Hi folks! Decided to make a separate blog post about the good response we got on the last post about essential minerals for horses.
I totally agree with you Seth,”weeds” probably are an underestimated asset as you brought me to ponder about it (poisonous weeds excluded). Weeds often have deep roots that reach down to where most minerals can be found, since minerals have high density they tend to wander down in the soil by time. Weeds may be low in proteins and energy and they compete with planted grasses and are therefore “hunted”; haven’t found any research about the “weeds”, but since their roots often go deep it can be suspected they are an important mineral reserve. Proteins and energy is easier to compensate for than low mineral content, so I say let the weeds live.
When we broke our (formerly bull) pasture it had been used only by moose and roe deer for over 20 years; we just fenced it, nothing else. It is indeed rich in a variety of weed plants but also the strongest of the original planted grasses like English Rye. Besides the Nokotas also have the Alder trees to chew on. During winter the Nokotas ate twice as much salt blocks and mineral blocks compared to in the summer!
About Seth’s very good question:“In your reading did you catch anything about the application of lime actually enhancing the deficiency of other minerals because the calcium bumped them from the soil colloids, much as many minerals can compete with each other when one is consumed in excess?”
I have read that a high PH enhances the mineral content in forage compared to a low PH. That would mean there should be higher mineral levels in Skåne and Gotland, southern Sweden. Don’t know if that is thoroughly checked. As you know, high PH traditionally means that fertilizers high in phosphorus and potassium (kalium) works better, so maybe that is what they mean by “enhanced mineral content”. Tampering with the soil is problematic since human knowledge tends to be more modest than we like to believe. Regular horse dung and grasses have been living in symbiosis for millions of years; manmade fertilizers can’t compete with that ;).
Since last November when our bellowed Nokota horses arrived (thanks again Emma and Seth) they on average consume a 10 kg salt block in two months, which after some algebra means 185 mg/kg bodyweight and day. This results in:
Na: 72 mg/kg bw, from 1,5%by bodyweight in grass hay they got an additional 3 mg/kg (RDI=17mg/kg bw)
Cl: 113 mg/kg bw, from 1,5%by bodyweight in grass hay they got an additional 80 mg/kg (RDI=135 mg/kg)
This means they perfectly supplied themselves with the missing minerals Na and Cl.
About the mineral blocks, our horses do not like it that much. We use the Horse-block from Granngården and they consume only maybe 10 kg in 4 months, meaning 92 mg/kg bw.
Two types of mineral blocks (Seth has kindly provided me with the specified contents) Horse “Häst” and Wildlife “Vilt” compared, also RDI and feed of grass hay equvalent to 1,5% by bodyweight. This is the results:
Häst Vilt RDI Hay 1,5%bw
0,11% /0,15% Magnesium 0,10 0,14 15 27 mg/kg bw
280/300 mg/kg Zinc 0,026 0,028 0,6 0,45 mg/kg bw
200/200 mg/kg Manganese 0,018 0,018 0,6 1,05 mg/kg bw
210/0 mg/kg Iron 0,019 0 0,6 1,95 mg/kg bw
400/2000 mg kg Copper 36,8 184 150 150 µg/kg bw
15/50 mg/kg Iodine 1,4 4,6 1,75 3,6 µg/kg bw
15/60 mg/kg Cobalt 1,4 5,5 0,4 1,8 µg/kg bw
5/30 mg/kg Selenium 0,5 2,8 1,75 1,5 µg/kg bw
My interpretations and comments on this are:
Mg: No supplement is usually needed but since it increases the absorption of calcium it is good for growing horses, though the content in the blocks seems negligible.
Cu: A good mineral to supplement for young horses, the Vilt block covers full RDI.
Zn: Negligible levels in both blocks.
Mn, Fe: Unnecessary to supplement, negligible levels in the blocks.
I: good to supplement (within limits) and it keeps Cesium away. (After the Tjernobyl accident in 1986 the Cesium fall out was high around Gävle, the highest levels in all Europe actually, Swedish moose and reindeer meat was poisonous for a decade)
Co: Not usually necessary to supplement, Vilt seems a little high.
Se: Usually very good to supplement, the Vilt is full RDI, Häst is a little low.
The only minerals I would like to see more of to complement a diet of good hay and the above blocks, would be Sulphur and maybe some Zinc, but again the mineral content in forage and all other plants our horses eat during a day is uncertain, we need to ponder further…