Ahh, spring. The time when the grass starts popping up, the leaves begin to emerge on the trees. Naturally this time of year is tough to resist the urge to turn cows out onto pasture, particularly if you're running low on feed. But is it really a good time to turn cows out just by the fact that the pastures are starting to turn green?
The short of the answer is that no, it's not.
That first blade of grass that begins to emerge from winter dormancy is a result of the remaining energy stores from over the winter months. That first leaf that shows up means that the plant from last year has spent most of its energy stores. Grazing that first leaf now could be very detrimental to that plant, and thus the entire pasture.
The first leaf is the one that begins photosynthesis. Photosynthesis is how plants get their energy, and it will be how that grass plant will slowly start to refill their root energy reserves, but not before they use that energy to put up even more leaves. More leaves mean more photosynthesis which means more energy captured for more growth.
Allowing animals to graze those first emerging leaves sets those plants back far enough that they must draw from more energy reserves that may very well be mostly depleted. Roots are not likely to develop as big and robust as they should, instead becoming smaller and weaker as new leaves are grown.
Shallow and weak roots predispose plants to become much more sensitive to dry conditions to where they are more likely to shut down and go into dormancy much earlier in the year. They are unable to find more water and nutrients than what they can already reach with their roots, thus become stressed. This has an impact on their health in a way that makes them more prone to insect pests and disease.
Regrowth therefore, will be slowed significantly, such that there may be less pasture forage available for the rest of the year, and such that the amount of time available on pasture is going to be significantly reduced. Typically, for every day early that animals are turned out to pasture is three days sacrificed for late summer or fall grazing.
So, when is the best time to turn cows out to pasture? My piece of advice is to go by the number of leaves that are on most grass plants in the pasture, not the height of the sward. I know a lot of other publications tell folks to start grazing at anywhere from 6 inches to 10 inches tall, but they tend to ignore the different characteristics that various grass species have that don't follow that kind of textbook advice. For example, Smooth Bromegrass (Bromus inermis) grows taller than Western Wheatgrass (Pascopyrum smithii). By the time that smooth brome is "ready to graze" at, say 8 inches tall, western wheatgrass is already putting up a seed-head, and well past that "ready to graze" time.
Therefore, the best time to begin grazing in the spring is when plants have reached the 3 to 3.5 leaf stage.
The actual amount of time it takes for plants to get to that stage depends on previous management, moisture conditions, particular species being grazed, and other factors. Usually if spring is quite dry, or if plants are coming from a previous year where they were stressed from overgrazing, drought conditions, and/or insects, it will take longer than what may be considered "normal" for the area. As a result, grazing may need to be deferred at least 2 to 4 weeks later than normal.
Plants tend to shut down early when stressed, and therefore need to draw on root reserves for a longer period of time. Plants not given adequate biological time to recover will decline in health and productivity, which eventually may lead to death. This loss may not be noticeable during the time where drought or overgrazing is clearly evident, but it may certainly show up come the following spring.
This is why giving those plants the rest they need to recover is so crucial. Time for recovery really is the cheapest rejuvenation strategy in a person's pasture toolkit, and should be used on a regular basis.
That new spring regrowth, though, is going to have to be managed to guarantee a productive stand throughout the year. Plants in the spring will need to be grazed lightly where only one-third to one-quarter of the plants--basically a single bite--is taken. This can only achieved when you mob graze your animals--some may call it "rotational grazing"--not with continuous grazing systems. Taking that one bite then quickly moving the animals from one paddock to another will leave plenty of green "solar panel" behind for a fast recovery period.
Grazing too heavily--such as taking more than half--means longer times for plants to recover. Grazing heavily all the time plays a heavy toll on the year's forage yield and productivity. Basically, the harder you graze the less grass will come back.
How long to let the plants rest after the first bout of grazing really does depend on factors such as moisture and how much was removed. Typically a rest period of 21 to 30 days is sufficient, but expect longer if too much was taken or the rains haven't arrived yet.
A good rule of thumb for grazing is to graze fast when the plants is growing fast, and graze slow when plants are growing slow. Fast-growing plants need shorter rest periods than slow-growing grass.
If you're short on feed and have no choice but to turn cows out to pasture, consider supplementing with grain and/or pellets or cubes to give the cows an additional feed source other than just the pasture plants, and alleviates a bit of the grazing pressure. Creep feeding calves is also recommended if pastures are short, as doing so takes the pressure off the cows to meet their calves' needs when milk may be in short supply. Calves can be started on a creep ration as early as a few weeks of age. Having a sacrifice area for the animals may also be needed until pastures are ready.
All in all, grazing too early is when grasses are just starting to emerge. Waiting a bit longer can yield some good results later on. Really, if you look after the grass, the grass will look after you.
This is more of a "farmers/ranchers only" section where I share and expound on the various tips, tricks, and information on how to raise cows and cattle, from feeding and grazing to breeding, to handling and keeping them healthy. This is really for anyone who wants to raise cows, or is already doing so!
Range Nerd, Forage & Grazing Fanatic and a Bovine Enthusiast. A love for farming, and for the soil.