728 Starch Equivalents of Feeding Stuffs, [dec, 



Starch Equivalents. — Another point which has of late years 

 been introduced into the theory and practice of animal nutri- 

 tion, and which has served to simplify the method of making 

 up rations, is also due to Kellner.. It has long been felt that 

 it would be very desirable if all feeding stuffs could have 

 their value for feeding purposes expressed by a single 

 number. Many standards of comparison have been pro- 

 posed, and one of the most satisfactory is starch. It is again 

 to Kellner that we are indebted for the experiments and 

 ideas which have resulted in expressing each food in terms 

 of starch. As the many accurate and painstaking experi- 

 ments which he conducted showed how much fat was pro- 

 duced when given weights of starch were fed to full-grown 

 oxen, and as it was comparatively easy to ascertain the 

 increase in fat when known weights of certain foods or com- 

 ponents of foods were fed, a direct comparison was afforded. 

 It is not necessary to follow in detail the experi- 

 ments which gave the information which led to the 

 establishment of starch equivalents of foods. The general 

 method was to keep full-grown animals upon a maintenance 

 diet, i.e., a diet upon which there was neither loss nor gain, 

 and then find the increase in body fat as a result of feeding 

 with the various foods. Actually in carrying out these 

 experiments the animal was given sufficient food to 

 cause it regularly to gain weight to a small extent; this 

 prevented a decrease which would have been inimical to the 

 success of the work. When starch was added to the main- 

 tenance diet of a full-grown ox it was found that for every 

 ioo lb. of starch which were fed the animal increased in 

 weight to the extent of 25 lb. in round figures. It may 

 therefore be stated that when starch is fed to an animal which 

 is already receiving as much food as it requires for mainten- 

 ance purposes, the increase in fat is one-quarter of that of 

 the starch fed. When sugar was fed instead of starch under 

 the same conditions there was also an increase in body 

 weight, although in this case the gain was not as 

 much as in the case of starch. Protein in a pure state 

 {wheat gluten) and oil behaved similarly in causing an 

 increase of fat in the animal body. The actual figures are 

 -quoted for comparison in Table A on the next page. 



