Nutrition and its Importance in our Modern Agriculture

What is nutrition? A dictionary such as Webster’s may define nutrition as “being nourished” or “The series of processes by which an organism takes in and assimilates food for promoting growth and replacing worn or injured tissue.” These are obviously, very simplified definitions. Nutrition today, as practiced by competent professionals, requires that the nutritionist be knowledgeable with respect not only to the nutrients, their function, occurrence and so forth, but also with animal behavior and management, digestive physiology, and some aspect of biochemistry and analytical chemistry. In addition, knowledge is required in the fields of crop and soil science, endocrinology, bacteriology, genetics, and disease as related to nutrient needs and dietary requirements.

The old adage, “a little knowledge is dangerous, “still applies to the study of nutrition.

In the author’s (Church) opinion, a competent nutritionist must be able to formulate diets, rations, or supplemental feeds that are sufficiently appetizing to insure an intake (not necessarily maximal) adequate for the purposes desired. He must nearly always take into account the cost of the supplemental or total mixture, and formulated rations should supply adequate nutrients without detrimental imbalances for the desired level of production and take into account the need and required level of growth promotants, medicants, or other nonnutritive additives. In addition, the rations so formulated must have adequate milling, mixing, handling, and storage properties. A nutritionist may be called on to know or to do numerous other things, but these functions would seem to be the minimum that should be expected.

1. Genetic Improvement Improvement in the genetic potential of animals in recent decades by selection, crossbreeding, development of hybrid lines of chickens, and the use of high quality sires in bull studs has brought about a general improvement in the genetic capabilities of domestic animals and, where the environment is suitable, an increase in productivity. The increased rate of growth one might expect from a well-bred broiler chick, however, requires a higher quality diet to supply the needed nutrients.

2. Improved Health and Management The availability of antibiotics and other drugs in recent years has allowed many diseases to be kept under adequate control. Likewise, vaccines of various types have been developed with which animals may be immunized against many diseases. Accompanying these changes has been a gradual development and appreciation for management techniques and procedures which may result

in more efficient means of handling and managing animals. the overall result is that a greater productivity may be expected along with more critical nutrient needs.

3. Development of Large Specialized Operations The broiler and egg industries are two excellent examples where a tremendous growth in large, specialized operations has occurred in which thousands or even millions of birds are managed in one large operations. These large unit depend upon a relatively high productivity/bird, and efficient utilization of feedstuffs is a must when the product sold is very cheap. Furthermore, the birds are usually completely confined so that all essential nutrients must be available and the feeds must be palatable and readily consumed to achieve rapid growth rates or high egg production.

4. Greater Stresses on Animals Several factors may contribute to greater stressing effects on animals in today’s agriculture. Of these, the movement of animals throughout the world by ships, air, and ground transportation may result in very rapid dissemination of disease organisms and their vectors. Close confinement of large numbers of animals is more apt to result in disease outbreaks. In addition, the close confinement must, in many instances, result in psychological and sociological stresses that have unknown effects on animals performance and nutrient requirements.

The process of assembling large numbers of animals from diverse backgrounds (this applies particularly to cattle and sheep) must result in a variety of stresses. Animals may be transported over long distances in adverse weather. Their previous exposure to disease and parasites differs, and sudden confinement with strangers is another adverse factor. Many range cattle or sheep have never consumed any feed but forage, and suddenly they are confronted with strange surroundings, strange feed in bunks, water in containers, and are subjected to loud and totally unfamiliar noises. The stress of weaning may also be imposed on top of these other stresses.

In many of the large beef feedlots it is the practice to dehorn and castrate where required, brand, inoculate for a variety of diseases, administer vitamins of various kinds and, perhaps, treat for stomach worms or other parasites in one quick trip through the squeeze chute — all this being done to an animal that probably has not recovered from stresses to which it has previously been exposed. If nothing else, the ability of cattle to withstand such a combination of stresses convinces one that they are extremely hardly animals. Furthermore, most of them recover and do surprisingly well in subsequent months in the feedlot. Death losses,

as a whole, are remarkably low in well-run feedlots. Thus, the important role of adequate nutrition for animals subjected to such stresses in current commercial practice seems clear.

