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IN THEIR studies with methionine-deficient broiler diets which contained 20 to 22% protein, Baldini and Rosenberg (1955) observed that the methionine requirement, expressed as percent of diet, increased as the energy content of the diet increased. It was predicted that this principle of the energy-dependence of amino acid needs would apply to all essential amino acids and for most animals. In the meantime this has been shown to be true for the lysine requirement of rats (Rosenberg and Culik, 1955) and for the methionine requirement of the turkey poult (unpublished). In view of the realization that the energy content of the diet has such a pronounced effect on amino acid requirements it became desirable to reinvestigate several other phases of amino acid utilization. In this communication we report some results of our studies on the effect which a change in protein level may have on the methionine requirement of broilers.

1. 1. Administration of α-lipoic acid to guinea pigs on a scorbutogenic diet appeared to afford about the same protection as a suboptimal amount of ascorbic acid. When small amounts of ascorbic acid and of α-lipoic acid were given, the combination protected the guinea pigs better than either compound alone. 2. 2. Male and female rats reared since weaning on a diet low in vitamin E did not reproduce. Administration of α-lipoic acid brought about reproduction although not to the same extent as that attained by an optimal amount of α-tocopherol. The offspring, maintained on the α-lipoic acid-supplemented, vitamin E-low diet, reproduced and weaned successfully a third generation. 3. 3. The efficacy of α-lipoic acid in alleviating symptoms of ascorbic acid and of tocopherol deficiencies can best be explained on the basis of a protective action exerted by α-lipoic acid or its dihydro derivative on the two vitamins.

CONSIDERABLE attention has recently been paid to the beneficial effects observed when fat is added to broiler diets. Slinger et al. (1952) and Siedler et al. (1953) studied the effects of fat in poultry rations. Sunde (1954) and Runnels (1955) called particular attention to the valuable increase in feed efficiency attained by the addition of fat to poultry feeds. The use of supplemental dl -methionine and the beneficial effects in growth and in efficiency of feed utilization obtained with practical chick starter and broiler diets are also well known from the work of Bird et al. (1945), Gerry et al.(1948), Saxena and McGinnis (1952), Matterson et al. (1953) and many others. In view of the rapid acceptance of nonfood animal fats in poultry feeds, a study of the combined effect of fat and dl -methionine as supplements in broiler rations was undertaken. Investigation of this problem has been in progress at the …

RECENT reports (Matterson et al., 1953; Menge et al., 1953; and Saxena and McGinnis, 1952) have shown supplemental synthetic DL-methionine to be of value in practical broiler diets. The basal diets in each case appeared to be borderline in their content of the sulfur-bearing amino acids, methionine and cystine, according to National Research Council allowances (1950) or to the more recent data of Almquist (1952). It has always been assumed that methionine will produce a beneficial effect only when added to a diet deficient in the sulfur-bearing amino acids. It was of interest, then, to test the effect of supplemental DL-methionine in diets containing adequate amounts of methionine in the natural, bound form, especially since previous observations from this laboratory indicated that free DL-methionine in broiler diets might have some unique, beneficial effect. This paper reports two experiments in which the effect of DL-methionine was tested as a supplement to …

THE nutrient requirements of animals are ordinarily expressed as percent of diet. Baldini and Rosenberg (1955) reported that the methionine requirement of the chick expressed in this manner was not a constant but varied with the energy content of the diet. They postulated that such a relationship probably existed with other animals and other nutrients. Such was found to be the case with the lysine requirement of the rat (Rosenberg and Culik, 1955). The experiments reported in this paper were conducted to determine whether or not a similar relation existed for the turkey poult. EXPERIMENTAL PROCEDURE This report summarizes the results of nine battery experiments, each of which employed ten treatments applied to duplicate groups of twelve day-old tom poults. Jersey Buffs were used in four experiments and Broad Breasted Bronze were used in five experiments. The length of each experiment was six weeks during which time weekly measurements of . . .

1. 1. The preen glands ( glandula uropygialis ) of ducks, geese, and chickens were examined for provitamin D content. No evidence for the occurrence of the provitamin was found. Therefore, the theory that birds obtain their vitamin D through preening no longer can be supported. 2. 2. A study of the distribution of provitamin D in the body of chickens revealed a high concentration in the sterols of the feet. 3. 3. A sample of provitamin D from chicken feet was converted by ultraviolet light into vitamin D. Biological evaluation of this vitamin indicated a high activity for chicks, approximately equal to the activity of vitamin D 3 . It is, therefore, concluded that the natural provitamin D of birds is either 7-dehydrocholesterol or a sterol of very similar structure.

