Mob grazing (Ultra-High Stocking)
This session is reported at the end to lend continuity to the issue of fatty acid composition of pasture-fed meat and milk products of the previous sessions. How to change the fatty acid composition through primarily changing their diet. How to keep fresh vegetative forage in front of the livestock for the longest time possible to get the most favorable fatty acid composition as we know it to be today. How to market pasture-fed and -finished meat and milk products to fully participate in reaping the benefits of a value-added product. How to maintain that favorable fatty acid composition when cooking meat or processing the milk. Lastly, do we really know what is the most favorable fatty acid composition that is best for the human diet? It appears that we may have some good indications with some fatty acids and not with others. This is critical because we can only do so much to change the fatty acid composition. If we spend a lot of time, effort, and treasure to adhere to current health guidelines only to find out perhaps they were off the mark, we have wasted time, careers, and money chasing an ephemeral Holy Grail.
Mob grazing, as it is practiced today for cow-calf beef operations, is to allow the forage to go to late maturity. Yet, if we look back at the very first paper in these Proceedings, this is not going to bode well for the right type of plant fatty acids to promote enhanced fatty acid composition in the meat and milk of the livestock grazing them. Finishing beef feed-ers on late maturity grasses is not going to achieve a low n-6 to n-3 ratio. Some dairy farmers have begun experimenting with allowing the grasses to get more mature. As one dairy farmer has told me, he wants to be able to test for fatty acids so he knows that he is getting a low n-6 to n-3 ratio. If it starts to widen, the adjustment is to graze earlier, not later. He has remarked that he sees a ratio of less than one. This indicates that his cows are eating young vegetative grass and forbs. This is an outstanding low ratio. Presently, the cost of the milk test though is prohibitively high to do on a routine basis throughout the grazing season. Since the quality of the pasture is not the same the whole growing season, especially if switching from cool season grasses to warm season ones, it is really necessary to test at least at key times as forage growing conditions or species change. This way we either know we are producing a consistent fatty acid composition or we need to figure out how to keep it consistent by planning to have ample lush, vegetative pasture throughout the grazing season, or if that is not possible each season, find feed supplements that can be fed to keep fatty acid composition most consistent.
The other problem with eastern US pastures is, that as the forage matures, leaf senescence (leaf yellowing) begins to occur as the leaves get older. They begin to yellow as they shutdown to make way for new leaves or in reaction to drought. Leaving grass to grow ungrazed for 6 weeks or longer will cause as much senesced leaf as green leaf in the grazing zone, severely reducing forage quality. In drier climates, this becomes standing hay that remains edible (cured on the stem). In the subhumid and humid eastern US, it most often becomes moldy fast and is inedible and decays to mush. Even leaves that are not so old can become infected with various leaf diseases due to high humidity in the grass canopy that promotes their spread. Headed out grasses of any species will be avoided if there is something else (vegetative) available to eat. Orchardgrass has often been the bane of many a grazier if it is allowed to head out before it is grazed. However, any headed out grass will be avoided if vegetative material is available. Tall fescue, timothy, bromegrass, sweet vernalgrass, redtop, or whatever when headed out is going to be avoided unless it is all that is left to graze. This is not ideal, if trying to get good average daily gain or milk production. It can also lead to pink eye infections.
Two presentations were given. One emanating from Virginia in humid pasture country and the other from Missouri in subhumid pasture country with the dominant grass being tall fescue since both of them are in the Upper South tall fescue belt. As you will learn, there are various levels of stock density. This too plays a role on what is achieved in mob stocked pastures.
Benjamin Tracy*, Ph.D.
Mr. Doug Peterson*