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NEli ENtLAND ASSOCIATION of CIEMISTRY TEACHERS
Calories E. G. RITZMAN New Hampshire Agricultural Experiment Station, Durham, New Hampshire
duced, due largely to the caloric losses in converting plant into animal tissue. Hence, under stress of general food shortage, man is usually forced to forego the meat in his diet and in its place to consume the cereals from which meat is ordinarily made. As a result, livestock meets with severe competition for its position as the chief consumer of cereals and as a main source of human food. Consequently the problems of animal nutrition assume quite a different physiological as well as economic aspect from those under normal conditions. We are now undergoing such a transition, and it seems advisable that research and practical nutrition should meet the new problems in their true economic light. The problem of livestock feeding during the last war involved these three vital aspects of the economic use of feed stuffs for the best national interests: (1) to maintain the livestock population a t as high a numerical level as possible; (2) to utilize substitutes for feeds no longer available; and (3) to curtail the feed intake whenever it could be done without physical damage or economic detriment. In other words, it is not a question of what can be dispensed with, but what can be dispensed with the longest without loss of efficiency. In the adult population the daily requirement for mineral matter, except for lactation, is exceedingly small, and most of the demand can be supplied (to livestock) in the ordinary forages, if grown under favorable conditions. Ordinary salt, of which the supply is plentiful, is about the only exception. The indispensability of vitamins as protective or regulatory factors is beyond question, but there is still much uncertainty as to their capacity for body storage as a reserve for future use. Protein, of course, forms one of the primary quantitative factors which supply material for growth and the solids of milk. It must be available daily in proportion to the demand, but recent inAbstract of an address presented at the Fourth Summer Conference, University of New Hampshire, August 14, 1942. The vestigations indicate that feed standards have tended address, which was written in the spring of 1942, has heen pub- to overestimate the amount of protein required for modlished in more completeform as Circular 62 of the New Hampshire erate performance in both of these functions, and the Agricultural Experiment Station, University of New Hampshire. daily demand of the nonlactating, but otherwise active, Durham, New Hampshire, June, 1942. 4110
HE GREATEST waste in the destructive process of war occurs in the loss of energy and energy-yielding substances. Energy is the driving force that impels the mechanical as well as the human element in the war machine. Both must be given first consideration in the effort to maintain the highest possible standards of efficiency. When the supply of calories becomes scarce, the general public must be the first to tighten its beit. In modern war economy the competition for potential human food is not only between the needs of the military and the civilian, but also between the human and the industrial. Huge amounts of fats, necessary for the manufacture of glycerin, are turned into explosives, and normal human food crops such as grain and potatoes are turned into alcohol, which is used for the same purpose. Food rationing for human consumption by government edict has again become a reality, and food rationing of another sort will no doubt come for livestock. World dependence on this country as a source of supply for food as well as for the munitions of war has already become urgent and will endure for a long time after peace negotiations start, so that food for both human consumption and for livestock may be below the "evernormal-granary" standard for perhaps a decade to come. While this country, even under war conditions, can readily produce an abundance of food for its own people and livestock, the unlimited demand put upon us to prevent starvation of masses abroad will make such inroads on our potential productive capacities that we shall need to plan the most economic use of food a t home. Emergency problems must be considered in the order of their immediate importance, and we can draw on our experience of World War I with profit. Animal products are a much more costly form of human food than the cereals from which they are pro-
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adult animal is exceedingly small. The demand for rected to these facts because they have been largely energy has always had first call in food requirements disregarded in nutrition investigations. during an emergency. The animal organism operates on enerRy, just as evemhing else that moves; as a P W S I O ~ G I C A LEFFECTS O F UNDERNUTRITION ON ADULTS consequence the daily demand may vary tremendously. It was known that the intensity of such vital activiA thorough knowledge of available food supplies and the ties as pulse rate, energy metabolism, glandular activphysiological ability of the person or animal to function ity, and the minor muscular or nervous manifestations as a machine under such altered nutritive conditions which in the general deportment of the animal are is imperative. A comparative survey of the amount marked by differences in alertness of spirit,'vary with of energy required (1) to maintain health when the the feed level. The immediate response by which an available food supply is below normal standards increase or decrease in some of these physiological (minimum safe margin), and (2) to maintain health functions follows quantitative changes in feed level was, and stamina to perform the normal daily tasks required. however, a