An explanation of rotational grazing

By Gary Sliworsky
Ag rep, Emo

What is rotational grazing? Jack Kyle, grazier specialist with Ontario Ministry of Agriculture, Food and Rural Affairs, gives his explanation:
As I talk to farmers across the province about grazing management, I have come to realize rotational grazing means different things to different people.
The dictionary definition of rotation is “to change or alternate in a particular sequence; regular variation.”
To a crop producer, rotation means a different crop or sequence of crops in a field over a number of years. But when we talk about rotation in relation to grazing, the most important factor is the state of the grass growth.
The guiding principal of rotational grazing is to give the grass crop every opportunity to grow and produce forage for the livestock. The rotation refers to the movement of the livestock from one paddock to another during the grazing season.
According to the University of Guelph and the OMAFRA Beef Cow-Calf Benchmarking Study, the biggest cost component is feed. When asked about grazing practices, more than half of the participants reported they were rotational grazing.
However, there was a big range in the results they were achieving.
The concept behind rotational grazing is to harvest the grass quickly and then give the forage time to recover and re-grow. This is accomplished by giving the livestock enough grass for the prescribed feeding period and then moving them to a new field.
The more frequent these moves, the more productive the pastures will be.
The maximum length of time in a paddock should be five days. Why five days? Grass starts to re-grow five days after it is harvested.
When does a hay field begin to green-up after being cut? There usually is new growth started in five-six days. In a pasture, this new growth is candy to the livestock and they quickly re-graze it.
This re-grazing depletes the root reserves of the plants, reducing plant vigour and subsequent growth.
An optimal rotational grazing system has the livestock moving to fresh grass every one-three days. If the grazing period is longer, there will be reduced performance by both the livestock and the grass.
Think of the pasture field as a feed bunk. Would you expect livestock to perform well if the feed bunk only was filled every five days?
Fresh feed encourages consumption, and increased consumption means increased performance.
For each group of livestock you have on pasture, there should be a minimum of 10 paddocks to give the grass an opportunity to recover from the grazing.
Twenty paddocks will go a long way to encouraging increased animal intake. Thirty paddocks will allow you to realize the full potential of both the pasture and the grazing livestock.
This may seem like a lot of paddocks, but with the use of electric fence, including some temporary or portable fence, it does not need to be insurmountable.
Cattle trained to electric fence, and accustomed to moving every one-two days to fresh grass, will meet you at the gate for their next move.
Grass growth varies during the season. Rapid growth occurs in May and June while much slower growth happens during July and August, when temperatures are higher and moisture is less available.
Pasture managers who use an effective rotational system find they have increased grass growth and carrying capacity throughout the season, and a dramatically reduced need for feeding hay.
Rotational grazing means fresh grass every one-three days and a sufficient rest period for the grass to grow to the optimum grazing height (20-40 cm).
Rotational grazing at this level will provide the most high-quality forage at the least cost.

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