FOODS ANIMAL PRODUCTION. 



G79 



"When potatoes arc boiled with the skins removed, there is a very considerable 

 Loss not only of organic nutrients but also of mineral salts. These salts, while not 

 nutrients in the sense in which this term is frequently used, are nevertheless impor- 

 tant in nutrition. They are of especial value, because of the potassium compounds 

 which they contain, and are apparently necessary for health. 



"The greatest actual loss of nutrients seems to be due to the mechanical abrasion 

 of the soft outer portions of the potato while cooking. In this case nearly 3 per 

 cent of the carbohydrates and 4 per cent of the available flesh-forming nitrogenous 

 matter are lost. When the potatoes are boiled with their skins on. the loss of nutri- 

 ents is very slight, consisting chiefly of nonalbuminoid nitrogenous substances and 

 mineral matter. It is self-evident that if it is desired to boil potatoes with as little 

 loss as possible the skins should be left on." 



The digestibility of potatoes and eggs, H. Snyder [U. 8. Dept. 

 Ayr., Office of Experiment Stations Bui. 43,pp. 20-24).— The digestibility 

 of eggs boiled different lengths of time was determined by digesting 

 with pepsin and hydrochloric acid. A test was made with a man 

 weighing 62.5 kg. to determine the digestibility of potatoes when con- 

 sumed with eggs, milk, and cream. The experiment lasted 4.\ days. 

 The food, urine, and feces were analyzed. The feces were separated 

 by means of charcoal taken in gelatin capsules. The daily diet con- 

 sisted of 1,587 gm. of potatoes, 8 hard-boiled eggs, 710 cc. of milk, and 

 237 cc. of cream. It was assumed that 97 per cent of the protein and 

 all of the carbohydrates of the milk, eggs, and cream were digested. 

 The amount of fat in the potatoes was so small that no attempt was 

 made to determine its digestibility. Taking these facts into account, 

 the digestibility of the potatoes was calculated from the digestibility 

 of the total food as actually obtained. The digestibility of the whole 

 diet and of the potatoes is shown in the following table, due correction 

 beinff made for the fuel value of the nitrogen excreted as area in the 



urine: 



Coefficients of digestibility <>/ wholefood and of potatoes. 



The average daily income of nitrogen in the food was 18.14 gm.; the 

 daily excretion was 15.74 gm. in the urine and 2.03 gm. in the feces. 

 Therefore there was a daily gain of 0.37 gm. of nitrogen. This was 

 calculated to be equivalent to 9.88 gm. of protein or 43 gm. of muscle. 



The losses and chemical changes which vegetable feeding 

 stuffs undergo when kept for a long time at a high tempera- 

 ture, H. Weiske (Landic. Vers. Stat., 48 (1897). Xo. 6', pp. 379-389).— A 

 number of samples of medium quality meadow hay were kept in glass 

 jars in a drying oven at 100° for 6 months. Some of the jars were 

 simply covered with filter paper. Twenty-four hours after placing in 