The addition of increasing amounts of lysine to a diet of dried bread supplemented with fat, salts, and vitamins brought about significant growth responses in weanling rats. For example, a supplement of 0.5% dl -lysine·HCl, corresponding to 0.2% l -lysine, to a bread diet improved the average gain in weight after 5 weeks from 32% to about 75% of the average gain on the stock diet. An equal response is obtained from lysine added to flour before baking or from lysine added in corresponding amounts to the bread diet. At the end of 6 months the diet containing the supplement of 0.2% lysine had produced rats that were practically equal in weight to those receiving diets with larger additions of lysine. The animals on the basal bread diet did not attain weights comparable with those receiving the lysine supplements. If sufficient lysine was added to bring the total l -lysine content of the diet to about 0.8%, or more, a growth response similar to that obtained with the stock diet was observed. These results suggest that, so far as rat growth is concerned, the only important amino acid deficiency in commercial bread is lysine.

THE conservation of protein must be carefully considered in a world with a constantly and rapidly increasing population and an ever-dwindling area of farmland. A good method to conserve protein is to increase the efficiency of that which is used by animals in producing human food. This may be accomplished by feeding only the absolutely essential amount of natural protein and supplementing it with small amounts of materials that allow for the most efficient protein utilization. Probably the first to demonstrate this principle was Voltz (1919), who used synthetic nitrogenous materials to supplement the protein fed to ruminants. More closely allied, perhaps, with the subject of this paper is the work done with the quail (Baldini, 1951). It was found that the quail, which is normally said to require 28 percent protein in its diet (Norris, 1935; Nestler et al., 1942; Stadelman et al., 1945; Baldini et al., 1950), could …

THE addition of fat to broiler diets has resulted in various observations from different laboratories. Siedler and Schweigert (1953), Runnels (1955), Sunde (1954) and Biely and March (1954) have reported that fat favorably influences feed conversion and growth of chicks. Rosenberg et al. (1955) gave an account of the manner in which fat increased the amino acid requirement of the chick, and Combs (1955) reported on the part fat plays in body composition of chicks and tendency of chicks to “overeat.” The question naturally arises as to whether these beneficial effects are due entirely to the energy content of fat or to some other intrinsic value of fat per se. The experiments presented in this paper were designed to shed light on this question. EXPERIMENTAL PROCEDURE Two four-week experiments are reported in which three and six replicate groups of 16 battery reared New Hampshire male chicks were used in each …

Samples of corbisterol acetate and 7-dehydrocholesterol acetate were saponified and the free sterols irradiated with ultraviolet light. Rat assays showed the two preparations to have about equal antirachitic potencies. Chick assays of the irradiated corbisterol indicated a ratio of rat to chick efficacy of about 100:4.

The nutritional effect which may be obtained by the addition of lysine, methionine, valine and threonine to a diet composed of commercial white bread, fat, salts, and vitamins has been investigated with weanling rats. A beneficial effect could be observed only from the addition of lysine. The results of these experiments indicate that, as far as rat growth is concerned, the only amino acid deficiency in commercial white bread is lysine.

THE communication on the "Conversion of Cholesterol to Provitamin D 3 in vivo" by Mary Scott, J. Glover and R. A. Morton in Nature of April 2, p. 530, prompts us to publish our results for the provitamin in clams. In order to obtain experimental evidence for the hypothesis that the provitamin D is essentially of endogenous origin, we investigated several years ago the sterols of the viscera and of the eviscerated body of clams. At the time when the clams were collected (late summer) their intestinal tract was filled with a dark green paste, indicating that the food consisted predominantly of chlorophyll-bearing micro-organisms such as algae. The sterols isolated from the viscera contained 21·4 per cent provitamin D (determined spectroscopically and calculated as ergosterol). On the other hand, the sterols from the eviscerated body contained only 7·8 per cent provitamin D. Based on the weight of the fresh material, the viscera contained 0·0418 per cent provitamin D and the eviscerated body 0·0163 per cent. The total provitamin D content of the clams was found to be 0·019 per cent, and 24 per cent of the total provitamin D was in the viscera.

The histidine requirement of the chick was estimated by the National Research Council (N.R.C.) (1954) to be 0.15% of the ration. In a recent publication (Almquist, 1956) the requirement of the growing chick for this amino acid is given as 0.3%. Tests in our laboratory employing completely synthetic diets also indicate that the requirement for histidine is in the neighborhood of 0.3% of the diet. Three experiments were carried out with the synthetic diet shown in Table 1. The amino acid mixture contained all the essential components at the specified levels listed by N.R.C. plus several nonessential amino acids, as shown in. Table 1. Histidine, arginine and lysine were fed as the hydrochlorides. Methionine, isoleucine, phenylalanine, threonine and valine were used in the racemic dl -form, thus doubling the percent in the diet of all of these with the exception of methionine, the dl -form of which is fully active. The growth . . .