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Do Animals Know Which Minerals They Need?
This is the latest knowledge we have on how animals and their response to mineral feeding. It's an important part of building a mineral program to meet your herd's needs.
A number of companies in the U.S. sell free-choice or cafeteria-style mineral supplements. Their rationale is that ruminants will select the minerals they need and in the quantities they require for maintenance, pregnancy and growth.
Is this a good idea? Not according to many animal nutritionists who will tell you ruminants are incapable of consuming minerals in correct amounts to prevent or correct mineral deficiencies. They even cite studies support this claim. Unfortunately, researchers who designed and conducted these studies made questionable assumptions about diet selection.
Research at USU has demonstrated that ruminants must learn about foods and the consequences of eating those foods before they can make correct choices. Diet selection is not innate nor is it driven by instinct. This was not factored in by early studies on nutritional wisdom that focused on the innate ability of livestock to balance minerals in their diet. Listed below are assumptions made about these mineral studies and alternative explanations about how animals learn about foods and nutrients, including minerals.
Assumption 1.
Animals are “genetically programmed” to instinctively recognize nee
I’ve always wondered how an animal was supposed to know the difference between sodium chloride and sodium selenite. And given that the threshold for seeking sodium is relatively low and the limit is relatively high, if an animal chose Na2SeO3 rather than NaCl as the sodium source, and consumed it until the desire for sodium was met, it would either be getting a toxic dose of selenium or be trained that salt was bad. I don’t like either outcome.
And as Beth Burritt points out, this is a very expensive approach to what is usually pretty far down the list of limiting factors on animal performance.
Given that social learning is critical for young animals to make good nutritional choices and optimize growth and productivity, I am reconsidering a my decision to defer turning out my ewes and lambs until post- weaning in order to control internal parasite infections.
How long do you think the lambs would need to graze with their mothers to learn what to graze? Would a couple of weeks before weaning be enough?
Hi Emily,
I think they need more than a couple of weeks if you’re trying to get them to eat things that are not in the diet they had in confinement. My ewes and lambs run together all season (born on pasture in May, and self-weaned) and I’ve noticed a marked increase in the flock’s willingness to eat “weeds.”
What tastes good and meets nutritional needs changes over the course of a growing season, so the only things that your ewes are going to teach the lambs to eat are the things that are good for them in that two-week window.