Gerrish is a rancher, author, speaker, and consultant with over 40 years of experience in grazing management research, outreach, and practice.

Utilization is the percent of forage production that is used by grazing livestock and wildlife. There are two types of utilization to consider, and it is important for a serious grazier to know the difference. The terms are often used without fully understanding the difference in meaning, and that has led to confusion among pasture and range managers.

Temporal utilization is the percent of standing forage that we plan to harvest in a single grazing event. This is sometimes also referred to as “grazing period utilization.” Seasonal or annual utilization is the term that describes how much of the total forage production over the course of a year is consumed by livestock or wildlife. In set stock situations (continuous grazing), there is no difference in these terms, so we really concern ourselves only with seasonal utilization rate.

It is when we start moving cattle through a series of pastures with the expectation of two or more grazing events annually, as with management-intensive grazing, that our focus shifts to temporal utilization. Temporal utilization can also be thought of as severity of use within a single grazing event. Obviously, the inverse of utilization is postgrazing residual. Managing the balance between utilization and residual is the most important skill of a grazing manager because it largely determines both individual animal performance and the productivity of pasture and rangeland.

When we think about forage quality, most graziers understand that there is greater nutrition in leaves than in stems. The upper part of the pasture plant is mostly leaves, while the lower part of the plant has more stems. If we allow our livestock to only harvest the upper 20% of the canopy, they will perform admirably, as they are harvesting forage with a high percentage of digestible energy. This is also where the highest protein levels, bio-available minerals, vitamins, and other beneficial nutrients are found.

The deeper into the plant canopy we ask our livestock to graze, the lower the overall nutrient density of each bite. With the declining bite size of the second and third bites from a plant, the lower nutrient intake becomes. Because the volume of each bite is determined by the amount of indigestible fiber present in the plant, each successive bite is both smaller in volume and less nutrient dense. Thus, increasing temporal utilization rate results in reduced nutrient intake and declining individual animal performance.

From the land productivity side, green leaves are the main photosynthetic factory of the plant. As we utilize more and more leaves, daily photosynthetic output is reduced. The more days of the year that livestock are actively removing more leaf growth than new growth is occurring, the net productivity of the land is declining. High utilization rates over the course of longer grazing periods substantially reduces total forage production per acre.

A matter of time

The unfortunate perspective of many livestock producers is they must achieve high temporal utilization to get their “money’s worth” out of their pastures. The opposite is actually true. Lower temporal utilization rates will generally lead to both higher individual animal performance and enhanced forage production per acre. The key to success comes in balancing utilization and postgrazing residual across the continuum of time management.

While we do recognize the relationship between severity of utilization and individual animal performance, we must also understand this is a time relationship as well. If we use the classic “take half, leave half” utilization model, we find that 50% utilization with daily moves yields higher individual animal performance than does managing for 50% utilization over the course of a seven- to 14-day grazing period. The difference comes in the consistency of daily nutrient intake with daily moves compared to the declining pattern of nutrient intake over longer grazing periods. Thus, the same utilization target yields different results, depending on the duration of the grazing period.

If we make a comparison of total forage production between the daily move pasture and a similar pasture managed with seven- to 14-day grazing periods, we find the pasture with daily moves is more productive than the pasture using the longer grazing period because there are more days of actual recovery and growth taking place over the entire growing season when animals are being moved daily.

The bottom line is that we can more effectively manage the balance between temporal utilization, postgrazing residual, and the subsequent effects on both individual animal performance and land productivity when we do it in the context of time management rather than just spatial management.

This article appeared in the January 2025 issue of Hay & Forage Grower on page 19.

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