I'd like to talk about global food security and

what about livestock systems and how they relate to food provision.

Livestock are important worldwide.

About 33% of agricultural gross domestic production it comes from livestock.

They're especially important in developing word to subsistence farmers.

They're an important source of economic value to have livestock.

The developing world meat production has increased from 1980 to 2002

from 45 million metric tons a year to 134 million metric tons a year.

And it's primarily through increases in pig and

poultry production in East Asia that has resulted in that development.

Livestock contribute about 17% of kilocalories and

33% of protein consumption worldwide.

So they're an important source of energy and protein across diets for humans.

Other benefits of livestock,

they provide essential income for about 1/7 of the world's population.

Over 1 billion people in Africa and

Asia receive significant income from raising livestock.

And it accounts for

anywhere from 2 to 33% of household income in pastoralist households.

It's important as a source of income for

many women who are the primary livestock keepers in these countries.

Mixed crop livestock systems produce about 50% of the world's cereals.

And manure from livestock is an important source of fertilizer in these systems.

Manure's a source of nitrogen for about 23% of mixed cropping systems and

about 12% of all nitrogen used globally.

So animal manure becomes an important source of fertilizer.

In addition, still in many countries, buffalo and

cattle are important sources of draft power particularly in Africa and Asia.

And consumption of crop residues and waste products of food processing

is an important source of feed for many of our ruminants and many of our livestock.

So they become a way of removing some of this inedible material

into edible products through livestock consumption.

We can see in this slide that meat production in metric tonnes

has increased dramatically from 1960 to 2010.

And that increase in meat production has been largely driven by swine and poultry.

There's been small increases in beef production, in buffalo,

but the major drivers have been in poultry and swine production in the world.

Very little change in goat and sheep.

And some of the other lesser valued species like rabbits and

other game species had only shown very small changes across time.

When we look at the proportion of the global meat production,

the big three are swine, poultry, and large ruminants, cattle and buffalo.

And then others contribute a small component.

When we look at meat, I mean milk.

Excuse me, when we look at milk,

we see that cattle are the major supplier of milk in the world.

The second largest group is buffalo, with small components of sheep and goats.

For eggs, there's over a trillion

eggs produced in the world each year from hens and other chickens.

And so these are the major sources of food that go into our human food chain.

It would be meat from poultry, swine, and large ruminants, like buffalo and cattle.

And really, milk from cows and then eggs from chickens.

What we need to consider though is the foundation of our entire food system

are plants.

Plants capture solar energy, they take CO2 out of the air, they take water out of

the air and out of the ground, inorganic nutrients, and they make carbohydrates.

The maximum conversion is about 4.78 mega cals per square meter of

solar energy gets converted into about 68 grams of carbohydrate per square meter.

And that represents about 0.27 mega cals of energy.

So plants are about 0.5 to 1% efficient in capturing solar energy.

The most efficient plant in the world is sugar cane.

It captures about 8% of solar energy into carbohydrate.

Now, through cropping, through agriculture,

we increase that efficiency to about 5% of captured solar energy.

And we do that through density of plants, how densely we plant fields.

From selection of plants with more vertical leaf canopies,

so they have less shadowing or shading of each other, and

that improves the conversion of light to useable biomass.

In plants we have two main components of a plant.

We have the seed structure, which is edible, which contains most of the starch,

edible by humans.

And we also have the fodder or the straw component,

which is composed largely of cellulose, inedible to humans.

We have two, really, forms of carbohydrates produced in plants.

We have simple carbohydrate sugars, which are primarily glucose and

other small carbohydrates that are rapidly absorbed and available by people.

They are a small component though of most of the carbohydrate in plants.

Sugars are really on their way on to getting incorporated into complex

carbohydrates in plants, which are polymers of glucose.

We have starch, which is digestible by mammals.

Over 90% complete digestibility.

And we have fiber that's not digestible at all by mammals.

And it's composed as the plant cell wall, which gives it structure and rigidity.

And it's composed of hemicellulose, cellulose and lignin.

The question is, billions of years of evolution, animal enzymes cannot

digest cellulose, the most common polysaccharide on the planet, why?

Well, it has the small difference in linkages.

Starch is linked by what is called an alpha 1-4 linkage,

whereas cellulose is linked by a beta 1-4 linkage.

Here we see the differences,

if we look at all those little OHs sticking up on the upper right picture,

we see that they're all on the same side of the molecule.

Whereas we look at the one below, we see the molecule is twisted and bent and

these OHs are on other sides of the molecule.

That's the difference.

It makes that component indigestible to mammalian digestive enzymes.

Now the interesting thing is, termites, cockroaches,

silverfish can digest cellulose.

And you have to wonder why in billions of years of evolution no

mammal adopted that method of digesting cellulose.

It would have been a tremendously advantageous for competition.

That's why we have herbivores though.

Herbivores have unique adaptions in their digestive gut

where they harbor bacteria that digest plants cell wall.

Plant carbohydrates are indigestible by humans and other monogastric,

but herbivores harbor these bacteria that digest cellulose.

And so feeds that we would not be able to consume are able to be consumed by

especially ruminants.

Cattle, buffalo, camels, sheep, goats, and other animals that have

these special adaptations in their gastrointestinal intestinal tract.

And so ruminants can utilize a lot of end products of food processing that we can't

utilize that are high in these plant fibers.

Now what do the ruminants use?

Well, the bacteria break down the cellulose to small,

organic compounds, what we call, volatile fatty acids.

They absorb that from the rumin, and they use that for energy.

In addition, in cattle and buffalo, they can utilize the bacteria that flow out

of the rumin as a high quality protein source.

So they can take low quality diets, convert them into high quality protein

diets, and make milk and make meat, in addition to other items.

So when we think about food systems, we really need to think about a food web.

Solar radiation comes down.

Plants are the primary autotrophs that capture that energy,

they produce cellulose.

Starch can be used by omnivores and monogastric animals.

Cellulose has to be digested through herbivores.

A small amount of use in omnivores.

But to get nutrients to flow through this system,

we need to have an interaction of different

types of digestive processes to have total flowed nutrients through this food web.

Then when waste material is excreted or animals die, microorganisms, bacteria and

fungi in the soil, break down those new transit that then become available to

the plant to continue to grow and produce new carbohydrates and other components.

And so, we need to think about the food system,

not in isolation, but as this network, as this web of relationships.

So bacteria and fungi break down the organic compounds.

The inorganic compounds, depending upon moisture and oxygen and other things,

and then that becomes available to the plant.

Lignin, which gives plants a great deal of rigidity, is a critical chemical

compound that limits the fact of how much cellulose can be digested over time.

And what gets trees such strong structure is they're highly lignified

compared to grasses that grow in their early vegetative state.

And they're very whimsy and wobbly.

Fungi are necessary to break down the lignin in

order to get that carbon from lignin back into the cycle.

And so we talk about this as being soil humus,

which is important to maintain soil fertility and health.

So the food production consists of a system of relationships,

which is necessary to cycle nutrients through the system.

There's an order to the food web.

Therefore there's an order we need to consider when we talk about human

nutrition and food.

Consumption and excretion define the relationships.

The production is enhanced by assisting and intervening at critical control points

called agriculture, that enhances the efficiency of what we grow.

Pollution and other disruptions are controlled by intervening at critical

control points that we call conservation to prevent unwanted leaching and

loss of soils into water systems.

The better job we at these critical control points, the better our yields and

the better we protect the environment

What About Livestock Systems? Part 1

Feeding the World

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