ENERGY IN FEEDINGSTUFFS AND ITS USES 105 



other than a dry, open shed is not necessary for beef cattle 

 and sheep, except at calving or lambing time. Horses and 

 hogs should have a fairly warm, comfortable enclosure. 



Storage of Energy. — The animal body differs from the 

 machine in that an}^ energy above the amount required for 

 the different forms of work and for heat production is not 

 wasted, but it may be stored in the body, principally as 

 fat, or as protein tissue, and used for the production of work 

 or heat at any subsequent time when the energy of the ration 

 is insufficient, or it may be used for the production of milk. 

 It should be noted, however, that all other demands of the 

 body for energy-, including maintenance, heat production, 

 and voluntary work, must be satisfied before there can be 

 any storage of energy or any energy available for milk pro- 

 duction. 



Energy Values of Feedingstuffs. — From the standpoint 

 of practical stockfeeding, it is the net energy contained in 

 a feed which is of interest. Hence, in speaking of the energy 

 values of feedingstuffs, one usually refers to the net energy 

 values. Armsby's table showing the amounts of net energy 

 contained in the more common feedingstuffs is given in Table 

 31, of the Appendix. 



In general, feedingstuffs may l^e divided into two main 

 groups according to the amounts of net energy contained 

 in them. These two groups are (1) concentrates, and (2) 

 roughages. 



Concentrates may be defined as feedingstuffs which con- 

 tain a relatively large amount of net energy (or digestible 

 nutrients) in a small ])ulk. Ordinarily, concentrates have 

 a net energy value of 60 therms or more per 100 pounds of 

 feed. As might be expected from their definition, they 



