Failure of Thioctic Acid to Stimulate Chick Growth1,2

RESEARCH NOTES

739

FAILURE OF THIOCTIC ACID TO STIMULATE CHICK GROWTH1-2 A. B. MORRISON AND L. C. NORRIS

Agricultural Experiment Station and School of Nutrition, Cornell University, Ithaca, New York (Received for publication April 5, 1956)

1 Brief reports of these experiments and of similar experiments conducted at Texas A. and M. College were made at the 11th Distillers Feed Conference, Cincinnati, Ohio, March 7, 1956. 2 The thioctic acid used in this investigation was kindly supplied by Dr. T. H. Jukes of the Lederle Laboratories Division, American Cyanamid Company, and the thioctic acid assays were conducted through the courtesy of Dr. H. P. Broquist, also of this division.

DeBusk and Williams (1955) except that only in experiment 2 was purified casein alcohol-extracted. The thioctic acid content of the casein used in experiment 1 was 0.049 microgram per gram and that of the casein used in experiment 2, 0.036 microgram per gram. The gelatin used in both experiments contained 0.040 microgram of thioctic acid per gram. In accordance with the procedure of DeBusk and Williams (1955), the chicks were placed on experiment after being fed ground corn for the first two days. Each lot contained 18 chicks at the start, and all treatments in both experiments were duplicated. In experiment 1, the chicks were fed the basal ration and the basal ration supplemented with 10, 100, 1,000, and 10,000 micrograms of dl-thioctic acid per kilogram. In experiment 2, the chicks were fed the basal ration, the basal ration plus 2,000 micrograms of dl-thioctic acid per kilogram, the basal ration plus 1% sulfasuxidine and the basal ration plus both these compounds. The results of the experiments are presented in Table 1. The results of experiment 1 showed that under the experimental conditions the inclusion of dl-thioctic acid in the chick diet in quantities up to 10,000 micrograms per kilogram failed to improve the rate of growth of the chicks at 2 or 4 weeks of age. The results of experiment 2 confirmed those of experiment 1 as the rate of gain was not increased by adding thioctic acid to the basal diet either with or without sulfasuxidine. This interpretation of the experimental findings is in accord with a variance analysis of the growth data the results of which showed that none of the

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Stokstad, Broquist and Patterson (1953) reported that they were unable to obtain significant growth increases in chicks by the addition of dl-thioctic acid (lipoic acid) to the diet, either in the absence or the presence of aureomycin or sulfasuxidine. DeBusk and Williams (1955), on the other hand, presented evidence that dlthioctic acid stimulated the growth or food utilization or both of chicks and rats fed purified diets, and chicks fed a cornsoybean meal diet containing alfalfa meal or a commercial chick starter. Except for slower growth, no symptoms of a thioctic acid deficiency were observed in the animals fed the experimental diets. In an attempt to reconcile the discrepancy in the results of these investigators, this laboratory conducted two experiments, one with crossbred New Hampshire X Barred Plymouth Rock chicks of mixed sex, hatched from the eggs of hens fed a corn-soybean meal diet and depleted of unidentified factors, and a second with crossbred Rhode Island Red X Barred Plymouth Rock male chicks obtained from a local hatchery. The results of these experiments are presented in this report. The composition of the basal diet fed the chicks, including that of the salt mixture, was identical with that employed by

740

RESEARCH NOTES

T A B L E 1.—Average gain and feed efficiency of chicks fed thioctic acid Average weight gain

14

Experiment 2 Basal 95 +2,000 meg. dl-thioctic acid per kg. 95 + 1 % sulfasuxidine 98 +2,000 meg. dl-thioctic acid + 1 % sulfasuxidine 98

28

%m. 328(35)*

0.605

308(35)

0.605

338(36)

0.605

315(35)

0.621

310(36)

0.606

338(36)

0.676

345(35) 324(34)

0.667 0.671

338(36)

0.680

* Figures in parentheses indicate number of survivors.

differences in gain in either experiment was statistically significant even at the 10% level. In agreement with the growth data, the ratio of the weight gains to feed consumed was also not improved in either

REFERENCES D e B u s k , B . G., a n d R . J . W i l l i a m s . 1955. Effect of lipoic acid o n t h e growth r a t e of y o u n g chicks a n d r a t s . A r c h . Biochem. B i o p h y s . 5 5 : 587-588. S t o k s t a d , E . L . R., H . P . B r o q u i s t a n d E . L . P a t t e r son. 1953. Role of protogen in a n i m a l n u t r i t i o n . F e d . Proc. 1 2 : 4 3 0 .

INADEQUACY OF CERTAIN SALT MIXTURES USED IN STUDIES OF UNIDENTIFIED GROWTH FACTORS FOR CHICKS G. M. BRIGGS Laboratory of Biochemistry and Nutrition, National Institutes of Health, Public Health U. S. Department of Health, Education, and Welfare, Bethesda, Maryland

Service,

(Received for publication April 7, 1956)

It is known that chicks require several unidentified growth factors, one or more of which may be inorganic. In order to secure unequivocal evidence for the existence of such unidentified growth factors, it is essential that the basal diet used provide all of the known essential nutrients at levels that are high enough to permit the best possible growth. In a number of published reports it appears that less emphasis has been given to the adequacy of known mineral elements than to that of vitamins and amino acids. In our own studies on unidentified fac-

tors, with New Hampshire chicks, we were unable to get growth responses from the addition of the ash of crude feedstuffs to a purified diet (sucrose-soybean protein). The diet contained a salt mixture (Briggs et al., 1952) which supplied the known essential minerals in amounts greater than the minimum levels recommended by the National Research Council (Bird et al., 1954). One explanation for the inactivity of the ash in our experiments might be that chicks from depleted hens had not been used. However, in attempting to find other explanations, we noted that the

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gm. Experiment 1 Basal 112 +10 meg. dl-thioctic acid per kg. 98 +100 meg. dl-thioctic acid per kg. 114 +1,000 meg. dl-thioctic acid per kg. 102 +10,000 meg. dl-thioctic acid per kg. 97

diet

experiment by including thioctic acid in the basal diet. The results of these experiments, therefore, confirm the observations of Stokstad, Broquist and Patterson (1953) and are in disagreement with those of DeBusk and Williams (1955). In view of the fact that the latter research workers obtained growth stimulation in both chicks and rats by adding thioctic acid to the diet, it seems probable that the cause of the discrepancy in the results is not due to a difference in source of the experimental animals, but rather to unexplained differences in environmental conditions.