First, the soil- it looks pretty good overall. I wasn’t sure if it would be a mess from a century of farming, but it wasn’t. Most of the mineral metrics were medium to high, within the “desirable” ranges. The soil pH is a little low for optimal plant growth, so lime was recommended to raise the pH. And, nitrogen was low, so addition there was also recommended. Phosphorous, zinc and iron were all high; and that all translated into the forage measurements to some degree.
The forage testing was where I had the greatest interest. I wanted to assess important hoof health nutrients in the grass, to see where things might be going wrong for my sheep and all of their foot troubles. I suspected they were not getting enough copper, or possibly sulfur or zinc.
The overall nutrient numbers were excellent, I was thrilled with the results there. 23.6% crude protein (alfalfa hay is generally 16%, and lambs need at least that for good growth). The TDN (total digestible nutrients) was 72%, again beating alfalfa hay and being competitive with oat grains. (These are dry-matter #s, btw.) The detergent fiber measures were good too- overall, it measured as a highly digestible, high energy feed. Yay! And, that’s really not surprising, since our lambs grew very well on it, and our ewes maintained superb body condition while nursing twins and triplets all summer.
The trace mineral content is where things get interesting. There are different recommendations for appropriate levels, I’ve just grabbed some from common sources, I’m sure the values could be debated. There is less advice out there for sheep than for cattle, and we know they are similar but not the same. But this is a start.
- Sulfur was 0.36%-high. 0.1% is recommended, 0.4% is the max; and high levels of sulfur are antagonistic to absorption of copper, selenium and thiamine.
- Molybdenum was 4ppm-also high, ideal is <1ppm, and anything above 3ppm causes copper tie-up.
- The copper to molybdenum ratio was 3:1-low, and anything below 4:1 causes copper tie-up. Anything below 10:1 is considered copper-safe for sheep.
- Zinc was 37ppm-pretty high, 10ppm is considered sufficient for sheep. Zinc also binds with copper, but I’ve not found good sources to tell me what should be considered “high.” Zinc has always been present in my mineral salts too.
- The iron content was 597ppm, which is pretty crazy high. 50 is recommended, 1000 is considered the max. And levels above 400 are antagonistic to copper. It also binds with zinc, potassium, and vitamin E.
- Copper was at 12ppm; but 14-20ppm is recommended for sheep when molybdenum is >3.0ppm, so copper in this case is too low.
Notice any trends there? I think this paints a clear picture of copper deficiency, and that likely zinc and sulfur deficiencies are not causing my foot rot problem. It’s mind-boggling to note the three-way interactions, like that iron and zinc bind with copper, but also with each other. It’s further complicated that any mineral mix I buy contains even more of these copper-binding minerals that are all binding to each other too, so that’s just adding to the confusion. I feel more strongly than ever that my sheep need extra copper, but I’m in no-man’s-land to know how much.
Potassium was also very high, at 3.19%. 0.65% is recommended, 3.0% is considered the max. Now, it binds with iron, so hopefully it’s tackling some of my iron excess; but excess potassium also blocks magnesium absorption, which is the cause of grass tetany. So, something for me to be watchful for.
All in all, that was a well-spent hundred bucks, to give me insight into what’s going on with my soil and forage, and confirms my suspicions about copper. But it still leaves me short of answers of what to do about it! I’m still reading…