14 BULLETIN 310, U. S. DEPAKTMENT OP AGEICULTUKE. 



BUTTER. 



Many investigators have studied the digestibility of butter under a 

 wide variety of conditions, because of its very extensive use in coun- 

 tries where it is obtainable at relatively low prices. In a number of 

 the earlier determinations the rations used consisted of only one food 

 material in addition to the butter. 



Kubner, 1 as a part of an extended series of experiments, determined 

 the digestibility of a simple ration of butter and potatoes, and of one 

 made up of green beans (540.2 grams) and butter (53.4 grams). 2 The 

 coefficient of digestibility of fat in the first case was 96.3 per cent and 

 in the second 91.5 per cent. In another test, 3 with a ration contain- 

 ing a considerably larger proportion of fat — 240 grams of butter — 

 daily, this fat was 97.3 per cent assimilated. 



Atwater, 4 in studies made previous to his connection with the 

 nutrition investigations of the Department of Agriculture, studied a 

 simple diet of fish (1,584 grams) and butter (30.5 grams), and found 

 that the fat had a coefficient of digestibility of 91 per cent. 



A similar experiment by Malf atti 5 is reported in which polenta (a 

 porridge made of Indian corn meal and butter), supplying 92.5 grams 

 of fat per day, was used. The coefficient of digestibility of the fat of 

 the corn meal alone was found to be 57.86 per cent, while the butter, 

 which supplied by far the greater part of the fat content of the ration, 

 was 97.7 per cent available. 



The variation in digestibility as determined by the different investi- 

 gators is doubtless due to a lack of uniformity of conditions under 

 which the experiments were performed. The results of these early 

 experiments, however, agree fairly well in showing that butter is very 

 completely digested. In later experiments, which are also of interest, 

 a more complex basal ration seems to have been used. 



Mayer 6 studied the thoroughness of the digestion of butter by a 

 39-year-old man and a 9-year-old boy, who were given butter in a sim- 

 ple mixed diet. The average digestibility of butter as determined 

 by three experimental periods, each of three days' duration, was for 

 the man 98 per cent and for the boy 97 per cent. 



Bertarelli 7 investigated the nutritive value of butter, using three 

 healthy men as subjects for one experimental period each. He ob- 

 tained 94 per cent as an average digestibility. 



Huldgren and Landergren 8 used a simple basal ration of rye bread 

 made of rye flour, water, and yeast and baked in hard, thin cakes. 



i Ztschr. Biol., 15 (1879), No. 1, pp. 136-147. 



2 Idem, 16 (1880), No. 1, p. 127. 



3 Idem, 15 (1879), No. 1, pp. 174-176. 

 * Idem, 24 (1887), No. 1, p. 16. 



6 Sitzber. E. Akad. Wiss. [Vienna], Math. Naturw. Kl., 90 (1884), III, No. 5, pp. 328-335. 

 B Landw. Vers. Stat., 29 (1883), pp. 215-232. 



7 Riv. Ig. e. Sanit. Pub., 9 (1898), Nos. 14, pp. 538-545; 15, pp. 570-579. 



8 Skand. Arch. Physiol., 2 (1890), No. 4-5, pp. 373-393. 



