ill thrift

Farm animals are subject to all sorts of conditions & diseases with exotic names: bloat, braxy, fluke, hoose, scour. These can be congenital or infectious or some sort of trace-element deficiency. It can be difficult of diagnosis: the symptoms of too-much selenium overlap with those of too-little. Once they've got a reliable diagnosis, farrrmers want to knock it on the head in a way that is timely, effective and cheap.

Thyroxine is essential for growth and metabolic health in humans and livestock and also incorporates iodine. Just a little I goes a long way, but if your soil is deficient, iodine won't appear in the fodder and something must be done. Likewise with vitamin B12 and cobalt. Lambs which get along fine, and meet their weight markers while on their mother's milk, sometimes fail to thrive after weaning. This is known as ill-thrift or [cobalt]-pine, and becomes a known thing on some farms because,

 like our selenium deficiency, there isn't enough cobalt in that soil. It then becomes an addition on the long list of ThingsToDo to prepare the product for market. The treatment is known, readily available and the cost-benefit is clear: "Oral cobalt supplementation costs less than 1 penny per 25 kg lamb. Production losses from poor growth and delays to marketing may cost £10-£15 per lamb." But it's a time-eating pain to bring the lambs in every month and given them the cobalt or vitB12 that they need.

Well, it turns out that some varieties of willow Salix spp. are hyper-accumulators of cobalt and lambs have a taste for the stuff. It also grows fast, especially in the wet soils that are suitable for sheep . . . because barley or spuds or mangolds or cattle aren't an option. A trial in NE England sponsored by The Oglesby Charitable Trust, has been investigating the effects of feeding willow to lambs. 

It's interesting that lambs are avid for willow; because our sheep feel the same about ivy Hedera helix. When we had snow followed by 5 days of sub-zero temps two weeks ago, we were a bit caught with our pants down. We had only one 25kg bag of mmmm good sheep muesli but that's like dessert and not enough to sustain 15 sheep indefinitely. We also had a big round bale of hay but about half of each armful gets trampled into the snow and/or shat upon. Accordingly I coursed about the property looking for the biggest, greenest, nearest sources of ivy and dragged them up to the top field where the sheep where sheltering in place. It's not clear if ewes love ivy because if supplies a dietary deficiency or because it is green and available in the winter.

Back when I was still active in science I spent a few years facilitating an enthusiastic young scientist towards his eventual PhD in Lithium Sudies. One of the sub-projects which got published was an investigation of whether different species of plant preferentially extract lithium from the soil. It turns out that they do:

The local garden centre was selling seeds for oilseed rape Brassica napus; cabbage Brassica oleracea; sunflower Helianthus annuus; tomato Solanum lycopersicum and bittercress Cardamine hirsuta. The Effective planted them out, dobbed the soil with lithium and measured the concentration of that element in the leaves and stems. Figure 2, shown above, suggests that some species, like bittercress, suck it up goodo while others, like tomato, won't have anything to do with the stuff. Crap-detector: you shd be suspect of any paper where none of the authors and none of the editors noticed a typo H. annuus and also that the publishers MDPI are flagged as predatory: they will publish any-old-shite so long as someone pays the page-charges. So a pinch of lithium salt here although the observation can be easily replicated. 

And it is known that some species, like the daisy-adjacent Berkheya coddii, can hoover nickel and cobalt out of the soil. This can be an elegant way of remediating old industrial sites or mine tailings.