Grazing cell design: Fixed vs flexible design

When it comes to making fence and water developments, we have two basic approaches to setting up a grazing cell. I like to refer to them as fixed or flexible designs. A fixed design is built using permanent fence and water installations to create the grazing cell while a flexible design relies on movable fence and water for paddock subdivisions within a framework of permanent fence and water installation. Then, there is a wide range of combinations of the two.

Cows graze in a green pasture behind a barbed-wire fence.

Deciding which approach is right for your operation depends on a number of factors. Flexible designs allow much more fine tuning of the pasture-animal balance so if you need tight management control, a flexible design might be right up your alley. Fixed designs require less daily labor so, if you’re short on time, a fixed design might suit you better. Any kind of fence or water development costs money. Fixed designs are better suited for large operations where paddocks are large enough that development costs can be spread over many acres. If you’re short on capital, starting out with a flexible design might be more affordable. There are advantages and disadvantages to each approach.

In a fixed design, all subdivisions are made with permanent fence. My definition of a permanent fence for any class of cattle is a single strand of electrified 12.5 ga hi tensile wire on solid corners with line posts the wildlife don’t knock the wire off. In very dry conditions, a two-wire fence may be necessary with one strand hot and one strand grounded. For sheep or goats, three strand fences are most commonly used, although some people do alright with just two wires.

Watering points in fixed designs are commonly either the water source itself, such as stream, spring development or pond, or has water delivered to a tank via buried pipelines. Tanks are typically large, often containing a full day’s water supply or more. Pipe flow can be pretty slow and the water supply will still be adequate. The negative effect is watering activities always occur at the same locations in fixed designs.

Fixed designs have a number of advantages, particularly on large operations. Because the expensive part of fencing is in energizers, ends and corners, and gates, the more acres you can spread those costs over, the lower the cost per acre. Ultimately it is animal product sold per acre that pays the bills, so lower cost per acre yields higher gross margin per acre. Picture this. It takes the same number of end assemblies and gates to create ten paddocks on 20 acres as it does to make ten paddocks on 200 acres. However, cost per acre is going to be much lower on the 200 acres compared to the 20.

On most days, the labor requirement on a fixed design consists of opening the gate and letting the stock to the next paddock. Use good quality material for the fence and water designs in the first place, install it properly, and maintenance on the grazing design is pretty minimal. The initial investment may be higher up front, but operating costs on a fixed design can be quite low.

The main disadvantage to fixed designs is that management flexibility is limited. As growth rate changes through the season, you can adjust the length of the grazing period but you cannot change the size of the pasture allocation without resorting to temporary fencing. If paddocks are less than

ten acres, efficiency of any mechanical operation is also diminished. On smaller operations, the cost per acre can be substantial because of limited number of acres over which to spread costs.

Flexible designs require more management and more daily labor to use effectively, but offer several important advantages. The primary advantage is increased management flexibility from both grazing and mechanical harvest perspective. The ability to flex paddock size and forage allocation as conditions change offers greater management control.

Labor requirements in a well-designed flexible design can be fairly minimal. Getting an easy working design requires setting up the permanent framework to enhance your time efficiency. Laying out the grazing design as a series of near-parallel grazing corridors is the starting point. I generally recommend keeping corridor width to less than 1000 feet to accommodate easy use of fence reels and step-in posts.

My personal preference is to space permanent fences at 660 feet with a water line along alternating fence lines. Why 660 feet? Because each 66-ft allocation equals one acre. Install your permanent line posts at 66-ft spacing and you have a built in paddock measuring device. It makes it very easy to keep track of what you are allocating and give instructions to kids and hired help doing chores for you. Most layouts do not lend themselves to such an ideal layout. Generally we try to keep the grazing corridors in the 500 to 1000 ft range. This is a reasonable amount of movable fence to work with each day. It would typically take me 15 to 25 minutes to take up one fence and set up another with these distances.

