This course will explore the concepts driving current food production science (population growth, urbanization, emerging affluence, resource constraints, and underlying biological limits) with the main focus on livestock production. Each of the major food animal species (dairy, swine, beef, and poultry) will be covered in terms of their universal life cycles, constraints to production and emerging societal issues. Throughout the course, we will tackle some difficult and important questions: What are the major health benefits and potential concerns regarding the production and consumption of animal products? How does animal production affect the efficient use of resources and impact our environment? Can cost of production be reduced to meet growing demand for animal products around the globe while maintaining health and safety for both animals and consumers? What are the different types of animal food production systems? Myths and misconceptions surrounding the animal food systems will be discussed. We’ll also look closely at some of the global issues, problems, and challenges in these food systems which scientists, farmers, and veterinarians, are attempting to solve through collaboration. Lectures will be delivered by several experts from the University of Pennsylvania, School of Veterinary Medicine who are intimately involved in the study and advancement of animal production systems. The course is geared towards learners who seek a greater understanding of animal food systems as well as those who might have never visited an animal farm, but have a desire to learn more about where some of our food comes from and issues surrounding sustainability.
The Beef Cow Life Cycle Part 2
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En provenance du cours de University of Pennsylvania
Feeding the World
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Beef Production
The final module of the course focuses on beef production systems. We will examine the production system and life cycle of U.S. beef cattle. Then, we'll address animal health as well as public health issues. Finally, we'll finish the week with a discussion about the international beef industry.
Rencontrer les enseignants
Dr. David GalliganProfessor of Animal Health Economics
School of Veterinary Medicine
James FergusonProfessor of Nutrition
School of Veterinary Medicine
Generally, they're in that feedlot for two to three months and
exposed to a high concentrate of grain as well as forage.
We, typically, will see 40% to 60% of the total ration fed as grain.
And of course, what this it is allows a higher weight gain per day to achieve.
So these animals end up reaching market weights much sooner than the cows,
the steers that are placed on grass.
If we step back and look at what the common feeds are throughout
the whole life cycle of the animal, we can see that for the most time,
the animals are exposed to forages in the form of pasture or harvested hay.
So they compete very little with human consumable grain,
such as corn, and maybe soybean meal.
The only grain that's fed to these animals during this time might be a creep feed,
might be offered to the young animal to encourage it to have a higher weight gain.
And also to get it used to eating feeds other than the mother's milk,
so there's a creep feed.
Then if they go into the feedlot, then of course, they're exposed to a much higher
concentration of grain often 40 to 60%, of the total ration will be grain.
And generally, they're in this phase of their life, for maybe 60, 90 days.
So most of the animal's life is on grass.
And then of course, during these last few months, they might be exposed to grain.
Now, this can vary in the industry depending on what the cost of grains are.
If grains are very expensive,
then the beef animals will stay out on pasture longer.
If grain is very cheap and
we have a bountiful harvest, then they'll move them into the feedlots.
So the beef industry provide a wonderful rheostat to deal with the variation
that might occur in terms of crop yields and corn harvest.
So it's a wonderful way to deal with excesses of inventory, or
when we have less than adequate yields, we can keep them on grass longer.
Now, a common metric that's used is what's called feed efficiency.
This looks at the total kilograms of feed fed to the weight gain that's occurred.
And while this is a rough number,
it has some nuances that I think are worth explaining.
If we look at the feeds fed to a beef animal, and
we'll focus initially just on the feedlot situation.
We'll see about 40 to 60% of the ration can be forages,
or that the animal is on pasture.
Then it can be exposed to grains, and
grains are complex and that some of them can be by-product grains.
These are grains that have no use in the human food system,
such as wet brewer's grains, or cotton seed, or candy waste.
And then, of course,
they can be exposed to grains that do have alternative uses in the human food system.
And so we often talk about the total pounds of feed fed
to the amount of weight gain that has occurred.
>> This is a candy meal, it's a byproduct we utilize,
had some candy in it and some licorice sometimes.
It's a blend that they put together that
we can utilize instead of having it hauled to a landfill.
This is a corn gluten product, it's a byproduct
from the process of corn starch manufacturing.
And we utilize that also to supplement energy in the feed.
This is corn a [INAUDIBLE] stored in horizontal silo as opposed to a vertical.
It is put in here, and we pack it down with a tractor or
a weight and just keep driving over it to make it tight.
And it's the whole plant ground up or chopped up for feed.
>> With that eight and a half pounds of feed conversion,
I think you have to keep in mind that the vast majority of that is forage.
