June 20, 2007 | By: Laura Skillman
PRINCETON, Ky.

In a year of reduced hay and pasture yields because of a late spring freeze coupled with the current dry conditions, pasture management is even more crucial than usual. Rotational grazing can play a big part in getting the most out of forages in these lean times as well as the good times.

“In a dry year like this, it gives the most efficient utilization of the grass, and with the dry weather and reduced growth, the better the utilization, the longer the cattle can stay on pasture,” said Ray Smith, forage specialist with the University of Kentucky College of Agriculture. 

Research has shown that rotationally grazed pastures maintain productivity longer into a drought than those that are continuously grazed. Yet, in any year, there are several key advantages to rotational grazing. The primary advantage is that it gives the producer management over his pastures. He’s telling the cattle what to graze rather than allowing them to graze whatever they want, which usually results in over grazing the desirable grasses. Given the opportunity, cattle often graze those out and leave the undesirable or lower quality grasses, he said. Rotational grazing also gives the farmer an opportunity to take a field or two and cut them for hay if there’s excess growth.

“By rotational grazing, there’s a lot less chance of waste from them trampling feed, and you can make them graze it down to the recommended height,” he said. “We recommend cool season grasses be grazed down to a height of three to four inches.” 

One key advantage that particularly shows in a drought is the plant has a rest period to grow back after a grazing period. The rest periods allow for new top growth, but more importantly, it also allows the root system to grow. In cool season grasses, the growth of the roots shuts down for a period of about two weeks after grazing. By allowing the field to rest for three to four weeks, or longer in dry weather, the plant has the ability to increase its root system.

“In dry weather, you want that root system to grow down and get to moisture,” Smith said. “So you’ve got a healthier root system which is going to allow the plant to survive drought better and extend its growth into the hot time of the year. With a continuous grazing system, not only is the root system shutting off as it is being grazed hard, the root system is actually getting pruned back and getting shorter and shorter over time. You end up with a plant that has a very shallow root system so in just a few weeks of dry weather it no longer is able to get moisture.”

Smith recommends waiting until plants regrow to a height of eight to 10 inches before cattle are allowed to graze it again. This allows plants to have healthy top growth and a healthy root system. To maintain pastures long term, Smith said, it is better to feed some hay in a dry period so that when the rain does come, the pasture has a chance to recover. This means one field may be sacrificed – the animals stay in it while the other fields are given a recovery period. 

Rotational grazing is also advantageous during these times of high fertilizer prices, he said. By using rotational grazing, a farmer gets better utilization of the nutrients they put on the field. Additionally, a plant with a better root system will be able to get nutrients from a wider area in the soil so they can be better utilized.

“Rotational grazing provides better use of water and better use of nutrients as well,” Smith said.

The practice does not require dividing a farm up into many little paddocks which can be somewhat labor intensive. Anytime there is more than one pasture, rotational grazing is an option. Smith said most Kentucky farmers using rotational grazing are using three to four fields however there are a few doing it with a high number of paddocks. The biggest benefits from rotational grazing are seen when a farmer goes from having one pasture to having three or four. Beyond that there are incremental changes. 

For more information on rotational grazing, contact your local Cooperative Extension Service office.

Contact: 

Ray Smith, 859-257-3358