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Myth Buster: Do livestock self medicate?

Do livestock (sheep and beef cattle) self medicate? Or find what they need if it’s available? Dr Shawn McGrath, Senior Lecturer in Animal Production at Charles Sturt University joins us to discuss the science behind the myth. Watch the short clip below to hear his thoughts.


OK, so I’ll just move on to the myth buster that Jane gave me, so her question was do livestock – sheep and beef cattle- self medicate or find what they need if available? So I did a bit a little bit of research on the topic.

And I’ve listened to a few talks from Fred Provenza when he’s visited Australia over the last decade. He’s been here at least twice that I’m aware of. However, I also found this quote in the Suttle textbook which said, Contrary to popular belief, appetite for a mineral, particularly trace minerals, is not a reliable measure of an animal’s need, nor can be relied upon to correct any dietary imbalance. So just because animals are eating a supplement doesn’t mean necessarily that they need it. So don’t take consumption to be a confirmation that there is a deficiency. And they won’t necessarily eat supplements to correct an imbalance, that they do have.

There is some evidence to suggest that animals will sometimes select diets that meet their mineral and vitamin needs. But it’s not consistent. And the animals basically. My conclusion on it or my take on it is that the animals just can’t be relied on in terms of their behaviour.

It could also be driven by other factors. For example, palatability, natural appetite for particular supplements such as salt. So ruminants have a natural appetite for salt. If you put salt in the mix, they’ll probably eat the supplement because that because they like the salt.

In terms of self medicating, there is certainly evidence that animals will avoid feeds that they associate with negative experience. So, for example, I was reading a paper with bloating sheep, which showed that animals learnt to avoid the feeds which were causing them to bloat in a controlled experiment.

But obviously, if we don’t give the animals a choice, such as if they’re in a feedlot where they’re at risk of acidosis, they’ll probably still consume the ration. But perhaps at a lower level. There’s also some evidence in the literature of self medication.

However, again, not consistent. So examples: I was reading an article about tannins in goats for treating Haemonchus. And the hypothesis that this particular study was that the animals would self medicate with the high tannin diet. However, this was disproved in that particular study.

The goats did seem to select a diet to balance the nitrogen intake, but didn’t seem to have anything to do with dealing with the Haemonchus infection.