H. M. Briggs, of the Oklahoma Agricultural Experiment Station, compared the value of feeds by comparing lambs that he fed for uniform gains. He used corn and alfalfa hay as base feeds. The method, originally proposed by F. B. Morrison, of Cornell University, calls for the production of uniform gains in terms of uniform fat and protein storage, a condition that not all rations will produce. For example, oats and barley did not produce the finish in the carcasses produced by corn. Net energy values of 72.8 and 70.3 therms per 100 pounds were obtained with the technique employed for oats and barley, respectively, when those feeds replaced all the corn, and 80.1 and 64.5 therms when they replaced half the corn. Prairie hay gave a value of 33.8 therms per 100 pounds, and alfalfa hay gave a value of 41.5.

E. J. Underwood and four Australian associates, in studies of pregnancy disease in ewes, made observations on the levels of serum calcium, blood glucose, liver glycogen, blood ketone, and liver vitamin A in late pregnancy on poor and medium planes of nutrition. A rise was observed in ketone bodies in the cases of toxemia that occurred within 7 weeks of lambing. There were more cases among the poorly fed than among the well-fed ewes. There was no definite evidence of hypocalcemia, and glycogen reserves dropped. It seems that the disease is associated with, Or caused by, disturbed carbohydrate metabolism through low caloric intake and high demand. Prevention is achieved by feeding enough carbohydrate-rich feed to promote some increase in body weight. Other workers have reached the same conclusion; they recognize difficulties in diagnosis in some cases, but indicate that the disease is usually characterized by nervous symptoms, hypoglycemia, acetonemia, and fatty in- filtration of the liver.

Considerable adjustment has taken place in feeding protein concentrates and in expressing protein requirements for various classes of. animals. To meet the greatly increased demands of livestock feeders for protein feeds, the tonnage of soybean meal has increased considerably. Supplies of animal protein, however, were reduced by the curtailment in the production of fish meal and the diversion of milk byproducts to human consumption. A serious problem was thus created in changing the proportions of animal protein to plant protein that had to be used in diets. The change, of course, concerned mostly poultry and swine because they depend on the feed supply for the balance of essential amino acids most favorable for best performance.

Feeding experiments on growing and fattening pigs established that such animal protein supplements as tankage could be cut back to a level of about 3 percent of the diet by substituting properly heat-processed soybean meal. But calcium and other essential nutrients, otherwise supplied by the animal byproduct feeds, must be supplied from another source. Older pigs above 100 pounds and breeding stock can be fed successfully on rations lacking animal protein if care is taken to supply good green pasture or other good supplemental feeds, such as alfalfa. From a survey of available information, H. H. Mitchell, of Illinois, concluded that the value of protein supplements of animal origin, compared to those of plant origin, was not so much in superiority in amino acid make-up as in mineral and vitamin composition. This largely accounts for the need for a calcium supplement with soybean meal and the importance of green pasture and alfalfa hay for pigs fed all-plant diets.

How much total protein is needed by swine of varying sizes, particularly by pigs weighing 50 pounds or less? The table of daily allowances by the National Research Council gives an answer : The equivalent of approximately 22 percent of the total ration for 50-pound pigs. As weight goes up, the percentage drops, until at 200 pounds it is 13.3 percent.

Urea and other nonprotein nitrogen compounds, as substitutes for preformed proteins in the rations of ruminants, have been used most widely as ingredients of the concentrated mixtures fed to milking dairy cows. S. H. Work and associates found that urea can be fed fattening steers either on pasture or in dry lot at levels of 0.18 and 0.35 pound daily without causing damage to the kidneys and livers.

In experiments with yearling steers fed a basal ration of prairie hay, H. M. Briggs and others at the Oklahoma Agricultural Experiment Station found that urea made into pellets with hominy feed and molasses was as well utilized as cottonseed meal in terms of digestibility and storage of nitrogen. In fattening tests, a urea-containing mixture made to furnish the equivalent of 25-percent protein was considered better than a 50-percent formula and about equal to cottonseed meal. In some tests there was evidence of lowered palatability of the feed mixture because of the presence of urea, with consequent retardation in the rate of gain.

Tests conducted at the Illinois Agricultural Experiment Station with lambs showed good utilization of the urea as long as the level of total protein equivalent was kept on a medium plane of around 12 percent. The researchers conclude that lambs cannot utilize urea fast enough to meet their requirements for maximum growth. No evidence of kidney damage resulted even when the ration contained 3.16 percent of urea.

Results obtained by J. P. Willman, F. B. Morrison, and E. W. Klosterman at Cornell University on lambs fattened on a basal ration of yellow corn, corn silage, and hay showed that urea did not improve the rate of gain, as compared with the improvement obtained with linseed meal.

In seeking an explanation, J. K. Loosli and L. E. Harris tested the value of the amino acid, methionine, as an adjunct to the urea. The results, as measured in rates of gain and in nitrogen retention, showed that the methionine produced a decided improvement. The men suggest that the protein formed by micro-organisms from urea alone may be of inferior value, under certain conditions at least, but that the lack can be corrected by the methionine. Thus it seems evident that the use of urea in practical lamb-fattening rations requires further study to define the conditions under which the material can be depended upon to contribute the full value expected.