing Efficiency page).

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