490 



Feeding Stuffs in August. 



[Aug., 



FEEDING STUFFS IN AUGUST. 

 Professor T. B. Wood, C.B.E., M.A., 



The Animal Nutrition Institute, Cambridge- Univ emit y. 



Since the last issue of these notes in the May number of this 

 Journal, the writer has received a considerable amount of corre- 

 spondence on the subject of the meaning of Food Units and 

 Starch Equivalent, from which it is evident that the vse of these 

 two terms causes much confusion. It has been explained on 

 previous occasions that the value of a feeding stuff is two-fold : 

 it possesses (1) a certain food value and (2) a certain manurial 

 value. The method of calculating the number of food units in a 

 ton of any feeding stuff takes this double value into account,, and 

 the cost per food unit therefore gives a measure of the total 

 value . 



Since, however, the idea of food units includes both manurial 

 and food value, it is not possible to feed according to food units. 

 This has been pointed out in these notes on several occasions, 

 when it has been suggested that feeding should be regulated 

 according to starch equivalents. To buy on the food unit system 

 and to feed according to starch equivalents is certainly confusing. 



The writer has therefore decided to work out prices on the 

 starch equivalent basis in future, so that this confusion may be 

 avoided. This course is possible now that the figures 

 in the tables of manurial values of feeding stuffs, pub- 

 Kshed in Bulletin No. 73 of the University of Leeds 

 and the Yorkshire Council for Agricultural Education.* 

 have been brought up to date. The method of calculation is to 

 deduct the manurial value from the market price so as to get 

 the net cost of the feeding stuff less manurial value, and to divide 

 this net cost by the starch equivalent so as to get the net cost 

 of one unit of starch equivalent. As in the case of food units, 

 one unit is one-hundredth part of a ton, or 2-24 lb. 



Before giving the table in which the calculation is made it is 

 desirable to explain once more what the term "starch equiva- 

 lent " means as used in this connection. This term has been 

 used in several different senses; mostly to denote a theoretical 

 food value determined by calculation. As used in lhese notes 

 " starch equivalent " means the number of 'pounds of starch 

 required to produce as much fat in a store animal as 100 lb. of 

 the feeding stuff in question. 



*These figures were published in this Journal, May, 1920, pp. 190 it 191. 



