Grazing produces higher yields than mowing

Sunlight energy harvesters (farmers) managing grass and livestock who are keen observers frequently report higher forage yields and faster regrowth when forages are grazed instead of being mowed. In one case, a dairy farmer reported  40% higher forage yields over an eight month grazing season.

I attempted to track down an incomplete post I saw online that read:

Thiamine, vitamin B1, in cows saliva stimulates grass to grow 79% more quickly than if it were mown by a machine.

We’ve come to think of plants and animals as being separate, but it makes sense that their lives are intertwined. They evolved together after all. If grass is/was always grazed, then it makes sense to outsource this growth catalyst to the animals that graze it rather than the individual grasses. Nature is not only clever and a systems thinker, but also very efficient!

As humans, we like to think we have a reasonable understanding of how most things work, but my time on the farm has made me question that. There seems to be a lot we don’t know. I sometimes wonder whether we even know enough to ask the right questions…1

I was unable to track down a copy of this citation, but I did locate a few other references on this topic by the same authors. It seems probable there are other synergistic mechanisms in addition to thiamine that trigger faster grass regrowth. Livestock likely contribute some  growth enhancing microbes as well, which were not as well understood in this time period.

Whatever the various mechanisms may be, anecdotal evidence clearly indicates utilizing livestock as harvesters generates higher yields than using machines. And cost less to operate.

What other mechanisms does livestock grazing contribute to produce increased forage growth?


 1. Reardon, P. O., Merrill, L. B. & Leinweber, C. L. Proceedings International Rangeland Congress 1; 396-397.

Reardon, P. O., Leinweber, C. L. & Merrill, L. B. effect of bovine saliva on grasses. in Proc West Sect Am Soc Anim Sci (, 1972).

Reardon, P. O., Leinweber, C. L. & Merrill, L. B. Response of sideoats Grama to animal saliva and thiamine. J. Range Manage. 27, 400 (1974).

Reardon, P. O., Merrill, L. B. & Leinweber, C. L. Effect of bovine saliva and thiamine on regrowth of grass. PR Tex Agric Exp Stn Coll Stn (1975).