DIGESTIBILITY OF SOME ANIMAL FATS. 



9 



It seemed of interest also to study the digestibility of the fat from 

 different parts of the same animal, since these are known to vary 

 materially in composition, hardness, culinary qualities, etc. In a 

 series of feeding experiments to determine the best ration to use for 

 producing firm rather than soft pork, Shutt ^ found that the com- 

 position and physical properties of fat from animals receiving dif- 

 ferent rations varied considerably. In some cases the melting 

 point of soft bacon was practically 10° C. lower than that of firm 

 bacon, and the fat of very young pork was almost always softer than 

 that of mature animals. Henriques and Hansen ^ investigated the 

 properties of the outer layer of fat in an animal as compared with 

 that in the interior of the same animal body, reporting that the 

 inner and outer layers of fat are characterized by different iodin 

 numbers and soHdification points. In similar studies reported by 

 Richardson,^ the melting points of samples of leaf lard from oily hogs 

 averaged several degrees higher than the back fat. Richardson and 

 Farey * later found that the melting points of samples of back fat, 

 leaf lard, and ham fat varied as much as 12° to 22° C. 



While the fat of beef animals may not exhibit as wide a variation 

 in physical characteristics as occurs in other animals, it is well known 

 that brisket fat is quite different from kidney fat. It is softer and 

 has a somewhat granular appearance and has some special culinary 

 uses. Inasmuch as this variation in characteristics exists, it has 

 seemed desirable to test whether there may be a corresponding dif- 

 ference in availability to the body. Accordingly, experiments were 

 undertaken in which the digestibility of brisket fat was studied under 

 conditions identical with those maintained .in the study of beef 

 kidney fat. 



The material used for this purpose was purchased in the open 

 market, separated from the connective tissues of the brisket by the 

 method of rendering previously described, and incorporated in the 

 blancmange which formed a part of the simple mixed diet used in 

 the digestion experiments. The results of these experiments are 

 tabulated on the following page. 



1 Canada Expt. Farms Rpts. 1899, pp. 151-155; Canada Expt. Faxms Bui., 38 (1901). 

 '2 Skand. Arch. Physiol., 11 (1901), No. 3-4, pp. 151-165. 

 3 Jour. Amer. Chem. Soc, 26 (1904), No. 4, pp. 372-374. 

 ' « Idem, 30 (1908), No. 7, pp. 1191, 1192. 



70239°— Bull. 507—17 2 



