In recent years unexpected deficiencies have appeared in swine fed on rations ordinarily considered adequate. For example, B. W. Fairbanks and associates at the Illinois Agricultural Experiment Station, while engaged in a study of protein requirements of pigs, observed poor growth, diarrhea, dermatitis, and other abnormalities on a ration of yellow corn, beef meal, soybean meal, alfalfa meal, and salt. A supplement of hulled oats was beneficial, but dry skim milk and dried corn distillers' solubles were not. Likewise, pigs fed a mixture of yellow corn, wheat flour middlings, soybean meal, fishmeal, tankage, minerals, and fortified cod-liver oil were benefited by the use of either a combination of B vitamins, dried corn distillers' solubles, or alfalfa meal. It was not possible to decide whether a new factor .was supplied in the feeds, or whether the trouble was in a disturbance in the supply of the known vitamins.

The corrective value of alfalfa for the feeding of sow pigs has been stressed by O. B. Ross and associates at the Wisconsin Experiment Station. With only 5 percent of alfalfa meal present in a basal mixture of yellow corn, soybean meal, and minerals, the gilts farrowed pigs, many of which had congenital malformations of the feet and legs. During the suckling period, the surviving pigs were not very thrifty, and showed various abnormalities in locomotion and in condition of skin and hair. These disorders were eliminated by the use of 15 percent of alfalfa meal in the diet. Others have also attested to the high value of alfalfa meal as a corrective feed for gestation and lactation; some scientists used a basic ration of yellow corn, soybean oil meal, fishmeal, tankage, minerals, and cod-liver oil. As measured by condition and numbers of live pigs farrowed, alfalfa meal, along with dried corn distillers' solubles, and a mixture of the six better known B vitamins were effective in varying degrees as supplements to the basal diet, but alfalfa meal seemed the most reliable.

A troublesome disorder in young lambs known as stiff-lamb disease, which has baffled investigators for many years, appears to be of nutritional origin. The addition of wheat bran or wheat germ had a striking effect in preventing the disease. Proof that vitamin E is the factor required was obtained when six out of seven stiff lambs responded to treatment with an alphatocopherol compound.

Nutritional studies applicable to horses have been conducted by a number of scientists, including P. B. Pearson and associates of the Texas station. They have concluded from experiments with Shetland ponies that both riboflavin and pantothenic acid are essential factors. On the other hand, nicotinic acid is synthesized in the body. Without riboflavin, the appetites and growth of growing ponies were poor. Estimates of the requirements for adequate nutrition indicate a figure of approximately 20 milligrams per 1,000 pounds of weight.

Evidence that riboflavin deficiency is accompanied by cataract formation and other related degenerative changes in the eye in various animals and also the involvement of ascorbic acid in the nutrition of the eye tissues prompted T. C. Jones, F. D. Maurer, and T. O. Roby, of the Army Veterinary Corps, to study the disorder in horses known as periodic ophthalmia. They noted a strong similarity between the pathological changes in experimental riboflavin deficiency in experimental animals and those in periodic ophthalmia. While the ascorbic acid content of the ocular tissues has shown a decrease, the men suggest that low riboflavin intake may be the primary factor.

This idea is supported by the results of feeding crystalline riboflavin to horses at the Front Royal Remount Station. Among a total of 130 horses that were fed 40 milligrams a day of this vitamin, none developed periodic ophthalmia in contrast to the usual rate of 109 cases per thousand untreated animals. Supporting evidence from other sources has not been obtained thus far, but the results are striking enough to merit further careful study. It should be emphasized that the experiments have dealt with prevention; there is no published evidence to indicate that the disease can be cured once it has developed in an animal.

THE AUTHOR

N. R. Ellis is a chemist in charge of animal nutrition investigations in the Bureau of Animal Industry. His research has included the biochemistry of animal fats, swine nutrition, and vitamin requirements of animals. He is a graduate of the University Of Wisconsin.