DR. LYDIA GRAY: Hey, SmartPak fans,
welcome to a special edition of Ask The Vet.
You may notice I'm sitting on this side, not that side.
I'm Dr. Lydia Gray, the Staff Veterinarian and Medical
Director at SmartPak.
This is Nerida Richards, PhD.
I'm going to let you introduce yourself.
DR. NERIDA RICHARDS: Sure.
Thanks, Lydia.
So I'm Nerida.
I'm an equine nutritionist from Australia, which is probably
quite obvious given my accent.
DR. LYDIA GRAY: I was going to say, far.
But obvious, it's true.
DR. NERIDA RICHARDS: I work as a consulting
nutritionist in Australia.
I formulate feeds and supplements
for companies all over the world.
And I also run the FeedXL.com website
which is a nutrition calculator that horse owners use to put
their horses diets together.
DR. LYDIA GRAY: Yeah.
Great.
We asked you to submit your horse nutrition questions
specifically, and in this segment
we'll answer one of those questions-- you'll
answer one of those questions.
I'm helping.
And then to see the other questions,
just click on the playlist at the end the video,
and you get to see them all.
So ready?
DR. NERIDA RICHARDS: Mm-hm.
DR. LYDIA GRAY: Our next question
is from tiffanyaperry from Instagram,
and she asks, "Can horses receive all of their chain
amino acids from hay?
What are side effects of chain amino acid deficiency
other than loss of muscle development?
DR. NERIDA RICHARDS: OK.
So amino acids come from protein.
So most things are made up of building blocks,
and the building blocks of protein are called amino acids.
There's 20 of them.
10 of them are what we call 'nonessential.'
So the horse, if it needs it, can just
make it in its own body.
So it takes building blocks from various places
for the amino acid itself and puts the amino acid together.
And then uses it wherever it needs to.
The other 10 amino acids we call essential amino acids.
And all that means is it must come in from the diet.
Because the horse can't make it for themselves.
So there's 10 of these.
And there's three that we really focus on,
because they're what we call the most limiting amino acids.
They're the ones that, when a horse runs out
of them, whatever it was trying to do using that amino acid has
to stop.
So yes, muscle development is certainly something
that the horse requires all these essential amino acids
to achieve.
But everything's built of protein.
So something you're probably really going
to notice if a horse becomes amino deficient
is declining hoof health.
Because the hooves require a lot of methionine,
which is one of the essential amino acids.
But every essential amino acid is in hoof tissue.
So that's one thing you would notice.
I mean, most of the body is made up of protein.
I'm sure we see bone development issues in young horses
when they're on amino deficient diets.
And there's really-- like organ health would suffer.
Everything would suffer.
Not dramatically.
With smaller deficiencies-- and you're right,
the first thing really we notice is just either a horse
losing muscle.
And this is really evident actually in lactating mares.
So mares with foal, because they have huge protein requirements
trying to make milk for their foal.
And if they're not getting the essential amino acids
in what we're feeding them, they have this huge reserve
in their own muscle.
And they, good mares would prefer
to use their own muscle reserves to make milk for their foal.
And so you will see these mares will just,
they've mined their own body reserves.
And so they will lose the top line,
they'll lose all the muscle of their rump
and they'll lose it all around their shoulders,
and they just become very angular looking,
because they have no muscle left.
Where if you feed them--
and we use in our breeding feeds,
we use a lot of soybean protein based
rations for breeding horses.
And we can maintain mares with the most glorious top lines
and rumps.
DR. LYDIA GRAY: Soy is a very high quality protein,
because it's got so many of the essential amino acids.
DR. NERIDA RICHARDS: Yeah.
Yeah, it does.
DR. LYDIA GRAY: They're high in lysine, which is the first--
[INTERPOSING VOICES]
DR. NERIDA RICHARDS: High in lysine, high in methionine,
high in threonine.
So we rank proteins with this-- we don't really
talk about it so much, but there's what
is called a biological value.
It may be old terminology now, but I certainly
still think of it this way in that the closer
an amino acid profile of a food ingredient
is to the amino acid requirements of whatever
is eating it, the higher the biological value.
So whey protein-- so whey protein,
isolate whey protein concentrate that bodybuilders
use as their post training supplement.
It's close to 100.
Like it's so-- the amino profile of whey protein is so close
to what we need as humans that it has got a real high--
DR. LYDIA GRAY: And eggs.
DR. NERIDA RICHARDS: Egg whites, yeah.
Egg white's down in the 80s somewhere.
But soybean is the highest ranked plant protein.
So out of all the plant-- because we don't feed generally
eggs or a lot of whey to horses.
We do love whey for horses, but it's expensive generally
and needs to be fed strategically.
Say soy protein is the most economical plant
based protein that also has a really good amino profile.
I think I found--
DR. LYDIA GRAY: Oh boy.
DR. NERIDA RICHARDS: I have two kids.
And I find now I try to explain things in very visual terms.
And I discovered that my kids building blocks
are actually a really neat way to show
people what happens when you run out of amino acids.
DR. LYDIA GRAY: OK.
DR. NERIDA RICHARDS: So if you imagine--
just imagine this is a piece of soybean protein.
