The dramatic rise in grain prices over the past six months has dairymen wondering how they can get the most bang for their buck. Producers are working closely with their nutritionists to maximize the use of home-grown forages in rations to reduce ration costs. Over the past 20 years increasing numbers of dairymen have started to intensively graze pastures to maximize pasture as a source of feed.

Pasture lands are an underutilized and under managed resource on many farms in Virginia. Rotational grazing is a management intensive system that concentrates animals within a relatively small area (paddock) for a short period of time, for example, 12 hours to foure days for dairy cattle.

A pasture may be divided into multiple paddocks. The cattle are then moved to another paddock while the other paddocks are allowed to recover and grow. Animals are moved according to a flexible schedule based on number and weight of animals, the amount of land available, quality of forages in the paddock and forage consumption.1  Continuous grazing is use of one pasture.

Stan Pace, Agronomic Crops Agent with the Mississippi State University Extension Service, explains that “Cows are selective grazers. When put in a selective forage situation, they'll overgraze some spots and undergraze others. Over time, you will have poor quality grass and less total forage production.”2

Forage utilization efficiency is the percentage of forage grazed on a pasture.  Pace declared, “Using rotational grazing can increase efficiency up to 75 percent over conventional grazing's 30—35 percent efficiency. He said moving the cattle every three or four days yields a 50—60 percent forage utilization efficiency. To increase efficiency to about 75 percent, I'd move them every day.”2 To make the best use of rationally grazed pastures and optimize animal growth rates, supplementation may be needed.

Due to a lack of rainfall in the summer months, many pastures may not grow enough forage to meet the animals’ dry matter intake levels.  Based on forage quality and quantity and desired rates of gain, many producers supplement the grazing heifers with silages, bypass protein, vitamins and minerals, and so on. The goal is to achieve 1.75 pounds rate of gain that is needed for dairy heifers to freshen at 24 months and weigh 1,250 pounds. Soil fertility plays a major role in determining the quantities of forage produced on pasture.

A current soil test takes out the guesswork and prevents the producer from under or over-applying lime and fertilizer, either of which will decrease your efficiency and profitability. Virginia Tech soil test laboratory recommendations are based on research conducted for Virginia soils and climate. The type of grazing system implemented on a farm has major implications regarding pasture fertility.

Missouri researchers estimated that grazing animals recycle 75-85 percent of forage nutrients consumed.  An even distribution of manure throughout a paddock is required for productive plant and animal growth. Intensity of grazing rotations affects the manure coverage in paddocks. In a rotational grazing system there is an even distribution of manure because the animals are forced to consume forage in the paddock before being moved to another paddock. The Missouri researchers calculated that under continuous grazing practices, 27 years would be needed to obtain one manure pile per every square yard within a pasture. Conversely, the pasture was divided into paddocks and a two day rotation was used; then two years would be needed to achieve an even distribution of manure within the paddock.4

In times of surplus forage in a pasture, the hay can be baled and sold or stored for future use. Kentucky researchers have estimated that a ton of grass hay (fescue, orchard grass) removes 12 pounds of phosphate and 50 pounds of potash from the soil.5  If these nutrients are not replaced soil reserves will be depleted over time. Consequently, there will be a reduction in crop yields.  Soil testing determines the amount of fertilizer that needs to be applied to maintain hay yields.

Cooperative extension agents can assist producers in the design of grazing systems for their farms. Numerous grazers have stated that the greatest challenge in implementing a grazing program on their farm is taking the first step which is splitting a pasture in half using temporary fence. Once they see how easy it is to move the cattle from one paddock to another, they never look back. How many times on a dairy farm do the dairy cattle harvest their forage and distribute their manure for free? In an era of high grain, fuel and fertilizer prices, grazing heifers provides producers the opportunity to reduce their operating costs in a simple user friendly management system.

1Bellows. B. 2001. Nutrient Cycling in                               
Pastures. National Sustainable Agriculture Information Service.

2Coblentz. B. 2004.  Rotational grazing benefits pastures. Mississippi Agricultural News.

3Cady, Roger A. and Gayle Willett. Case Study of Contract Raising. Presented at NARES Conference on Calves, Heifers, and Dairy Profitability: Facilities, Nutrition, and Health, January 11, 1999.

4Lory, J. and C. Roberts. 2000. Managing nutrients in pastures to improve profitability and water quality. In: G. J. Bishop-Hurley, S.A. Hamilton, and R. Kallenbach (eds.) Missouri Dairy Grazing Manual. Missouri University Extension. University of Missouri. Columbia, MO.

5Smith, R. 2008. Soil Test Should Drive Fertilizer Decisions. Hay and Forage Grower.

Source: Peter Callan, Extension Agent Farm Business Management, Culpeper County