A classification in humans has been typically by food groups.
We talk about fruits, vegetables, dairy products, meats, and so forth.
And we have the food pyramid that recommended
what should be consumed within each food group each day.
For animals though we still base on source, roughage versus concentrate.
But we also classify them based on nutrient content.
What's the protein content?
What's the fiber content?
And also further we base them on purpose.
Is it a mineral supplement, a vitamin supplement or a feed additive?
The description of feeds, the NRC,
the National Research Council compiles feed libraries for
each domestic animal species based on nutrient content of the feed ingredient.
And they publish this and
update usually every eight to ten years based on a committee work.
And the publication covers many different animal species.
Dogs, cats, sheep, goats, beef cattle, dairy cattle, laboratory animals, rabbits.
And so you can look up within each of those publications what the feed
analysis is, the nutrient content is, for the feeds used within those species.
Also, there's a description based on the type of feed offered.
And so for our pets, we're used to having canned food or semi moist or dry foods.
However we can also talk about if you're purchasing feed, a sweet feed,
a crumble, a flake, for fish they'll be seeking and floating feeds.
And also for a dairy herd, we talk about a total mixed diet, a total mixed ration,
a TMR, where all their feeds are mixed together.
The NRC classification for livestock is based on eight categories.
We talk about roughages, which are sub broken into three groups.
Pastures, dry forages, and silages.
And then concentrate supplements, protein supplements, mineral supplements,
vitamin supplements, and nonnutritive additives.
Nonnutritives additives would be things like coloring agents,
flavorings, factors that help us bind things together in a pellet.
And also antioxidant factors that are added to feeds.
And then there'll be subclasses within feeds based on processing.
And so complete feeds we may talk about as in pet foods, canned foods,
dry foods, semi-moist foods, kibbles, crumbles and mash.
However, within also livestock feeds we can talk about flake feeds.
Just like we have corn flakes, we have flaked corn that could be fed to animals.
We have ground corn, so we have ground feeds.
We have rolled feeds like rolled oats.
And we also have extruded feeds, and extrusion refers to a process by which
a feed ingredient is placed under pressure through a bore and
those feed particles then become expanded.
Almost like a popcorn, although not quite the same method.
When we look worldwide at what types of feeds are produced by the feed industry.
We see that poultry, the number one group that receives feed from the feed industry
followed by swine, ruminants, aquaculture or fish, and then pets and horses.
And you can see that there is quite a decline as we move from
poultry feed in millions of tons, metric tons being fed down to equine.
If we look at the total feed mills in the world, that feed animals.
This is data compiled by Alltech in 2014.
They could identify 26,240 feed mills throughout the world.
China, had the most feed mills in the world, followed by the United States and
then by Brazil.
When we look at what goes into animal feed, you may have difficulty seeing this
slide but the point is that many different products go into animal feeds.
And the largest product that goes in are cereals.
About 34% of the world production of cereals are used for animal feed and
of that, corn is the major cereal crop that goes into animal feed.
But you can also see in this slide things like vegetables, fruits, milk,
other oil crops and various things, many of these things come out of
the food processing industry as residues and they end up in animal feed.
And about 13% of total amount of things produced for
food are used for animal feed.
Some are edible for humans but most are processes
of things that get rejected out of the food distribution system.
An important thing when we look at feed stuffs is that we have to
analyze what the nutrient content is.
And that's typically done by chemical analysis.
It's a quantitative analysis.
It degrades feeds by a reagent digestion or by extraction with strong solvents.
And then we measure the components that are in that feed.
A relatively new method, although probably not so new now over the last 30 years,
has been to use infrared analysis.
Where the feed is heated and
an infrared spectrum is used to quantitative what's in the feed.
An infrared analysis needs to be calibrated against a chemical analysis for
each feed ingredient.
And then there are biological methods that can be both qualitative and quantitative.
A laboratory animal response to a feed.
Bacterial digestion of a feed.
Enzymatic digestion and then in sacco and in vitro.
These refer to where we would take feed, grind it,
put it in a porous dacron bag and then we can hang it.
Put it in the rumen of this cow shown here, with a fistula on her side.
Where that feed can be put into the rumen, and
we can understand how it will be digested and degraded in the rumen.
Also small dacron bags can be used to put in the digestive tract of horses or
pigs or whatever, and
those bags will flow down through the intestinal tract, be collected in feces.
Then we can see how things are being digested within the animal.
The standard analytical method is defined by the Association of
Official Agricultural Chemists, so the AOAC.
It was organized by the USDA in 1884.
Its headquarters are in Rockville, Maryland.
And now it has become an international organization.
And they publish approved methods for
feed nutrient analysis and these are constantly being updated and added to.
But if a feed laboratory is going to begin analyzing feed,
they really need to use approved AOAC methods.
What happens in nutrient classification, the food or
feed is taken and at first it is dried, water is measured within the feed.
And then dry matter is analyzed for organic matter and inorganic matter or
the mineral content.
And in the organic matter, we have carbohydrates, starches, fibers, and
sugars.
We have lipids, fatty acids, and other pigments.
We have proteins, which are composed of essential and none essential amino acids,
and then vitamins.
And then some other sub components, like nucleic acids,
and some other components that would be in your organic matter.
Dr. David GalliganProfessor of Animal Health Economics
James FergusonProfessor of Nutrition
