Protein Sources and Nutrition for Beef Cattle 2012

Protein Sources and Nutrition for Beef Cattle 2012


Hello, I’m Dan Loy, Extension Beef
Specialist from Iowa State University and director of the Iowa Beef Center.
What I plan to do today is spend a few minutes with you talking about some
of the issues that you may be dealing with this year as you look at protein
supplementation for your beef cattle. We’ve become accustomed to feeding high levels of corn co-products and distillers grains and in many cases
we’ve over fed protein in the last few years, and the current volatility in feed
prices has set the stage for some new decisions that many producers may not
have been accustomed to at least in the last four or five years. So just as a
general overview the topics that we’ll cover in the next few minutes is just a
little bit of background on protein and distillers grains and where we’re at
currently, a review of how we might go about looking at the cost of protein, and
I’m going to talk about metabolizable protein because that’s one way to
evaluate different protein sources in a useful way to determine whether or not the lowest-cost protein sources are useful
for a particular feeding program or situation, spend just a few minutes
talking about the BRaNDS program or other programs like BRaNDS that account
for the degradable protein or the DIP, and we’ll elaborate on that a little bit
further as we go through this, and then finally talk about some potential of
urea toxicity, some general thumbrules and how we might go about avoiding those issues if we’re looking at urea as a low cost source. For most of the last 5
years or so, the periods of 2007 to well through this year, corn co-products have
been cheaper than corn and in many cases, they may be again this year and when
that happens we have an economic incentive to feed just as much as we
possibly can. And so they become an energy source and when we do that, we
have an incentive to overfeed protein, so the need to balance many diets for
protein really hasn’t existed in the last five years because we’re always feeding more than we really need, but as protein, I’m sorry,
as prices for distillers grains have increased over the past months and at
times become more expensive than corn, distillers grains now becomes a protein
source. So how do we compare value and prices of different
sources of protein? On this chart, we have compared several common feed stuffs:
distillers grains, modified distillers grains, soybean meal, corn grain, urea, and
alfalfa and these are prices that I found in early October, average statewide
prices, and so in the columns we have listed here the percent protein, the
price either per ton, or per bushel in the case of corn, and then we calculated
the cost per unit of dry matter, and the cost per unit of crude protein. So this
is really the first step that you might take in evaluating sources of protein.
And we see that dried distillers grains, modified distillers grains, and alfalfa
all have very similar costs per unit of crude protein, 45 to 50 cents per pound
of crude protein in the ration. Soybean meal was a little higher at 57
cents per pound of crude protein, but there have been times this past summer
where soybean meal, particularly locally, was a lower, was a cheaper source of
protein than distillers grains or other corn co-products that may have been available. Notice that urea priced at $700 per ton because it is you
know it is a non-protein nitrogen source, is the lowest cost source of crude
protein in this example at 12.4 cents. So if that is the case,
and we are looking at evaluating sources of protein, so now urea we have
an incentive to feed as much area as we can utilize in a particular diet. So the
question becomes how do we know how much urea can be utilized? Well to do that the
next couple of slides are kind of an overview into how
ruminants, cattle in particular, digests different sources of protein and how we might determine if they utilize, can utilize NPN or urea. So there are
several acronyms that you may hear thrown about by the nutritionist and let
me just go through those very quickly, and it can become very confusing. First
of all, you know an animal consumes feed, the source of the feed we talk
about is crude protein, that’s the total amount of protein that the animal
ingests. You may hear your nutritionist talking about the DIP, or degradable
intake protein. That’s the protein that’s immediately degraded in the rumen to
ammonia and we’ll describe how that fits into protein systems in a little bit
later, but the proportion of DIP to feed stuffs is an important measure of
whether or not urea can be used. UIP, on the other hand, is the undegraded intake
protein. You may have heard talk about bypass protein, UIP is the bypass protein.
