Common to many cattle producers around the world is the fear of wasting grass.“No blade left behind” could be a resounding chorus.
What many producers fail to understand is that what they leave behind is more important than what they take. In other words, the residual (living) grass left in a pasture following grazing is vitally important to the recovery and productivity of the pasture.
Pasture grasses need to be able to photosynthesize in order to grow. Photosynthesis takes place mainly in the leaves. When sufficient leaf material is left, pastures can recover more rapidly.
There are five key principles of livestock grazing management that, when applied, are beneficial to both the livestock and the pasture resource.
These five principles apply to irrigated pastures as well as on desert rangeland, although the scale and conditions of each certainly affect the specific application of the principles.
One thing should be understood right up front. There is no silver bullet that will work under all conditions or across all ranches.
With that said, the five principles are:
Adjust the rest period as pasture growth rate changes
At first glance, this principle might seem to only apply to irrigated pastures expected to be grazed multiple times over the growing season.
But it also applies to rangeland pastures. The rest in a rangeland pasture might be season-long or until seed-ripe.
In irrigated pastures, it should be recognized that pasture growth rates change according to moisture availability and temperature.
Irrigated pastures (cool-season grasses) typically grow rapidly in the spring, slow down considerably in the heat of the summer and then pick up some in the fall as the temperatures start to cool.
In contrast to that, warm-season grass pastures typically grow more rapidly in the heat of the summer as long as soil fertility and moisture are adequate.
Rest periods should be adjusted to allow a pasture time to recover from the previous grazing event before being grazed again. Often when individuals talk about overgrazing, they think there have been too many animals on the pasture.
Overgrazing really is not a function of animal numbers. Overgrazing is a function of time. Either the animals were exposed to the pasture for too long and grazed the new plant growth, or they are brought back to graze too quickly in the next rotation before the pasture has sufficiently re-grown and recovered.
Thus, overgrazing is not too many animals on a pasture and cannot be resolved simply by reducing animal numbers. Overgrazing truly is a function of time.
Use the shortest grazing period possible
The rule can help reduce one of the aforementioned causes of overgrazing. Animals should be moved frequently to avoid grazing new re-growth.
Shorter grazing periods also have a positive effect on the performance of the livestock.
Because animals are selective binge feeders, they eat the best forage first and often trample and foul much of the rest.
The longer they remain in the same pasture, the lower the quality of feed they are consuming. As this happens, intake falls, which in turn reduces animal performance.
More frequent moves will promote increased intake and improved performance. See Figure 1.
The length of the grazing period also affects how efficiently animals harvest standing forage. When short grazing periods are used, animals can harvest nearly 60 percent of the standing forage in a single grazing period.
When animals are allowed to graze a pasture on a season-long basis, harvesting efficiency drops as low as 35 percent.
Adjust stocking rates to match carrying capacity
Carrying capacity and stocking rate are often confused. In simple terms, carrying capacity refers to how much feed is there. Stocking rate refers to how much feed you take.
The stocking rate should be equal to the carrying capacity. It might seem easy to adjust the stocking rate to match the carrying capacity; however, if you consider the fact that the quantity of feed available is constantly changing as well as the fact that as calves, yearlings, etc., grow, their nutrient needs increase, so it can be a delicate balancing act.
Options to balance stocking rate and carrying capacity could include utilizing rented pasture or feeding hay if necessary. At times, it could also include either purchasing or selling animals.
Use the largest herd possible
This is simply the practice of putting smaller groups of livestock into fewer and larger groups. This can help increase the number of pastures, which permits shorter grazing periods and longer rest periods. Grouping animals also increases the stock density. Grouping animals can also be a good tool to incorporate decadent plant material or to incorporate new seed.
Use the highest stock density possible
At the University of Idaho Extension’s Lost Rivers Grazing Academy, we teach that stock density is the most powerful tool in the grazier’s toolbox. High stock density greatly increases grazing uniformity.
Animals will be more competitive with respect to feeding and consequently less selective. A short grazing period with high stock density will provide for more uniform utilization across a pasture.
High stock density also improves nutrient distribution. Low stock density allows animals to roam over a wide area. They gather pasture nutrients as they graze and then deposit most of those nutrients where they loaf, water and consume minerals.
High stock density puts many animals on the same pasture for a shorter period of time. This typically results in manure being distributed more evenly across the pasture, which can greatly aid in maintaining pasture fertility.
It should be recognized that stock density and stocking rate are not the same. A pasture could be stocked with one animal for 100 days or 100 animals for one day, and the stocking rate would be the same. The stock density, however, would be quite different, as would the effects on the pasture.
One animal for one day would result in some very patchy grazing with some plants being overgrazed and others getting big and wolfy (undergrazed).
Compare that with 100 animals for one day. Plants in that pasture will be more evenly grazed. The key here is to graze for a short period of time and move on to the next pasture or paddock.
As you apply these principles, it is important to monitor and adjust your grazing management.
While there is no recipe or silver bullet, these five principles are powerful tools that can improve pasture productivity and animal performance. 
