Back in the day, when my dad had beef cows and calves on our farm, he would turn them out every spring to the pasture on May 1. It was the common and usual practice, 30 years ago, to use the calendar to determine when to turn animals out on pasture. The question still remains: When is the best time to start grazing?

The recommendation to graze a field is now given based on the plant height. Depending on factors such as forage species and the species of animal doing the grazing, the general recommendation is to turn out when the forage is six to 10 inches tall.

If, however, you do wait until the forage is this tall, it will be very difficult to keep ahead of the spring flush. If the plant is not harvested by the animals, it will go into the reproductive stage and growth will slow way down. A grazer never wants to see a seed head or a flower in his pasture.

Cool season grasses can break dormancy when the temperatures are 40 degrees Fahrenheit. The first growth is fueled by energy reserves stored in the roots and the crowns. This first green up growth is very slow. It is not a good idea to allow animals to graze during this period. If you do, you risk reducing yields or even killing the grass. If reserves are low in the plant because of fall weather, they may be used up by fueling the first two to three days of growth. If the plants are grazed during this period, it may mean no growth from the plant.

Once the plant has enough leaf to produce photosynthesis, growth really takes off. This is the second stage of growth, many times called the spring flush. During spring flush, cool season grasses produce 40 to 60 percent of their annual growth. This occurs in April, May and early June. If the grazer waits until the general recommendation and doesn’t begin to graze until the grass is six to 10 inches tall, the quality of the forage will decline rapidly as it approaches the reproductive stage. It is also difficult to get the staggered re-growth needed in the lots to make the rotations go smoothly. The first grazing needs to begin earlier.

The first grazing of a lot should be light. Begin when the forage is about three inches tall. Take the animals through each lot very quickly. Never graze closer then two inches. You do not want to remove half of the leaf surface on this rotation. Remember you need these leaves to fuel the plant growth. This means the animals may be moved to a different lot each day during this time.

There is one exception to this plan and that is if the fields are too wet to graze with out mudding up the lot. If the lot is not well drained, then we would recommend you go back to the general six inch height recommendation. The extra growth will help support the animals. This grass should not be grazed to less than three inches before the animals are moved.

This farm news was published in the March 15, 2006 issue of Farm World.