Stocking density is a practical tool for managing animal diet selection and animal performance, as discussed in a report by Doug Peterson, rancher and Natural Resource Conservation Service State Soil Health Conservationist from Missouri.
The report was included in Rangelands, Volume 35, a publication of the Society for Range Management.
Peterson and his two rancher friends, Mark Brownlee and Tim Kelley, are experienced graziers who spend many hours observing and interpreting what is taking place at the ground level on pastures and grasslands.
Stock density refers to the animal live weight, on a per acre basis, for a grazing period. The three authors have experience with stock densities of 1,000 to 500,000 pounds per acre and about everything in between.
At the higher stocking rates, livestock can become quite aggressive in their grazing habits. The authors suggest two factors that cause animals to change their diet selection: becoming familiar with forages they were not required to eat before and being in such a confined environment that they have to compete with herd mates for the next bite of grass.
Cattle managed at low stocking densities are used to having enough adequate forage available to be very selective in grazing. They must overcome this grazing behavior when changed to a higher stocking rate. Changing the stocking density can affect animal performance, and the grazier should not allow animal performance to be sacrificed to achieve the higher stock density. Some situations have occurred where competition has caused livestock to eat the thatch off the ground and bark off the trees. The authors urge managers to ensure that animals have adequate levels of nutrition at all stocking densities.
“Anytime we create an environment that causes animals to eat something that doesn’t meet their nutritional requirements, we are going to have major problems,” they say. They emphasize that even in a high stocking density situation, graziers allow enough animal selectivity over the course of a day to take in the forage quality and quantity needed to meet their nutritional requirements.
“Soil health drives everything,” Peterson says. He indicates that one of the biggest benefits of high stocking density is in the improvements to the soil. Regardless of whether you’re in a 10-inch rainfall area, or a 40-inch rainfall area, the health of the soil drives almost all environmental processes. Grazing management has a direct impact on soil biological activity, mineral cycling, soil organic matter, water infiltration and water evaporation from the soil surface.
Higher stocking density grazing requires intensive management and intensive management is consistent with short duration grazing and longer recovery periods. The longer recovery time allows forage plants to develop more above-ground and below-ground level biomass. The taller canopies help reduce rainfall energy and increases water infiltration into the soil. The resulting greater root mass is effective in reducing soil compaction.
The soil is home to many small, microscopic creatures that need a healthy habitat in which to live and work. They, in turn, create an environment that supports healthy, productive plants that protect the soil surface. The longer recovery periods tend to result in longer root systems that reach deeper into the soil and pull up minerals from depths not accessible by shorter-rooted plants.
Properly managed higher density grazing with adequate recovery periods can result in forage for livestock that is nutritious and supports a healthy soil environment.