By ANN HINCH
Assistant Editor

ST. LOUIS, Mo. — Working in an agricultural job is not necessarily indicative of an agrarian background – and even those who did grow up on a farm may not know everything they need to about their new ag-related job.

This is why the American Feed Industry Assoc. (AFIA) hosts a Feed Industry Institute every two years. Last week was the first time the institute had moved out of Chicago in its 30-year history, taking place instead in downtown St. Louis.

Approximately 125 “students” and “professors” attended the June 14-17 workshop, which consisted of nearly 30 sessions, 30-60 minutes each, focusing on livestock physiology and nutrition.
Professors are feed industry experts and veterans from around the country; students are those workers in AFIA-member feed mills and related businesses whom their employers deem it beneficial to attend the institute.

“Individuals who are relatively new to the industry tend to get the most out of it,” explained Anne Keller, AFIA communications director, but she said the organization has heard from more experienced employees, as well, that they learn new things.

In 1980, the National Feed Ingredients Assoc. planned its first Feed Ingredient Institute, the name it kept until just a few years ago. When that organization merged with the AFIA in 1992, according to Keller, the institute was kept. It is held in even-numbered years.
While the institute obviously must keep up with technological advances, each time it keeps the same basic framework, Keller said: “For example, there’s always a course about vitamins, and there’s always a course about legislative and regulatory issues.”
Digestion basics

Each session during this four-day workshop builds upon knowledge in previous sessions. The first course went over the basics of ruminant and non-ruminant physiology and anatomy, which is vital to anyone manufacturing or selling livestock or pet feed.

Dr. Aaron Gaines, vice president of Production Resources & Operations for The Maschhoffs in Carlyle, Ill., and Dr. Matt Gibson, vice president of Feed for ICM, Inc. of Wichita, Kan., led this opening course. Gaines explained there are six basic nutrients all animals need to survive: water, proteins, carbohydrates, fat, minerals and vitamins.

The difference between non-ruminants and ruminants is in how their bodies metabolize nutrition. A non-ruminant, or monogastric, animal has a single-compartment stomach, whereas a ruminant has a compartmentalized stomach – “It’s one stomach with multi-compartments, not four stomachs,” Gibson emphasized. “Although there is a forestomach.”

A monogastric cannot digest fibrous feeds – except for the horse and the rabbit, both of which have a large cecum and colon for the fermentation of fibrous foods such as hay and grass. These two animals are called pseudo-ruminants.

A ruminant’s stomach ferments its food, and such animals – such as cows – produce saliva continuously to help break down feed, whereas a monogastric (such as a pig) produces saliva only when needed and has enzymes to break down food.

Gaines explained the pig is often used to study and explain monogastric digestion since its system is very close to a human’s. Most nutrients are absorbed into the body through the wall of the small intestine and liver, after food has been broken down in the stomach.

The remaining materials pass into the large intestine, which helps the body reabsorb water from digestion, and bacterial fermentation of fiber takes place into vitamins and fatty acids the body can use, before the system passes the rest out as waste.

Enzymes in the mouth and esophagus break carbohydrates – starch – down into glucose, a simple sugar, before food gets to the stomach. There, proteins are broken down into peptides for amino acids, which the body can then use. Further breakdown of starch into glucose takes place in the small intestine.

Chickens and other poultry, who are also monogastrics, have a slightly different system. For one, there are no teeth to break down food, though their beaks do some of this. The esophagus, or crop, is an enlarged area for digestion of starch.

Poultry have a gizzard for breaking food down further – if you see a chicken pecking at gravel or grit, that goes into the gizzard to grind feed. Poultry also lack lactase, which is necessary to break down lactose, or milk sugar, into glucose.

“If you can understand (the gastrointestinal tract), then you can correctly identify an animal’s needs with respect to nutrition,” Gaines told the students.

Gibson said a ruminant’s stomach differs from a monogastric’s not only in function, but in size. “These things are giant inside these animals,” he said, indicating on a diagram how much of a cow’s body its stomach takes up.

When a ruminant regurgitates cud to chew, it’s not the same as vomiting (in fact, if a ruminant is actually vomiting, it’s a bad sign, according to Gibson); the purpose is to further break down roughage so it can pass through all the stomach’s compartments. Gibson said this is an evolutionary holdover that allowed ruminants – often prey – to forage in the morning, then hide safely and spend the rest of the day chewing, reducing and digesting food.
The second stomach compartment is the rumen, the animal’s primary fermentation vat, where carbohydrates are broken down by bacteria, protozoa and fungi. A high-grain diet, Gibson said, cuts down on the latter two types of microbes, and tends to reduce milk fat.

A dairy cow on forage will produce more acetic acid for milk fat, he added, whereas highly-grain-fed beef steers are hardly called upon to produce milk. Pharmaceuticals can also affect milk fat levels, he said.

Gibson cautioned against always relying on physiological models without question, since there may be exceptions. For example, he said there are dairy producers who feed their cows distillers dried grains (DDGs), and their milk fat is not going down.

Another exception with respect to the ruminant digestive system are young animals, such as calves, which are effectively non-ruminants until they are fully weaned from their mothers. An unweaned animal’s esophagus bypasses the first two compartments of the stomach in order to preserve milk proteins important to growth.