surprise. Temperature. No significant difference in body UNDERNUTRITION temperature was observed in 14 steers subjected to Research has verified the empirical observation that tremendous variation in feed level. The skin temperaundernutrition in a balanced diet of requirements for tures of the control animals were, however, consistently growth results in a corresponding decrease or cessa- above those of the underfed animals, showing that tion of growth. There has been considerable research underfeeding may be assumed to have an influence in on the permanent effect of such lowered standards, modifying skin temperature. indicating that an inability to make up the loss is the Pulse Rate. During maintenance feeding of 14 exprimary consequence. That is, the animal body remains perimental steers, the average pulse rate ranged between stunted. The degree to which undernutrition causes 40 and 49 beats per minute. On submaintenance diets this injury is related to the age a t which i t occurs, in the animals showed a range of 25 to 37 beats per minute, other words, to growth rate. The effect is most pro- while during the fattening period, when heavy grain nounced a t birth. It decreases as the animal grows rations were given, they showed a range of 73 to 89 older. It has already been shown that animals which beats per minute. The immediate response by which are made to grow slowly by caloric restriction have a the speed of vital machinery is adjusted to changes in longer life than those which grow very rapidly under feed level was evident throughout the course of the exheavy feeding, but the lack of any one of the major periments. food factors in the very young cannot be continued Glandular Activity. Evidence of lessening in glandular secretion was noticeable on submaintenance diets. long without dire consequences. There is hardly a subject on which the public is so This was manifested by change in the tone of hair and misinformed as undernutrition. Undernutrition, as loss of flexibility of the skin. These changes came indicated by shrinkage of weight, or by a stationary about very gradually, being first apparent approxiweight below that which forms a normal proportion mately one month after submaintenance began. Conto frame dimensions, is nearly as common as mainte- trary to the expectation that they would greedily connance of surfeit feeding. Nevertheless, public opinion sume a moderate ration after having been undernourfails to distinguish in depee, visualizing i t usually in ished for four and one-half months, the animals ate slowly and with indifference when they again were fed terms of its extreme effect, stamation. Few people realize that the normal course of nutri- more liberally; in fact, approximately a week elapsed tion, as i t is imposed on animal life by nature, is a fluc- before they showed a desire or capacity to handle a tuating process. Periodic undernutrition is the rule maintenance ration. This was due, no doubt, to an rather than the exception. Animals have to be inadequate stimulus in secreting digestive fluids. equipped to meet such emergencies, or they would not Muscular Actierity. Daily observation showed that survive. Human beings and animals often lose con- on the whole the animals behaved much more quietly siderable weight, a loss which physiologically is seldom and inertly when undernourished than when on mainharmful, often is beneficial, and many times is eco- tenance. The greatest amount of nervous alertness omically imperative or unavoidable. Among wild and muscular flexion was manifested without excepanimals, particularly the herbivora, undernutrition tion when the heaviest grain rations were fed. comes as a regular periodical occurrence for four or five Energy Transformation. From the purely quantiwinter months. During the time they usually bear tative viewpoint, the current demand by the body is their young the drain is great, and yet wild animals are, far greater for energy than for any of the necessary comon the whole, as vigorous and thrifty as domestic stock, plex substances: proteins, mineral elements, and the since they attain a remarkable plumpness by grazing food accessories known as vitamins. There are two during the summer wheu feed is abundant. It seems possible ways by which the body can maintain its heat needless to enlarge here on the frequency with which when the energy income is cut below maintenance: by domestic animals on the farm and on the range show decreasing the rate of energy expenditure to meet the the marks of enforced submaintenance caused by ill- daily income, or by drawing on the body tissue to make balanced rations or droughts, but brief attention is di- up the deficiency when expenditure is not decreased.
However, all the evidence indicates that the body gives up its reserve tissue with great reluctance; while some body tissue was withdrawn to make up a food deficiency, the immediate effort was to cut down the demand for this draft on the body by curtailing muscular activity. The general agreement between behavior of pulse rate and rate of energy metabolism on undernutrition suggests the existence of a strong automatic impulse to protect the body against a severe drain on its tissue when the balance between income and outgo of energy is negative. The assumption that the enforced alterna-
tion in the standards of living of wild animals is the chief cause of their remarkable vitality and thrift when feed becomes abundant is borne out by the results of this experiment. Loss in Body Flesh. During maintenance, when the food protein was about adequate to supply the body requirements, the normal body turnover in daily wear and replacement of tissue was about five times as great as during the lowest level of undernutritioil, the economy in the latter case due mainly to a corresponding reduction in physical and vital activity.