They're on about a 70% forage diet when the cattle come into the feedlot,
and a 30% grain.
So if you calculate that out,
it's a lot less grain than what you might think are going into the cattle.
As they get finished, that green increases, but we never go above 60%.
So even at the finishing level, our conversion rate is still
in that eight pound range, with most of it being forage.
>> Now, when we look at the industry typical numbers you might see, and
this is a an analytic, that's interactive.
Typically, we might see 8 pounds, 8 and
a half pounds of feed, of total feed per pound of gain.
But of course, we need to look at this in a little more detail.
If we look at just the grain that is fed,
we will see a number that's closer to about 5 pounds of grain per pound of gain.
And furthermore, if we look at the amount of the grain, that is true grain not
byproduct, we're down to 3.3 pounds of feed per pound of gain.
And so we can see as we start to look at these feed efficiencies and partition them
into the types of feeds, that the beef cow is actually starting to challenge or be
closed to what we see in feed efficiencies in the poultry and swine industry.
In poultry and swine, we typically might see three to one ratios of feed to grain.
But those industries use considerably more grain in their feeding and
have very little, if any forage base.
Furthermore, when we look over the entire lifetime of the animal,
m ost of the weight gain of the animal is occurring when it's on pasture.
And if you look at the feed grains then that are used over the lifetime weight
gain, we're down there at about 1.5 pounds,
1.4 pounds of feed per pound of gain.
So it's very critical to look at what the the types of
feeds are when we look at these feed efficiency numbers.
In other words, all pounds of feed aren't the same.
And what dominates the life of a beef animal is, of course, the forage base.
We're going to look at three different types of feeding systems.
We'll look at a low gain per day.
This would be a steer that is raised predominantly on pasture its entire life.
So grass fed, a pasture based system.
Then we can look at a mid gain.
This is where an animal might be exposed to a little bit of grain or
concentrate feeding, and the rest of the ration being the forages.
And then, we'll look at a high gain per day.
And this is where the animal will be fed
in the beef lot situation where we expose them to a lot of concentrate.
And let's look at the situation where our desired goal is to have these animals
finish out at about 1,100 pounds.
This is a body weight that we like to see deers achieved because they tend to
harvest the maximum amount of profit per pound of gain at that weight.
Now, the cost, the feed cost, of course,
is going to be a function of the weight gain.
So as we expose the animal to these higher gains, we're going to be feeding more
concentrate, and therefore, the expense is going to go up.
And in this example, we'll use a conversion of feed energy into a pound of
gain of 1.8 to mcals of energy per pound of gain.
So when we look at this,
here's a graph showing the time to reaching that finishing weight.
And we can that on the low weight gain of 0.7 pounds per day.
It takes almost four years for that animal to reach its finishing weight.
And so that's a really extended long time that the animal has to be managed and
cared for to achieve this finishing weight.
As we expose the animal to higher and higher levels of concentrate,
we see that we can achieve that 1,100 pounds much, much sooner.
If we look at the economics of this to the producer.
So here, we're looking at the three different systems, where we have the pound
of gain at 0.7, the 1.9 pounds of gain, and 2.9 pounds of gain.
We can see that the daily return are timed
to finishing weight is going to be very extended, as we saw on the previous graph.
If we look at the economics, we can see that the return per day for
the high weight gain is much much higher
than the return per day on the low weight gain strategy.
And so it's because of this economic scenario, that we see a lot of the beef
industry moved to exposing animals to this concentrate feeding
system called the feedlot, and exposing them to more and more concentrate.
Of course, if the cost of feed goes up, and the cost of that gain goes up,
then it will see that then the return start to migrate down.
And maybe we expose the animal to more of a feeding
system that's based on the forage base.
So in summary, the beef life cycle generates replacement heifers,
as well as steers for the meat production.
The life cycle can vary as a function of available feeds and
resources, as well as our costs.
So as the cost of grains go up, we'll feed less of it to cattle, and
they'll be exposed to longer periods of time on grass.
Forages, pasture, dominate the cow's diet throughout the life.
Certainly, the replacement phase is dominated by pasture
as well as the brute cow, and the early phase of life of the steer.
Grains can supplement forages and lead to higher gains per day that
ultimately reduce the time to market improving producer economic returns.
And so as we look at the livelihood of the beef producer,
this is going to be of deep concern for him.
Economic conditions, the price of beef, costs of forages and
grains will ultimately influence which pathways are pursued in any given year.
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