BeefTalk: Understanding Grazing Systems is Not Easy

By: Kris Ringwall, Beef Specialist

Grazing plans integrate the biology of plants and animals. Grass is the mainstay
of a grazing plan, and the subsequent understanding and implementation of
grazing can be overwhelming at times.

When the discussion widens to not only engage the grass discussion but the
animal discussion, as well, the participants have been known to get a little
testy. The concepts and associated processes in designing grazing systems are
complicated but well-understood. Compounding the active discussion is the
variation associated with whatever the species of animal that is selected to do
the grazing.

Additional input soon will erupt regarding the animal type selected within the
species selected. Take large or small cows, for example. Each time I address the
topic, general discussions, thoughts and opinions are advanced that far outweigh
the application of factual data relative to implementation of a grazing system.
So let me, in a more personal way, express some of the challenges that are
presented to me each time the subject is broached.

Several concepts must be placed on the table for discussion at the same time.
The list generally includes desired levels of animal performance, desired level
of forage utilization, and desired levels of quantity and quality of forage
production. The goal: Combine these three thoughts into a bottom line that
ultimately would produce the ranch a profit, outputs minus inputs, sustainably
through time.

Most producers will rely on history, adjusted for current seasonal weather
inputs, to help assess each year’s opportunity for grazing forage. But is the
system right? Is there something better? Those two questions trigger
considerable discussion in the range and ranch community. But let’s take each of
the three desires and look at how a logical discussion could unfold.

Setting a desired level of cattle performance requires an understanding of
cattle growth potential, but more importantly, it requires setting the size of
cow and meeting the cow’s nutritional requirements. Although range systems are
based on the metabolic weight of an animal unit, for discussion as cattle
producers, the 1,000-pound cow (including calf at side or dry) is the standard
weight of one animal unit. The 1,000-pound cow is allotted 26 pounds of pasture
forage per day to meet the nutritional needs of the cow.

Cattle performance or efficiency is not a function of setting up a grazing
system. There are differences in cattle types and efficiency, but that
difference does not impact the grazing system. All a producer needs to know is
the average weight of the cattle going into a pasture.

In regard to forage utilization, the age-old standard is still relevant today
and has not changed: Take half and leave half. Taking half of the forage and
leaving half of the forage remains the goal of many grazing systems. Systems
that remove more than half of the total forage production may be detrimental to
plant viability and could change plant populations. Leaving half is not based on
plant height but total weight, so more than half of the plant height will be
harvested.

Also, even though 50 percent of the total weight of the plant is utilized, only
25 percent of the total weight actually is ingested by the cow because 25
percent of the total weight is lost to trampling, is used for bedding, dries out
or decomposes through animal waste products. All a producer needs to know is
most grazing systems assume a 25 percent harvest efficiency of total forage
weight.

So why so much discussion of grazing systems? Harvest efficiency will vary as
cattle numbers are varied and with the intensity of the grazing system. If
additional grazing pressure is applied, the “take half, leave half” rule is
violated, but harvest efficiency may increase. By decreasing grazing pressure,
harvest efficiency actually goes down.

Another term, grazing efficiency, is used to represent the proportion of
utilized forage; it’s the “take half” that is ingested vs. wasted when grazing
density is changed. As grazing density (more cows per acre) increases, grazing
efficiency can increase. So there are components of grazing systems that vary
depending on the system.

Again, in setting up a grazing system, start with the concept of “take half,
leave half.” Of course, the desired levels of quantity and quality of forage
production are the most critical to understand because cattle weight is set and
forage utilization is determined by the grazing system. Forage quality
ultimately will be determined by the grazing system. However, producers must
know how much total forage can be produced, given the soil type, topography and
environment. More next week.

May you find all your ear tags.

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