Even though the daily labor requirement for operating a flexible design is greater than labor in a fixed design, the time needed to move fence and water is pretty minimal if you are using the right equipment and have set the design up as described above. Over the last 20 years I have timed myself and other people working with portable fence and water designs. Day in and day out, it takes me less than 15 minutes to take down a 660-foot section of polywire on step-in posts and reset it for the next grazing strip. Using a 50-gal plastic tank and quick coupler valves requires about five minutes to move. In most situations it takes longer to get from the house to the paddock than to make the paddock shift.

During one five-year research project at FSRC, we had eight herds rotating in flexible designs. I could typically go out and move all eight herds in about two hours including walking from pasture to pasture. The lengths of fence ranged from 330 to 600 feet and the water tanks were 25 gallon plastic tubs. Set it up right, use the right equipment, and it doesn’t take much time at all.

A water line along each alternating fence allows two corridors to be watered from each line. The spacing of the water outlets depends on expected herd size and the needed allocation area. The key factor to making portable water tanks work is high recharge rate in the delivery design. Whereas water tanks in fixed designs can be large and rely on slower refill rates, flexible designs must be installed with high flow capacity to get rapid refill so that stock can never drain the tank. Some people think this means high pump pressure but it is actually much more related to pipe size. Just increasing pipe size from 1″ to 1.25″ increases water flow by more than 50%.

Even if you install appropriate sized pipe for the main line, water flow can be restricted by using a small diameter delivery hose or a tank valve that restricts water flow excessively. Hydrants and quick coupler valves are the first point of restriction from the pipeline. Use larger diameter hydrants and valves wherever possible. If you put in a one inch hydrant, don’t lose that advantage by running a half-inch hose to the tank, particularly if using hose lengths greater the 20 to 30 feet. Larger diameter hoses cost more but deliver a lot more water. A one inch hose delivers four times as much water as a half-inch hose.

So how do you decide whether to use a fixed or flexible approach? As a general guideline, I suggest flexible if your operation is less than 160 acres. If you are managing over 1000 acres in a single grazing design, fixed may be a better option. In between those two benchmarks, a combination design is likely to work best. Having said that, I know operations in excess of 1000 acres that are almost entirely flexible and I know 40 acre farms set up with fixed facilities.

Dennis McDonald, an early pioneer of controlled grazing in north Missouri, originally set up all of his farms as fixed designs. Dennis runs several hundred head of cattle on over a thousand acres. After 10 to 12 years of grazing successfully in those fixed designs, he converted all of his farms to flexible designs because he saw even more benefit to tighter control and found the flexible design easier to manage. Dennis is a full-time farmer who markets his labor through cattle production. The additional time he spends managing in the flexible mode has increased his output per acre so it is time well spent.

Jim Twesten is a custom stocker grazier in who works off the farm and has very limited daylight hours on his home place. Jim typically runs around 300 head of yearlings on his 320-acre home unit in a fixed design consisting of about 20 paddocks with permanent water tanks. Because time is his most precious commodity, Jim prefers to minimize his daily labor at home and uses a well designed fixed design.

Eric Bright operates a 60-cow pasture-based dairy and runs a very intensive flexible design to maximize grazing intake of his dairy cows. Moving fence and water every 12 hours requires using the right tools to do it efficiently. Eric uses some annual crops such as ryegrass and brown midrib sorghum so the flexible setup allows him to no-till drill the annual crops in long corridors rather than in small blocks.

Three graziers with three different sets of goals and you get three different designs. Your design needs to be a reflection of your goals.

This article is a result of soil health and grazing workshops KAWS held in 2018 across the state. Funding for the workshops was provided by the North Central Extension Risk Management Education Center and the USDA National Institute of Food and Agriculture. Project partners include the Kansas Alliance for Wetlands and Streams, NRCS-Kansas, Kansas Water Office, K-State University, Kansas SARE, No Till on the Plains, Kansas Dept. of Health and Environment, nine Watershed Restoration and Protection Strategy groups, Kansas Grazing Land Coalition and Friends of the Kaw.