DR. LYDIA GRAY: All right.
DR. NERIDA RICHARDS: And we'll say the blue blocks are
nonessential amino acids.
We don't know what they're called, we don't really care.
And then the red we'll say is methionine
and the yellow lysine and the green threonine.
So these are our essential aminos.
Now what happens when a horse eats a protein like this,
goes into the small intestine.
An enzyme, so a specific protein digesting enzymes, which I just
think of like a pair of scissors,
come along and cut this protein into its amino acids.
So they're all floating around in the gut, very, very
close to the brush border, so right
on the surface of the intestine.
And then they'll be absorbed.
So from the gut they'll be absorbed into the horse's body,
and they're now circulating around in the blood.
Now this particular horse has just done a bit of a workout,
and his muscles are going "I need to build up.
I want to be stronger."
And so the muscles will start looking
for the essential amino acids that it wants to put together
in a muscle protein.
Finds the soybean protein that's been absorbed,
and starts putting it back together.
Now it's not going to be exactly the same as the soy bean
protein, because it's no longer soybean.
But it'll put it back and will form a muscle fiber.
DR. LYDIA GRAY: OK.
DR. NERIDA RICHARDS: OK.
So similar.
It's all the same amino acids in there.
But it's now a muscle fiber and not a soybean.
And this is-- you know, you think
there must be, there must be millions of different proteins
in the world.
And they're all made out of these 20.
DR. LYDIA GRAY: The same building blocks.
Just different order.
DR. NERIDA RICHARDS: So different lengths,
different order.
They're all different.
So what I ask people to do is say, "OK.
Let's make that exact protein out of the proteins
that we've been set-- that we've been fed."
So your horse has been fed that protein,
my horse has been fed this protein,
and we'll see if we can reconstruct this protein.
Now the only rule is when you get to a color you don't have,
you have to stop.
Because you can't substitute any old amino acid in to a spot
where you don't have an essential amino acid.
Because then you're making a different protein.
DR. LYDIA GRAY: Right.
DR. NERIDA RICHARDS: OK?
DR. LYDIA GRAY: Got it.
DR. NERIDA RICHARDS: Let's see how we go.
DR. LYDIA GRAY: Here we go.
DR. NERIDA RICHARDS: Race you.
DR. LYDIA GRAY: Uh-oh, wait.
I think you've done this before, though.
DR. NERIDA RICHARDS: Many times.
[MUTTERING]
DR. LYDIA GRAY: Oh.
DR. NERIDA RICHARDS: Oh, Lydia had to stop.
DR. LYDIA GRAY: Oh.
DR. NERIDA RICHARDS: And now I'm doing it wrong.
DR. LYDIA GRAY: Because I don't have a yellow one.
DR. NERIDA RICHARDS: So yeah.
So you've run out of yellow.
So I have all the essential amino acids.
DR. LYDIA GRAY: Even though I have more of these,
I don't have a yellow, so I have to stop.
DR. NERIDA RICHARDS: Yeah.
Yeah.
So you now-- I mean the body would break that back down
or hang around.
But you can't build a muscle protein,
because you didn't get all the way to the end.
DR. LYDIA GRAY: So this horse wasn't
able to recover from his workout.
Or a four horse wasn't able to make it maybe to a five
because he couldn't-- it couldn't develop his top line,
because the muscle wasn't there.
DR. NERIDA RICHARDS: Yeah.
We see this a lot in Australia.
We have a lot of poor quality protein in our feed,
because soybean protein's quite expensive.
DR. LYDIA GRAY: In Australia.
DR. NERIDA RICHARDS: Because we have to import it.
DR. LYDIA GRAY: It's very cheap.
DR. NERIDA RICHARDS: From here.
So it's traveled-- Australia is a long way away.
DR. LYDIA GRAY: I've heard that.
DR. NERIDA RICHARDS: So it's expensive,
and we have a lot of cottonseed meal.
And the interesting--
DR. LYDIA GRAY: And what's the quality--
the protein quality of cottonseed meal?
DR. NERIDA RICHARDS: Well, it's low.
So it's missing essential amino acids,
but the interesting thing with cottonseed meal
is when they heat it to get the oil out,
gossypol, which is the toxic stuffing in cottonseed,
it deactivates itself, which is good, because then it
becomes safe to feed.
But its favorite way to deactivate itself
is by grabbing hold of lysine.
So there's lysine there, but it's got this gossypol hanging
onto it, and so it goes into the gut,
and it can't get into the body.
DR. LYDIA GRAY: It's not usable.
Not available.
DR. NERIDA RICHARDS: No.
So it's common for me to see mares
with foals on feeds that look like they have plenty
of protein, you know, they might be 16%, 18% protein,
and yet they're losing their top line
because they don't have the lysine
and they have to-- the mares have
to break like a whole muscle fiber
down just to get the lysine.
And we're on those poor quality protein.
So it makes a big difference.
Or they just, they will not-- if you have your horses
on a protein like this, they just
will not build top line, regardless
of how much you work them.
Because they don't have the building materials to do it.
DR. LYDIA GRAY: Yeah.
Wow.