A grazing situation: Quality vs. quantity

This spring has been unique. In my area, April forage growth was slow with many producers staying ahead of the growth to the point they were concerned with overgrazing.

Then the rains came. Within days everyone had a burst of growth.

Because of April’s growing conditions many paddocks were not staggered or staged at different heights. It left producers with all of their acres exploding at the same time and going to head.

“What is more important, quality or quantity?” was one question asked as a grazier and I were walking fields and discussing options for all of the paddocks that could not be grazed before they went to seed.

Deserves good answer. I answered quickly then spent some time explaining my answer. That is a valid question and really deserves more than a one word answer.

First let’s look at it from the plant growth side. Forages break dormancy in the spring and start to grow leaves. This growth is fueled by reserves stored in the roots or crowns of the plant. Usually this growth is slow and has been referred to as stage one.

Once enough leaf area is produced the plant really takes off. This is the second stage.

Growth is now fueled by energy produced from photosynthesis with some replacing what was used earlier from the reserves. At the end of stage two grass stems start to elongate and seed heads start to emerge.

By stage three the plant is in reproductive mode. Seed heads are flowering and legumes are in bloom. Dry matter production at this point drops off.

The lower leaves are shaded and dying. The focus of the plant is producing seeds not leaves.

During growth. What about forage quality during its growth? Forage quality starts high and steadily declines as the plant moves through the different stages.

This is true with any of the measures people would look at for quality indicators, percent crude protein, total digestible nutrients, percent minerals, or percent leaves.

The percentage of stems and lignin increase as the plant grows which also detracts from the quality of the forage.

To maximize quality we would graze during stage one. Yields will be the lowest and regrowth will be slow.

And one caution, constantly forcing the plant to grow from its root reserves will eventually kill it.

To harvest the most yield, pounds of dry matter per acre, we would graze in stage three. Besides total tonnage another advantage to this is that we also maximize the reserves stored in the roots.

The quality may not be good enough for most of the classes of livestock, limiting their performance.

Keep it here. Ideally graziers would like to keep the forage in stage two by grazing before the end of this stage. Livestock should be removed before enough leaves are grazed forcing the plant into stage one.

If this could be done then regrowth would be rapid, quality would fit most livestock’s needs, and yields would be respectable.

Depending on the type of forage, grazing in stage two would typically start when the forage is less than 10 inches high and stop with a residual of 2-3 inches.

Harvest tools. Another important part of the quality verses quantity question is what we are using to harvest the forage.

Ruminants on pasture will consume 2-4 percent of their body weight in dry matter per day. They do not spend all day grazing.

Depending on their production stage they will graze 5-12 hours in a 24-hour period. So they have a limited amount of time to find and graze all of the feed they need for that day.

If we limit their intake we will also limit their production.

Intake. From past research we know that forage availability has an impact on the animals’ intake.

Short forage, less than 2,000 pounds of dry matter per acre, limits how much forage an animal can harvest.

Animals spend too much time searching for feed and each bite is not full. This is another reason grazing at stage one would not be the best option.

Tall forage has a higher lignin content and lower digestibility which slows the rate of passage through the animal and decreases the amount of forage they will harvest.

This is the same reason animals eat more good quality hay than poor quality hay. Poor quality hay takes longer to digest so they don’t eat as much.

That does not mean they don’t need more of it. Eating less of the poorer quality forage will limit performance. This helps rule out the third stage of growth as the best option.

From the animals’ side, the optimum grazing height is about 4-6 inches high taking off 2-3 inches before resting the pasture.

Which brings us back in stage two as the best forage growth stage to graze. That was my answer to “What is more important, quality or quantity?”

(Jeff McCutcheon is an OSU Extension, Agriculture and Natural Resources Agent in Knox County. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)

About the Author

Jeff McCutcheon is an Ohio State University Extension, Agriculture and Natural Resources Educator in Knox County. More Stories by Jeff McCutcheon

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