New Ideas in Feeding

by N. R. ELLIS

WE HAVE had to revamp many of our old ideas about feeding livestock. War proved again the tremendous importance of food. We had to get all the milk, eggs, poultry, meat, pork, lard, beef, veal, lamb, and mutton we could and make every tittle of grain count in doing so. Chicken was compared with hog and hog with steer to see which yielded the most nutrients for humans in return for the least feed. Egg was measured against pork and pork against beef to determine relative food values. A dozen questions were raised that we thought we had answered pretty well before—the best weight at which to market swine, for example, and the amount of grain to feed to fattening steers.

We discovered that an animal's increase in live weight or the total quantities of eggs and milk were not exact enough measures of relative efficiency in converting feedstuffs into foods for human use. We had to consider the separate nutrients, the vitamins, minerals, proteins, and energy values, because one animal product may represent a highly efficient production of protein, and another of fat. Besides, supplies of common feeds were often scant, and new types of feed and sometimes entirely new feeds or feed byproducts were introduced. Out of this situation came extensive changes in diets and rations for livestock. Some of them are transient reflections of the war, but many may be permanent.

Early in the war, committees of the National Research Council undertook to state the nutritive requirements of different classes of livestock on a basis comparable to those for humans. They used the best available information on all the known essential nutrients in arriving at the figures, which were set up as guideposts for the rationing of livestock and served as indices of the research requirements to confirm or modify our information on the exact needs for energy materials, proteins, mineral elements, and vitamin factors necessary for a given purpose. Of the standards thus summarized, the ones of concern here are for swine, cattle, and sheep.

The relative proportions of forages and of concentrated feeds that yield the greatest financial return on the farm and at the same time satisfy the market demands for quality in beef have been a debated subject for years.

The need to conserve corn and other grains and protein concentrates for other livestock or for direct human use focused attention on methods of fattening cattle during the past few years. Considerable experimental work has been done on systems of feeding that utilize a maximum of pasture and harvested forages. As an example of the savings in concentrated feeds that can be made, the North Carolina Agricultural Experiment Station, in cooperation with the Bureau of Animal Industry of the Department, fattened yearling steers on varying amounts of barley and lespedeza hay with, usually, a small allowance of protein concentrates. The limitation of the allowance of barley, with corresponding increases in hay, has permitted the production of carcasses grading somewhat below the Choice level, yet very satisfactory.

Actually, the limitation of the amount of barley to two-thirds that of the full-grain group got the best results in terms of savings of grain for grade of carcass produced. Such a limitation, whether in the dry lot or on pasture, promises to yield beef produced almost as efficiently in terms of units of concentrated feeds as is pork or poultry meat. Such a favorable comparison is not often possible where beef animals are fed all the concentrates they will consume readily. It is evident that with a moderate Y sacrifice in grade, whereby the marketed product is classed in the upper brackets of the Good or Choice grades rather than top Choice or Prime grades, beef can be produced about as efficiently, in terms of concentrated feeds, as other classes of meat animals. At the same time, increased dependence is placed on forage crops, whose quantity and quality have been greatly improved in recent years.

While the maximum use of roughage in the form of pasture and harvested forages has been stressed in feeding horses under farm conditions, the transportation and use of bulky feeds may sometimes pose serious problems. Early in the war a possibility that horses might be used overseas by our armies prompted a study of the problem. We found that we could reduce the amount of hay fed both idle and working animals providing the allowance of concentrate was increased to make up for the nutrients in the hay. The tests indicated that 4 pounds or so of hay per 1,000 pounds of animal weight were adequate, compared with the normal allowance of 10 pounds. Decreases in the roughage content of the ration, we learned, permitted more complete digestion of the feeds as a whole. This effect was accordingly reflected in the feed allowance required to maintain weight, and necessitated a reduction in the amount of total feed as calculated according to the usual standards.

A further development has been the making of pellets or briquettes out of mixtures of chopped roughage and concentrated feeds. Several European nations used briquettes in various forms as horse feeds during the war. In experiments at Beltsville, briquettes weighing 1 to 2 pounds were made of a mixture of four parts of chopped alfalfa or timothy hay, four parts of crushed or whole oats, one part of beet pulp, and varying amounts of a binder, such as corn dextrin.

C. P. McMeekan and two colleagues in New Zealand applied to lambs a three-level system of feeding like the one McMeekan used some years ago in swine feeding. When lambs were fed at low, medium, and high planes to weights of 28.4, 38.2, and 49.6 pounds, respectively, there was little effect on skeletal growth. Muscle growth was moderately retarded when the level of feeding was lowered. Subsequent feeding on a high plane promoted rapid recovery in the low and medium groups, but the lambs never caught up with those in the high-plane group. The greatest recovery in comparative terms was in fat deposition.