One of my big questions throughout this whole beginning farming adventure has been “how many sheep can my farm support?” Our potential grazing area is limited and I have no desire to overrun our property and destroy this beautiful landscape and pollute our waterways as a result of housing too many animals. Rene of the Pierce County Conservation District informed me of “Animal Units” (or AU): one AU is equivalent to 1000 pounds of livestock, be it cows, sheep, goats, etc. Estimating AU is useful, as it can help a farmer plan accordingly what kind and how many animals they can potentially support on available grazing space. Different climates and landscapes can support differing amounts of AU, so it’s beneficial to know what kind of landscape you have available, what kind of grasses or forage is growing there, and what kind of nutrition your animal(s) need.
While I don’t yet know for certain what kind of grasses are growing in our fields, I do know there is quite a lot of vetch (which is good), along with the ever-present blackberries, some thistle, and scattered tansy (which is bad). Vetch is a good browse for critters, as it is very high in protein and digestible matter, very palatable for most livestock and it’s additionally great as a potential green manure. I’m not sure how well the sheep will help to control the blackberries present on our property, but I do know that goats will do some serious damage! I do plan to acquire goats at some point, but not until we have sufficient housing and fencing for them (currently, we have neither). Goats and sheep will both eat the thistle blossoms, and that will help control the spread of that particular weed. Tansy, on the other hand, is a noxious weed and I will need to remove the plants by hand before any livestock sets foot on my property. Tansy is very poisonous, and while most animals are smart enough to not eat it, I don’t want to take any chances!
So! Back to AU: I’m currently basing my estimations on the average weight of a Border Leicester ewe, which is about 130 pounds. At 130 pounds, approximately 7 Border Leicester ewes will make 1 AU. So what does that mean in relation to carrying capacity on my little farm? Answer: I have no idea, I’m still trying to figure that out. The needs for my farm and my future sheep will be different than most farmers: I’m not looking to raise lambs, “finishing weight” means jack squat to me, and I don’t necessarily want to increase my flock on a regular basis. I just want to have sheep for wool production. Maybe that means my farm’s carrying capacity will be greater, since I don’t have to worry about the nutritional intake of pregnant or nursing ewes.
Very much looking forward to having a farm planner come out to give some guidance and let me know what is reasonable for livestock numbers!
https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/idpmstn9390.pdf
http://www.whitecloversheepfarm.com/prl-articles/Farming_CarryingCapacity.pdf