That protein gets the amino acids, are not degraded, they’re passed on
through the rumen, absorbed by the animal in their small intestine as amino
acid. Now ruminants have the unique ability of utilizing or potentially
utilizing NPN or non-protein nitrogen. This includes ammonia, it includes urea,
so non-protein nitrogen may be able to be utilized because the bacteria or
microbial crude protein (MCP) can manufacture their own protein, in other
words they grow and develop take the non-protein nitrogen along with
some energy and form microbial crude protein which can be absorbed by the
animal as protein as well. So basically if we can boil it down to a couple basic
principles, bacteria in the rumen can make protein, they utilize non-protein
nitrogen, but they also require energy, they require, they only require amino
acids for, the animal only requires amino acid for the needs that the bacteria can’t manufacture. Okay? And so there’s two
requirements that for the animal and that for the bacteria. And so if we look
at how a protein system or how we can evaluate whether different sources of
protein might be useful, let’s look at this particular schematic because this is really how we we do it. Crude protein that enters the rumen. Now
immediately when the feed enters the rumen, some of that protein is going
to be degraded to ammonia, that’s the DIP, degradable intake protein. Now if
this is urea, 100 percent of it will be almost immediately degraded to ammonia.
Now with natural feeds like soybean meal, even there a large proportion is
degraded to ammonia or as DIP. Soybean meal is about 75 percent DIP, which means 25 percent is bypassed or is part of the UIP, undegraded intake
protein, which goes to the small intestine, is metabolized, and contributes
to the MP, or metabolizable protein. So what happens to the DIP? Well it can
be used by the microbial crude protein or the bacteria to form microbial crude
protein. In other words, they grow and multiply and the protein becomes
part of their bodies and the animal actually digests the bacteria themselves,
but only if there’s enough energy in the ration either through feed intake or
energy density for those animals to utilize that. So there’s two parts of
this protein system: the DIP and UIP and then the energy that’s available to
utilize that. So as you work with your nutritionist, you should, and if
they’re using the metabolizable protein system, each feed stuff has a DIP value,
so we know the amount of degradable intake protein from your natural feedstuffs. What about commercial feeds? Well by law,
feed manufacturers are required to put on their feed tag the amount of
non-protein nitrogen, or urea, that is used in the manufacture of that feed.
Crude protein in this feed supplement was 36% and
that 11.2% was from non-protein nitrogen or urea. On this slide but this is how in
the BRaNDS program, beef ration and nutrition decision software, and I should
mention that there are other software programs that use
metabolizable protein so any software that is using the National Research
Council protein system for beef cattle will be able to evaluate in this way. But
what we look at, if you get a printout of the BRaNDS program, as we look
in the red circle you see the DIP, degraded intake protein, ratio and that
tells us in this ration that if this number’s less than a hundred percent, then we can utilize some urea or NPN in this ration up to about 100 percent. So there
would be the availability, or the possibility of adding some urea in this
particular ration. If you look up here on the line that says metabolizable
protein requirement – one hundred and forty seven percent for a mature cow,
we’re over feeding protein by almost 50 percent so we really don’t need to add
protein to this ration but if we did need protein, we could add a small amount
of urea or NPN. Beyond that, after it reaches 100, then we would need to feed a
natural source to meet the requirements of these animals. Now in cases where
energy is limited, there are possibilities, especially if we over feed
urea, that we can create toxicity and because of that, there have been thumb
rules developed through the years to aid in evaluating what the
maximum levels of urea that can be fed. And so here are those thumb rules:
maximum of one third of the ration nitrogen from NPN, urea should be no more
than ten to fifteen percent of a protein supplement, NPN should be no more than
one percent of the diet or three percent of the concentrate, and should contain no
more than five percent of a supplement used with low quality forages. Now if
you’re evaluating using the metabolizable protein system, you may
periodically be able to feed higher levels than these, but you need to evaluate it on that basis. So just to wrap up some final
thoughts. We need to evaluate the energy cost of the rations first. You know
distillers grains or corn co-products or the lowest energy source, in all
likelihood the protein requirements are already met, but in cases where we’re
feeding them as protein sources, then we need to look at what our alternatives
are, so compare your protein sources on the basis of crude protein but then make
sure that you use metabolizable protein to balance for those if you’re wanting
to include NPN, especially with low quality forages or in growing rations,
where the intake of energy may be limited to some extent. So thank you! Your
beef specialists will help you with questions and guide you through the
process if you do have additional.