# Energy Requirements of Grazing Activity

Organic Agriculture March 19, 2010

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.

Table 1. Estimated NEL requirements (Mcal/day) associated with grazing flat or hilly ground for an average Jersey cow (1000 lbs) and an average Holstein cow (1400 lbs). Note: High-quality pastures (cool-season grasses or legumes) typically contain 0.69–0.72 Mcal/lb of DM. Adapted from National Research Council (2001).
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).

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.