Grazing Bites: Questioning Grazing Efficiencies

By Victor Shelton

NRCS State Agronomist/Grazing Specialist

I’m a bit late getting this out this month and it has nothing to do with avoiding April fool’s Day; I’ve actually been under the weather. Amongst other things, that has made me stop and think a little about time, specifically the value of time. When I was young, time seemed endless and even summers seemed long. As we age, we start wondering not only what happened to the month that we are in, but what happened to the last year! There are certainly moments in time that I would give any amount of money to have back; those are high value moments. It is easy to find ourselves trapped in a set of habits or in a redundant pattern that holds us hostage and eats away our time; those are very low value. Every time I find myself doing something with no rhyme or reason. I often ask myself “Why am I doing this?” This is not true about time spent on grazing management.

There are certainly times when it would be much easier to just leave all the gates open and let the livestock manage themselves. Obviously, there must be some merit in this type of management, or lack of, because it is still pretty common. This is especially true in the spring. For those whose primary focus is planting corn and beans, pasture management is usually not a high priority. Equipment, field preparation and planting is the top priority; the cows will be fine until planting is done, until side dressing is done, until first cutting of hay is done, etc. Unfortunately, by the time most of those producers have completed that work, they are usually short on forages. Hay or other fed feeds now take the place of management or time not expended earlier.

I still often question grazing efficiencies. Certainly not all of the forage that is produced will make it into the animal and likewise, not all of the potential growth is always lost or achieved. Grazing efficiencies have a lot to do with time. Time to grow, time to graze and time to rest. The real trick is to achieve the highest efficiency of the whole.

If you let a field grow to its maximum and then harvest it mechanically, you are still missing out on some potential regrowth that did not occur during that timeframe. You then have to account for any loss of leaf and stubble left behind. This is why hay harvest is considered about seventy percent efficient.

If you turn the cows out and let them harvest the field all season long and they are still grazing something green, quite often close to the ground especially with higher stocking rates, you might think you haven’t wasted a thing. In reality, because you have restricted photosynthesis and leaf area, you have restricted production and most likely intake of the animal. This is all compounded if it also turns dry.

To really maximize both production and efficiency, we need to manage time. We’ve talked about the three stages of grass before: the immature stage, where it is washy; the growth stage, where it is nutritionally rich and high in energy; and the mature stage. In an ideal world of forage, we would keep all of the pastures or paddocks in stage two all the time. To save some time, I’ll quickly say that that is pretty much impossible and not always ideal.

Forages usually don’t want to cooperate. They want to complete their life cycle which includes producing seed as part of a survival mechanism. Each has a typical growth curve and towards the end of the biggest growth period, seed is usually produced. You can slow this down or slightly flatten that growth curve by forcing the plant to regrow by removing sufficient material. This forces the plant to rebuild reserves.

Take away too much and we stunt regrowth. Don’t remove enough and let some mature, then quality is reduced.

There are a lot of variables that play into all of this: stocking rate, fertility, soils, rainfall, forages, and weather patterns. Every season is slightly different. I’ve wished at times that I had taken clippings during the same time-frame and under the same conditions for several years to compare differences. You would think they would be very similar, but I’ve found them to vary quite a bit. Differences in growing degree days, rainfall, and fertility are enough to throw wrenches in the works of true comparability.

Mercy, what kind of tangent have I gone down? I believe we were discussing grazing efficiencies. We actually harvest the most forage over the entire growing season by maintaining as much forage as possible in stage two. That is when we maximize intake of the animal, enabling them to get a full bite each time, maximize the nutritional value of that forage, and if we adhere to good stop grazing heights, we will prolong that good growth and possibly even increase new tillering, as long as the weather, moisture, and fertility are present to support it.

There are certainly reasons to graze tighter every once in a while as there are reasons to defer grazing long periods. Those could include to establish new legumes, to stockpile forage in late summer or fall for later use, or build a large amount of carbon to be utilized for building soil health. All are good justifications for the planned goal, but all can also reduce overall yearly production.

We started this whole discussion with the topic of time, or more specifically the value of it. I continue to test the grazing efficiency percentages. Even with all the variables that influence them, I find them hard to disprove. So, what is the value of time managing pasture? The grazing efficiency of the pasture increases with the increase of time in management. The more often animals are moved and pastures rested and maintained where grazing is maximized in the most ideal stage of growth, the higher the efficiency. You could essentially increase the amount harvested over 200% by adding management to a continuously grazed pasture. That is measurable quantity that you don’t have to buy.

At the end of my day, before I try and get some sleep, I hope that the time I spent was either educational, memorable, or rewarding to myself or someone else. Once it is gone, it is gone. Learn from others as much as you can, so we don’t have to keep resolving the same problems over and over again. I think it was Will Rogers that said, “There are three types of people: the ones that learn by reading; the few who learn by observation; and the rest that have to pee on the electric fence and find out for themselves.”

Source:osu.edu