Grazing Basics

The following article was presented by Sarah Flack at the February 2, 2002 VT Grass Farmers Association Grazing Conference. Reprinted by permission of the author.

Grazing management goes by a lot of different names, I refer to it as “management intensive grazing,” because it most accurately describes the method.

Management is the most important part of grazing!

In addition to lower costs of harvesting and purchasing feed, farmers find that grazing lowers costs of labor, repairs, fuel, fertilizer, veterinarian and medical costs and electric bills.Grazing can reduce wear on tractors and other equipment, and often reduces cull rates. Other advantages that farmers report include improved herd health when grazing livestock daily, less time spent spreading and handling manure, less time spent feeding animals and environmental benefits.

Some environmental benefits of good pasture management include a dramatic decrease in soil erosion potential, decreased need for fertilizer, and a reduced amount of barnyard manure run off.Converting land which is prone to erosion over to well managed pasture is a good way to reduce soil loss. Well managed grasslands can even build soils and organic matter. This can preserve fertile soils with higher organic matter content for future generations.   Good pasture management can also improve water quality for us, our livestock and aquatic life.Perennial grasses and legumes in pastures use carbon dioxide in photosynthesis, so increasing the number of acres in grassland could potentially decrease atmospheric carbon dioxide levels!

So what exactly is management intensive grazing? Pasture plants need time to rest after each grazing, giving them time to replenish carbohydrates stored in roots (by photosynthesizing). Continuously grazing animals in the same pasture does not give the plants time to recover after repeated grazing, resulting in plants that weaken, may stop growing and even die. Under management intensive grazing, livestock will be moved to a new pasture every 12 hours to 3 days. The animals may return to that paddock as soon as 14 days in early summer when the plants are growing rapidly, but it may take as long as 40 days later in the summer before the plans are fully recovered

When animals go into a paddock, they aren’t just eating...    They are trampling weeds and dead plants into the soil, which adds organic matter.They are dropping manure and urine on the pasture so the farmer doesn’t have to haul manure out of the barn and spread it with the tractor.

Permanent pastures being managed intensively provide livestock with a “salad” of many types of plants.There may be as many (or more) as 20 or 30 different species of plants in a single pasture. This biodiversity provides the grazing animals with a range of plants to eat, and means that even in a drought year or in a very wet year, something will grow.

The biodiversity of plants above ground in a pasture is reflected below the soil surface by an amazing amount of biological activity.The roots from all theses different types of grasses, legumes and other plants combine to make up one of the highest root concentrations found in any crop. In and around these roots there is a huge population of beneficial earthworms, bacteria, fungi and other organisms.

The symbiotic relationship between legumes (such as white clover) and the Rhizobia bacteria is just one example of the beneficial role of these microorganisms. This symbiotic clover/bacteria relationship makes atmospheric nitrogen available to the legume, which may later make it available to grasses and other pasture plants.   The bacteria in turn relies on the plant for nutrients and protection.

In addition to microorganisms, earthworms are an important part of the pasture ecology. Earthworms aerate the soil, help move dead plant material into the soil, and speed the break down of animal manure. Research done by Bill Murphy in Vermont found that there were between 1,109,00 and 1,776,000 earthworms per acre in well developed pastures.That adds up to between 2,318 and 3,454 pounds of earthworms per acre! When add to that the number of fungi, bacteria, nematodes, plants and other organisms, above and below the soil, you can begin to understand the incredibly complex ecology of a pasture.

Management intensive grazing can improve pasture quality and yield, and it can convert pastures which are weedy, brushy areas where animals have to search to find good quality forage into very productive pastures which can feed more animals a high quality forage, produced and harvested at a low cost. Many farmers find that as they continue to use management intensive grazing on permanent pastures on their farms, they have more and more pasture to feed their livestock!   This means that they either need to get more animals to eat the pasture, or they have to harvest more excess forage for winter feed. Some farmers stockpile excess pasture in late summer, and let the livestock graze it after the pastures are done growing for the year.This allows the animals to spend even more of the year outdoors, harvesting their own feed.

Most dairy farmers will give cows a fresh pasture after each milking.   Cows will graze each area for 8 to 10 hours, and then that area (called a paddock) will be left to regrow.   Sheep, beef or heifers may be moved as frequently as dairy cows, or they may be moved every 1 to 3 days.The animals may return to that paddock as soon as 14 days in early summer when the plants are growing rapidly, but it may take as long as 40 days later in the summer before the plans are fully recovered.   It is also important to move animals frequently, so that each paddock is not grazed for more than three consecutive days. Grazing periods of half a day to one day will result in much higher pasture quality and livestock performance.

Another important part of management intensive grazing is that when pasture growth slows down in later summer, the total number of acres needed to graze will have to be increased.If the number of grazing acres is not increased, the plants will not be getting enough rest, and dry matter intake by animals will drop, resulting in both poor animal and poor pasture performance.One of the most common mistakes in grazing is not adding additional acres in the summer!

During the grazing season, due to the high nutritional quality of pasture, the only supplemental feed that most grazing farmers provide to livestock is minerals and water. Dairy cows usually also get a relatively small amount of high energy grain such as corn meal or barley. If you do decide to provide supplemental feeds to your grazing livestock, pay attention to the nutritional quality of the pasture!Choose feeds which are lower in protein and higher in energy.   This will generally cost less money to feed, and keep the animals in better condition and health.

HOW TO ESTIMATE DRY MATTER INTAKE AND CALCULATE THE SIZE AND NUMBER OF PADDOCKS NEEDED.

HOW MUCH PASTURE (DRY MATTER) ARE THEY EATING?