5. Economic Pressure to Increase Crop Production Agricultural production of various crops faces the same type of cost-price squeeze that applies to the animal industries. One solution to this problem is the application of increasing amounts of fertilizers and of cultural or management practices that serve to increase yields. One possible result of the increased yields is the production of plant tissues that may be deficient in one or more of the mineral elements, particularly the trace elements.

Fertilization under some conditions may result in toxicities, as well. One example is in the heavy use of N fertilizers, particularly on soils borderline of deficient in sulfur. The plant tends to accumulate much higher levels than normal of nonprotein amino acid N as well as nitrate-N. Plants grown under this conditions can easily accumulate enough nitrate-N to be toxic. A second illustration applies to acid soils where either Mo or Ca will result in increased production of legumes. Mo applications may be used without markedly increasing plant tissue levels or at least not to an objectionable level. When both Ca and Mo are applied, however, the plant may accumulate toxic quantities of Mo. This would, of course, reduce performance of animals consuming such forage in quantity.

These examples clearly illustrate some of the problems that can occur as a result of nutrient imbalance in the soil, although the frequency of occurrence is poorly documented. Undoubtedly, many other analogous but unknown situations occur from time to time but are not recognized at this time. The incidence of such situations will increase with time unless remedial measures are taken.

6. Increasing Use of Waste and By-Product Feedstuffs Many animal producers are increasingly turning to the use of any apparently useful product which is competitively priced that the animal will consume without apparent harm in an effort to hold down the cost of production. Materials having potential value for feed include garbage, sewage, poultry litters, manures, papers, wood, and bark products. Currently, several experiment stations are vigorously working on the utilization of poultry and ruminant manures which are beginning to present disposal problems in some heavily populated areas. Numerous papers have appeared in recent years dealing with use of wood products and paper, and others on garbage, sewage sludge, and crop residues. Currently there is a great deal of interest world-wide

in improving the utilization of low-quality roughage and straw. More of this type of information may be expected in the future.

7. Increasing Use of Synthetic and Purified Products There has been a tremendous increase in the usage of urea over the past 20 years in ruminant rations. Although this has often resulted in a reduced cost of crude protein in the formula, it has not always resulted in efficient utilization of the needed N because of limiting factors such as readily available carbohydrates or to any of several required mineral elements. Inappropriate use as often resulted in toxicity, as well. There is no reason to believe, however, that usage will not increase, but this will require, again, competent nutritional wisdom to take advantage of the lower cost of N from such products. There has been much interest recently, in the use of methionine hydroxy analogue in ruminant rations because a limited amount of work indicates that methionine (an amino acid) may be limiting, particularly for high-producing dairy cows. Other examples of this type may be expected to come up from time to time in the future.

8. Individual Variation in Nutrient Requirements Examples of variations in nutrient requirements that may be seen in laboratory animals and man have been well documented and discussed by Williams (1,2). These examples clearly show that a wide range in requirements for a variety of different nutrients may be expected, sometimes in even closely inbred strains of laboratory rats. Obviously, this variable presents great problems in the field of human nutrition, requiring the development and dissemination of needed information on this subject and more training in nutrition of people in the medical field. With domestic animals, except for pets, the common practice would be to cull animals that do not perform adequately, whether the cause be an excessive requirements for nutrients or for other reasons. The incidence of occurrence of domestic animals with very high (or low) nutrient requirements is poorly documented at this time, but is a subject that is certainly worthy of further study.

References Cited1. Williams, R.J. 1956. Biochemical Individuality: The

Basis for the Genetotrophic Concept. Wiley Pub. Co., New York.

2. Williams, R.J. 1971. Nutrition Againts Disease. Pitman Pub. Corp., New York.