eOrganic author:
Mike Gamroth, Oregon State University
The amount of Net Energy for Lactation (NEL) required for grazing activity is listed below in Table 1. Grazing activity is a function of body weight (BW), distance walked between pasture and parlor, and topography of the pasture. The equations used to calculate these values assume that dry matter intake (DMI) is 'normal' for the given body weight and that pasture is 60% of the total DMI.
| Total Distance Parlor to Paddock (miles/day) | Body Weight =1000 | Body Weight = 1400 | ||
|---|---|---|---|---|
| Flat | Hilly | Flat | Hilly | |
| 0.25 | 0.63 | 3.33 | 0.88 | 4.66 |
| 0.50 | 0.71 | 3.41 | 0.99 | 4.77 |
| 0.75 | 0.79 | 3.49 | 1.11 | 4.89 |
| 1.00 | 0.88 | 3.58 | 1.23 | 5.01 |
| 1.25 | 0.96 | 3.66 | 1.34 | 5.12 |
| 1.50 | 1.04 | 3.74 | 1.46 | 5.24 |
| 1.75 | 1.12 | 3.82 | 1.57 | 5.35 |
| 2.00 | 1.21 | 3.91 | 1.69 | 5.47 |
Approximately 0.31 Mcal NEL is required for production of each pound of 3.5% milk (or 0.33 Mcal for 4.0% milk). Therefore, as an example, if we assume that DMI and nutrient intake remain the same (it may or may not), a 1000 pound cow that has to walk on flat ground for an extra two miles each day may lose 2–4 lbs/day in milk production (1.21/0.31).
A 1400 pound cow walking on hilly ground an extra two miles per day may lose more than ten pounds per day in milk production (5.47/ 0.31 = 17.6 lb of milk lost) if additional energy (or DMI) does not make up the difference for this increased activity.
References and Citations
- National Research Council. 2001. Nutrient requirements of dairy cattle. Seventh revised edition. National Academy Press, Washington, DC. (Available online at: http://www.nap.edu/catalog.php?record_id=9825) (verified 18 March 2010).
