There is a big difference between selective grazing where the animal is allowed to graze the species and parts of plants that it prefers and non-selective grazing where the animal is not allowed that luxury and has to consume most everything on offer.
To have the cattle thrive under non-selective management, the grazing periods need to be short so the rumen has a constant quality of feed coming into this wonderful batch system that is the rumen. Fresh feed about every two hours is the optimum, but this will depend on quality of forage on offer.
This takes some experience to do it successfully so the cattle are getting enough breaks and area to do well. You must monitor their success by fullness in the gut, good-looking manure, pre-grazing and post-grazing pasture mass.
This takes some work but benefits to the environment are huge.
Plants have the old growth removed, which allows the sunlight to reach the growing points, so better and more tillers are produced.
When animal density is high enough to make the animals graze non-selectively, this also allows the soil crust to be broken by the hoofs of the cows. This is necessary to allow for gas/air interchange in the soil.
Regrowth is enhanced by animal impact and cow saliva, which is now closer to the ground and thus closer to the plant growing points where it can be of more effect. Saliva from the cow gives a boost in plant growth versus mechanical cutting.
Increased plant density and therefore higher forage production is a result of this type of grazing if properly done.
Since animals are more concentrated and more plant material is consumed, this requires a longer recovery period, which allow desirable species time to establish and reproduce. Some desirable species need to be deferred for a whole growing season to establish and this fits well with the need to have a non-growing season reserve.
On the contrary, selective grazing carries many negative effects.
Cows leave the undesirable plant species un-grazed which allows them to set seed and reproduce.
Since the cattle don’t graze some plants at all, this means cattle need more area to graze. The consequence of this is that the stocking rate is lowered or the herd has to return sooner, this means there will not be enough time for the desirable species to thrive because cows will return and graze them before they have established and set seed.
The ratio of leaf to stem will be lower because the cows will selectively consume the leaves, which are higher digestibility, and reject the stems, which do not do photosynthesis but continue the respiration process. This reduces the energy reserves of the plant.
All these things go against pasture health and overall production and profit.
We need more leaf and less stem, not more stem and less leaf. A high proportion of leaf in relation to stem is needed for good animal performance and to capture sunlight so the roots give off exudates to feed the microorganisms in the soil. In turn, those soil organisms release nutrients in the soil and which they have captured from the air.
When we set aside a deferred area for the non-growing reserve, as I have discussed many times, the roots grow bigger and the individual plants get stronger. In these reserve areas, which should be moved around your ranch, new seedlings of desirable forage species can establish and reproduce.
This area needs a different management. I will discuss that in my next blog.