It won't be news to you that we have a bunch of farmers in New Zealand!
You knew that, right?
Some of them have made some dramatic discoveries during their lifetime, concerning their stock's health/sickness, from being placed in a dire position and having to radically alter their stock management practices in order to survive financially on the farm. "Triumph through adversity" (like during the War) etc. I believe it can be instructive to learn of instances where animals' health sometimes change rapidly for the better. Sometimes this knowledge is transferable to us human types also. Take the instance of one farmer we shall call Bruce. Bruce was farming normally and noticing a gradual decline over a decade or more, in growth rates, together with frequent and increasing levels of sickness, (often from worms/ parasites) etc. They were getting thinner and often dying (the stock not the parasites-THEY were getting fatter! ). Yet Bruce was considered a good farmer; he did all the normal farming tricks and to all intents and purposes farmed his patch well. His farming chums would have called Bruce a fair dinkum man of the soil and all round good joker (or some such-you get the drift?) and the farm "looked" a "Picture". The grass looked "lush". What could be "crook" (as we say)? He was spending an inordinate amount of his working day playing catch up and desperately trying to cure his sick stock; the vet was a frequent visitor.
Then he tried adding various trace minerals to their diet in one way or another. Won't bore you with the methods-this is a family show after all! He even spread them over the ground using a top-dressing aeroplane. How cool is that? Apparently the results were both quick and profound. His stock gained weight instead of losing weight and were all-round healthier and performed better on all counts where it matters on the farm. As a bonus, his medical, fertilizer and vet bills dropped significantly. So, more profit with less costs/inputs. Win win situation and farm / farmer saved. Hay presto.
I am most concerned about the lack of (particularly) zinc, selenium, boron and copper in our soils here in N.Z. but others may well be in short supply through either not being here in the first place or through depletion over the years. If it isn't in the soil then it won't be in the food will it (unless it is "fortified" ha)?
So the moral of this story is that you should take your trace minerals seriously and if they ain't in the soil (and they likely will have packed their bags and left in a huff in the 1950s or 60s sad to say) then you had better try getting them elsewhere. So there you have it, more info from Down Under. Live long and prosper.