Slowing down the rotation protects pasture yield

Co-written by James Byrne, OMAFRA Beef Cattle Specialist

Grass doesn’t just happen. Maximizing pasture yield requires management, and one of the most important decisions a manager can make is to give their grass enough time to fully recover after being grazed. Pastures have fully recovered from a grazing event when the grass plants have 3-4 new leaves. At this stage they are palatable, nutritious, and have had time to store energy in their roots and lower stems to fuel regrowth the next time they are grazed.

However, sometimes pastures do not recover from grazing as quickly as producers would like. Often this happens when there is a lack of sunlight, cold conditions or not enough rainfall. In these situations, grazing managers should look for ways to slow down their rotation, which is another way of saying that they are making the rest period for each paddock longer. But this also means how animals are fed must also change to meet their nutritional needs.

There are two primary ways producers could slow down their rotation: add acres to the grazing platform or feed supplemental forage.

Add acres to the grazing platform

Increasing the acreage being grazed enables producers to give each paddock a longer rest. Grazing a hay field is one option, particularly if the yield potential of the hay crop is low. In these situations, it may be difficult to justify the cost of running equipment across the field, even though the crop must be harvested to prevent the plants from reaching maturity. Once forages set seed, their regrowth potential is much less than if they are maintained in the vegetative growth stages. While many producers normally take a first cut and graze the regrowth, consider changing the order in which these are done to maintain yield potential and forage quality. The decision to graze a designated hayfield must account for the likely impact on future winter hay supplies of not cutting that field for hay, considering the yield potential of that hayfield balanced against the cost of providing stored forage on the existing grazing platform.

Annual crops are another way to increase the size of the grazing platform. Cereals and Italian (annual) ryegrass can be managed much like perennial grasses in a managed grazing system, although the amount of regrowth depends very much on rainfall. Warm-season grasses, like sorghum-sudangrass or millet, can also be grazed. Because sorghums, sudangrass, and their hybrids produce prussic acid when stressed, these grasses need to be strip-grazed with a back fence to prevent livestock from eating the new regrowth before it is 60 cm (24 in.) high. Forage brassicas contain lots of protein and very little fibre, so are best planted in a mixture with grasses or cereals to prevent bloat.

It must be borne in mind that the grazing of small grain cereals or warm season annuals requires planning, (as these crops must be sown and allowed a number of weeks to grow before grazing), and so are best used in situations where forage shortages are expected.

Winter wheat fields that did not overwinter well may be an option, but producers need to clear the change of use on insured acres with Agricorp before they start grazing. Carefully read the labels of any crop protection products used on the wheat to ensure the crop is safe to graze.

Often expanding the grazing platform involves using fields that do not have livestock infrastructure in place. For cattle, a semi-permanent exterior fence can be constructed from high-tensile wire and T posts, then subdivided using reels of polywire and step-in posts. For sheep, electric netting or multiple strands of polywire are options. Regardless of species, producers need to train their livestock to the electric fence before putting them onto these fields, and make sure that the fences stay hot the entire time livestock are grazing.

While water trucks are a labour-intensive option, they are often the cheapest way to bring water to livestock on fields without infrastructure. Depending on the field, it may be possible to run temporary, above-ground water lines from a well source, or pump from a body of water. Each situation is unique, so producers must cost out the options available to them.

Feed supplemental forage

It may seem counter-intuitive to protect forage inventories by feeding stored forage on pasture. But if the goal is to maximize the amount of forage grown on the farm, sometimes this is necessary to prevent overgrazing, protect pasture yield and to provide livestock with enough feed to meet their nutritional requirements. The trick to making this work is to be proactive about feeding forage and use it as a tool to slow down the rotation. Waiting until the pasture has run out of grass results in feeding more stored forage overall.

The amount of stored forage that needs to be fed depends upon the daily feed requirements of the livestock and how quickly your pastures are growing. Pasture growth rate will determine how long you need to feed and consequently the total amount you require. 

In the case of beef cattle, mature beef cows will consume approximately 2% of their bodyweight in DM every day, whereas beef cattle under 2 years of age consume approximately 2.5% of their bodyweight in DM every day. Therefore, it’s important to have a good estimation of the bodyweights of the animals on your farm to determine your daily requirements.

Where feeding supplemental forage is a short-term solution to a short-term problem, the impact on livestock should be minimal and no additional feed, apart from the supplemental forage, will be required. But, if the lack of available pasture is a more long-term problem, place thinner animals and cows with very young calves into a separate group and provide some concentrate feed in addition to supplementary forage.

To maintain performance on older calves that are closer to their sale date considering providing an area separate from the cows where these calves can access some concentrate feed. This will have the duel effect of both maintaining animal performance and reducing forage demand.  

Avoid the temptation to feed old musty forage. This will create more problems than it solves. In addition, animals should have access to both salt and mineral to maintain good animal health.

Slowing down the grazing rotation provides a longer rest period for pastures. Achieving this can be done by increasing the number of acres grazed, feeding supplemental forage on pasture, or a combination of the two. It is never too late to start rotational grazing, and the grass will be more productive for having a rest.