Cattle

Brief Overview: Grazing Sciences

Cows are picky if given the opportunity to selectively graze. They will return to the most delicious grasses as soon as new growth appears while letting the less palatable (but equally nutritious) grasses reach maturity (thus no longer nutritious), seed and eventually crowd out the good stuff. With the Managed Intensive Rotational Grazing (MIRG) system, the animals are given the exact amount of pasture that they can eat in 24 hours before being moved to a fresh paddock which encourages the animals to take a more “mowing” approach opposed to selective. Each paddock is rested until it regenerates.

Grass grows on an “S” curve as demonstrated by this excerpt from the California Grazing Association’s publication titled Principles of Controlled Grazing (PDF):

PrincipleofGrazing

Since I am working with so little land (~6 Acres with trees removed), I want to manage it as efficiently as possible. The next question is how much do I let the grazers mow the paddocks? According to these fantastic demonstrations on Forage Decision Aids by the University of Kentucky, we can directly compare the regeneration of Orchard Grass of the 6 days following simulated grazing to 3.5 inches vs mowed all the way down to 1″.

Combined with various different university studies, most grasses regenerate best when grazed to ~10 cm. At this length, grasses retain enough photosynthetic tissue to create the energy required for regrowth without having to use reserves stored in the root system.

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GIS Planning

Mapping the Farm!

My first step to analyzing the viability of my pasture was to produce a digital map. I grabbed some high resolution imagery and drew the boundaries, otherwise known as digitizing or interpreting aerial photography in the Geographic Information Systems (GIS) industry. After digitizing the pasture, an array of powerful tools are opened up to me to perform geospatial analysis.

Base Aerial Image

Base Aerial

Boundaries Drawn for Pasture

PastureBoundries

 

As you can see, pioneer species of trees have popped up sporadically. I’ve decided to work with them rather than against them as they have created wildlife corridors for deer. However I understand that I cannot consider the area beneath the trees as good grazing material. So my next step was to digitize the trees in GIS software, then cut them out of my pasture polygon.

Pasture with Trees Removed

PastureNoTrees

Geometries like area, perimeter and anything else needed can be instantly calculated:

Acreage of Pasture (top is with trees removed)

Acrage

With these basic data creation steps complete, I can move forward with more advanced analysis to plan the farm. Stay tuned!

Please don’t hesitate to leave comments if you catch any errors in my methodology, can offer feedback, have questions or would like me to perform similar GIS analysis for your property!

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