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It’s all about the regrowth

Woody Lane, Ph.D. for Progressive Forage Published on 27 April 2018
cattle grazing

When I teach my course on pasture management to livestock producers and get to the topic of grazing, the ranchers ask very practical questions, such as: When should I open the gate to let the animals into a field?

When should I move the animals off? How long is too long?

These questions and their permutations may be endless, but the principles they invoke are not. So here, briefly, I’ll cover one critical principle of good grazing.

(Important disclaimer: Here, I’m talking about improved pastures or at least improvable pastures. Grazing livestock in open range country is a different universe entirely.)

Critical principle: The 5-Day Rule

Have you ever carefully watched grass grow? Really watched it? Let’s say you have a pasture with good fertility and sufficient water, containing forage that has excellent genetics for rapid recovery and high growth rate. After animals graze this forage (or after equipment cuts it), how many days pass before you can see the little bright green shoots of regrowth? Hmmm. Well, next time look carefully. In my fields, I’ve seen that bright young regrowth within four or five days.

Now let’s think about this: If a sheep or goat or cow is still wandering around that field during this period looking for something to eat, and it comes across these new, bright green shoots, what will it graze? Will our animal choose to avoid this new vegetation and instead munch on older grass, or will it happily graze our new shoots and look for more? The answer is obvious.

But let’s pursue this concept a little further. When our grazing animals preferentially select these new shoots, they effectively put selection pressure against the very plants that we want in our pasture (i.e., the valuable forage plants that show new growth and recover quickly after defoliation). In addition, the new palatable regrowth may come from plant reserves, and this type of grazing management systematically lets our animals destroy those reserves before plants can fully recover.

And if we allow our animals to do this for weeks or months then, over time, the only forages that will thrive in those fields will be plants with slower regrowth and lower palatability, including awful weeds like thistles and toxic plants that are really less attractive to our livestock.

Hence, my 5-Day Rule: Do not keep animals in a paddock for more than five days. Fewer days is usually better, but that choice depends on the management details in each farm or ranch. Dairy farmers, for example, move animals twice each day anyway, so for them, a 12-hour move makes sense. Graziers with other species of livestock may move animals every one to four days based on their specific production system and their strategies for managing time and labor, but never more than five days.

In other words, we should always protect the forage regrowth in a pasture. I repeat: We protect the regrowth. In fact, as good graziers, we should become fanatical about protecting the regrowth. A grazing period of five days or less gives us a management tool to do this.

The 5-Day Rule implies lots of things, especially about some traditional approaches to grazing. First, look at any classic textbook on forages, such as the books assigned to university students for their agronomy courses. Those textbooks list all types of grazing techniques that are each carefully named and defined (which students must memorize for their exams), like “creep grazing,” and “forward creep grazing,” and “first-and-second grazing,” and “put-and-take grazing,” and “multispecies grazing,” and others.

But in light of our 5-Day Rule, all these grazing techniques and memorized jargon comes down to this: Animals should be off the field within five days. Period. It’s all about regrowth. No matter which livestock species we use, or how we select their subgroups, or how skillfully we design the sequences for one subgroup to follow another, the basic axiom is that everyone must be off that field before the plants begin any significant regrowth.

And when we keep this principle in mind, all the various grazing techniques actually become variations of the same theme. Sure, we can graze the lighter animals first and then follow up with heavy breeding stock. Or we can design a clever creep-grazing system, which allows very young stock to graze ahead of their mothers. Or we can top off a pasture with one mob and then “clean it up” with a follow-up mob.

Even the popular concept of multispecies grazing falls neatly under the same principle – start with sheep, follow with cattle. Or start with cattle, follow with chickens. Or start with goats and follow with sheep. Whatever. Just get the last group of animals off the field within five days. The rest are just details and preferences.

Set stocking

Which brings us to the important grazing concept of “set stocking.” Most folks think they know about set stocking – that it’s a type of grazing management system in which animals are left in a field for a hundred years, and they demolish all the forage in that field. While that scenario might be true, it’s not quite the full story. Viewed in the light of our 5-Day Rule, the concept of set stocking takes on a whole new and insidious meaning.

Set stocking really means that animals will consume young regrowth. Which means that set stocking isn’t only defined by weeks or months on the same field, but rather it can be defined by days – a few extra days that allow animals the opportunity to eat our field’s most valuable forage, its regrowth.

This means that set stocking can actually occur on a fertile pasture in only seven days, which implies that forages can be damaged by leaving livestock on them a few extra days, not just the classic weeks or months that most people think.

“But,” you argue, “my field is too big. It takes my flock (herd, mob, pod, etc.) at least 14 days to graze all the forage in that field.”

Actually, there is a straightforward answer to this problem: electric fencing. Set a temporary electric fence across that field to reduce its size. Aim for a size that allows the animals to consume the feed in only three to five days.

Where to put that fence? Well, first estimate the available amount of feed in the entire field; then estimate the amount of feed needed by the livestock per day. A rule of thumb is to use a dry matter disappearance of 4 to 5 percent of bodyweight per day. Then position the temporary fence to give the animals X days of feed, where X is a number of five or less.

In other words, you allocate feed and then set the fence so your animals will harvest that amount of feed in a few days. If you estimate wrongly, you’ll either run out of feed early or have too much feed remaining after five days. In either case, you will have learned about feed allocation, and you will set the fence better next time. Not bad – a win-win situation. And eventually your forages will thank you for this, because you will have protected the regrowth.  end mark

PHOTO: We punish the regrowth of desirable forage when we leave livestock in pastures longer than five days, no matter what grazing technique is used. Photo by Lynn Jaynes.

Woody Lane is a certified forage and grassland professional with AFGC and teaches forage/grazing and nutrition courses in Oregon, with an affiliate appointment with the crop and soil science department at Oregon State. His book, From The Feed Trough: Essays and Insights on Livestock Nutrition in a Complex World, is available through Woody Lane.

Woody Lane, Ph.D.
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