Ask the Equine Nutritionist – The importance of amino acids for horses
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Ask the Equine Nutritionist – The importance of amino acids for horses

October 25, 2019


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.

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