Ideally, a pasture should be grazed rapidly down to 1 - 2 inches, and then permitted to grow back up to 6 to 8 inches. A good quality pasture (with high plant density) which is 6 to 8" tall has about 2400 lbs. of dry matter (D.M) per acre. If it is grazed down to a 1 to 2" height, it has about 1200 lb. D.M./acre left.This means there is 1200 lb. D.M./acre available to the grazing livestock to eat in that paddock.

The density of the plants in the pasture will have a large influence on how much dry matter there is in your pastures.If the plants are spaced far apart (low density) so that you can easily see soil between the plants, there may only be 2000 lbs. of dry matter per acre when the pasture is 6" tall (instead of 2400 lbs.).The best way to learn how to estimate dry matter is to go to some pasture walks, or host a walk on your farm.The density and quality of your pastures will increase as you practice good grazing management!

The amount of pasture D.M. an animal will eat depends on a lot of factors (lactation, growth, animal size, supplemental feed ...). Three percent of body weight in D.M. intake is a reasonable estimate for lactating cows grazing on well managed pasture. This means a 1000 lb. cow will eat 30 lb. of pasture D.M. per day.

To prevent overgrazing of plants and maximize dry matter intake, move animals frequently, so that each paddock is not grazed for more than three consecutive days. Grazing periods of 12 to 24 hours result in much higher pasture and livestock productivity.

WHAT SIZE SHOULD THE PADDOCKS BE?

Paddock size depends mostly on how many animals you have, and how long they will be in the paddock. Refer to the pasture worksheet at the back of this article.

EXAMPLE: You have 50 cows, each weighing 1000 lbs, so each cow will need an estimated 30 lbs. of pasture DM per day (3% of 1000 lbs.).   You plan on giving them a fresh paddock after each milking. You let the paddocks grow up to 6 to 8" (2600 lbs. DM/acre) before grazing, and graze them down to 1 to 2" (1200 lbs. DM/acre), so you have 1200 lb. of D.M. per acre (2600 - 1200 = 1200) for the cows to eat (this is a high quality pasture with a high plant density). The 50 cows need 1500 lb. D.M. per day (30 lbs. DM x 50 cows = 1500 lbs.).   So they need 1.25 acres each day (1500 lbs. required per acre / 1200 lbs. available per acre = 1.25 acres).   Since you will give them a paddock after each milking, you need to set up paddocks which are 0.63 acres of an acre each (1.25 / 2 = .63). An acre is 43,560 square feet, or about 210 feet on a side if it is a square.0.63 acre is 27443 square feet (43560 x .63 = 27443), which is a square that is about 165 feet on a side (the square root of 27443).

HOW MANY PADDOCKS DO I NEED?

Research done by Bill Murphy on a Fairfax Vermont (Champlain Valley) Farm on high quality pasture produced the following average regrowth periods during a 3 year period (of reasonably average rainfall).   The regrowth periods on your farm may be shorter or longer... in a dry summer, the regrowth periods may easily reach 60 days or longer!

12 to 15 days in late April to early May

18 days by May 31

24 days by July 1

30 days by August 1

36 days by September 1

42 days (and longer) by October 1

These numbers are just averages, the actual amount of time needed for complete regrowth will probably be different on your farm. However, in general the pastures grow quite quickly in spring and early summer, and more slowly as the growing season continues.

EXAMPLE: In this example, on this Fairfax farm, if there are 50 cows that need 1.25 acres per day, total acreage needed to graze in spring will be 19 acres.(1.25 x 15 days = 19 acres)When pasture growth slows down to 35 to 40 days, acreage needed will increase to 44 to 50 acres. (1.25 x 35 days = 44 acres and 1.25 x 40 = 50 acres).

If total acreage is not increased as regrowth periods increases, plants won’t get enough rest, and dry matter intake by animals will drop, resulting in poor animal and pasture performance.

For grazing planning on your farm, it is helpful to keep records of how often, and for how long your graze each paddock each year.   Then you can know how long it takes the paddocks on your farm to grow back during the grazing season.You can keep these records on a copy of your farm map, or by using a notebook or worksheet where you write down the date, where the animals grazed, and for how long.These records will allow you to know exactly what the rest periods are in your pastures.

Records of past grazing are only useful if you use them!   Walk through all your pastures at least once each week, and record how much each pasture has grown back.This way you can plan what order to graze your paddocks in.

DESIGNING PASTURE LAYOUT

One way to begin thinking about how to subdivide your farm is to use an aerial photograph or a survey map of your farm.You can use a marker to outline pastures and meadows and to draw in existing fences.Then, using the photograph (and some common sense) you can decide where to put lanes, fencing, paddocks and water.When subdividing your grazing land, here are a few things to keep in mind:

FENCING AND WATER:

Recent advances in fencing technology makes this type of grazing management much easier.You will need a good quality energizer (well grounded!), and some perimeter fencing which can conduct electricity with minimal resistance. Here in the North East you will need some type of lightning protection   Most people use some of the wide variety of portable fencing to subdivide larger areas.The type you chose will depend mostly on what type of livestock you are grazing.

Water can be provided to cows in paddocks in several ways.   Water lines can be buried, or you can just lay pipe on the ground along a fence line or a lane.Water tubs can be small and portable, or can be larger and rarely moved. It is less expensive to have a few portable tubs than a whole lot of permanent tubs.   If piping water out to pastures is not possible, water can be provided using a sap tank (or something like it) on a wagon which is parked in the pasture.Wherever the water source is, you will probably want to use a float valve to control water flow.

To start with, try to be as flexible as possible with your fence and water system. You may change your set up a few times, and you may need to have flexible paddock sizes as your herd size changes and your pasture productivity increases.

PASTURE IMPROVEMENT IDEAS