Nutrition

By Francis H. Kallfelz.

Some of our most nutritious foods come from cattle. Beef and dairy cattle are the source of hamburger, steak, milk and cheese, to name a few. Such foods are very important for human growth and health.

To insure a plentiful supply of these foods, it is of course necessary to provide optimal feed for both beef and dairy cattle so they will grow, reproduce, produce milk, etc., for the benefit of mankind. Much research has been and continues to be done to determine the best way to feed both beef and dairy cattle in order to produce food for humans.

Cattle as well as sheep, goats and deer belong to a group of animals known as ruminants. These animals have a digestive tract quite different from that of people, dogs, pigs and most other animals. A major difference is that the ruminant has four stomachs instead of one.

When a cow eats, the food swallowed enters the first stomach or rumen which is the largest of the four, containing in the adult cow a volume of some 30 gallons of mixed water and food.

The rumen is connected to the second stomach, the reticulum, and contents of the rumen can move freely into the reticulum and back again, through a large opening.

Forages (such as hay or silage) which are eaten by the cow remain in the rumenoreticulum for a considerable time period. During this time, the huge population of microorganisms present in the rumenoreticulum break down the fibrous portions of forages into smaller substances that can be absorbed and used by the cow for growth, milk production, etc.

Besides breaking down the fiber, the micro-organisms in the rumen also synthesize (make) other substances such as protein and vitamins which subsequently can be absorbed and used by the cow.

Mixing It Up

The first two stomachs undergo periodic contractions (every minute or so) which help to mix the food particles with the micro-organisms present. Cows also chew their cuds or ruminate. By this is meant that small portions of the food present in the rumen are periodically brought back to the mouth for further chewing and then reswallowed. This tends to further reduce the size of food particles so that they can be more easily broken down chemically by the rumen micro-organisms.

After leaving the rumen and reticulum, the food passes through a very small tunnel into the third stomach, or omasum. This stomach is round and about the size of a volleyball. Here it is thought that water is removed from the food. The food then moves through another small tunnel into the fourth stomach, the abomasum, which is similar to the stomach of humans and non-ruminant animals.

In the abomasum, food which was eaten but not acted upon by the micro-organisms in the rumen, substances made by the micro-organisms as well as some of the microorganisms themselves begin to be digested and made ready for absorption in the small intestine.

While some very small chemical substances can be absorbed through the rumen wall, most absorption of broken down food occurs in the small intestine of the cow as is the case in other animals. The absorbed food is then used for such things as energy, growth, and milk production.

Because cows have rumens containing micro-organisms capable of breaking down fiber (the woody parts of plants), they can digest inexpensive feedstuffs like grass, hay and cornstalks which cannot be digested by other animals and convert them into foods (meat, milk) which can be used by humans. The goal of cattle farmers is to obtain inexpensive feedstuffs which provide a complete and balanced diet for their cattle in order to produce meat and milk which can be sold for a profit.

Feedstuffs for cattle include forages, concentrates, and supplements.

Forages consist of grasses, legumes, hay, corn silage, and other substances which have relatively high levels of fiber. While historically these were sufficient to supply all the needs of cattle in the wild, modern day cattle have been genetically selected for high production. Forages alone are often incapable of providing the nutrient needs of these super-efficient "food factories" since the digestibility of forages frequently is quite low.

Thus more concentrated types of feeds must also be fed in most contemporary cattle operations. The term concentrate really means a feed which contains more available energy per pound than is found in forages. Grains such as corn, wheat, and oats are used as concentrates.

Rations of high-producing cattle often must be supplemented as well with protein, minerals, and vitamins. Feeds such as soybeans, cottonseed, and corn gluten can be used to provide extra protein and often are included in the concentrate portion of cattle rations. Supplements containing minerals and vitamins also are frequently added to concentrates when additional amounts of these substances are needed.

The specific nutrients of ruminants, including cattle, are similar to those of other animals. Since the rumen micro-organisms can manufacture many of these nutrients, however, the rations fed depend upon the nutrient requirements of the rumen micro-organisms as well as those of the cow. Also, nutrient requirements differ with age (young as compared to adult animals), product (milk as compared to meat), level of production (high producing as compared to average dairy cows), pregnancy, and so forth.

The nutrient requirements of adult beef cattle are not too high. Good quality grass pasture or grass hay in sufficient quantity is sufficient to supply adequate levels of protein, energy, fiber, and Most minerals for both pregnant and lactating beef cows.

Water, Salt

It is essential that clean water be available at all times. This sometimes can be a problem With cows on pasture during the winter when water sources may freeze. Also, trace mineralized salt should be available. If pasture or hay quality is poor, then supplementation with protein, energy, minerals, and vitamins may be needed.

Nutrient requirements of non-producing and pregnant dairy cows are similar to those of beef cattle. These animals can obtain all nutrient needs from a good quality hay, trace mineralized salt, and water.

The high producing milking dairy cow, however, has greatly increased nutrient needs. A cow producing 90 to 100 pounds of milk per day may require over five times as much protein and several times as much energy and minerals as a non-producing cow. While the lactating cow will eat more, it also is necessary to increase the concentration of protein, energy and minerals in the ration of these animals in order to provide adequate nutrient intake.

Concentrates play an important role in supplying the significant additional nutrient needs of the lactating dairy cow. A constant availability of salt and clean water also is essential. Lactating cows can require over 40 gallons of water a day.