MASSACHUSETTS ANIMAL INDUSTRY ^59 



Percentage Energy Efficiency of Feeds for Horses. 



The total energy contained in all feeds tested, expressed in therms, was 

 205.46 with extremes of 191 and 229, the latter figure being obtained from 

 brewers' grains which contained considerable fat. The therms of total energy 

 per 100 pounds of dry matter, for most cattle feeds, will not vary nmch from 

 200, except for those having more than tiie ordinary amount of fat. 



The percentage of energy utilized — net energy — varied widely, from zero 

 in case of corn cobs and oat hulls to 57 in case of corn. Two samples of 

 alfalfa showed extremes of from 7 to 18 per cent of energy utilized, with an 

 average of 13; six samples of Timothy hay from 9 to 19, with an average of 

 14. The amount of net energy and the percentage of energy utilized in coarse 

 feeds depends evidently upon stage of growth. Corn was 57 per cent utilized, 

 oats 57 per cent, cottonseed meal 36 per cent, and wheat bran 26 per cent. 



We fail to find on record data of the utilization of energy of individual 

 feeds by horses. It can be said, however, in general, that the less the per- 

 centage of crude fiber, and in roughages the less mature the material, the 

 greater will be the energy available. Armsby bas computed the availability 

 of the energy for ruminants as varying between 5 and 24 per cent for rough- 

 ages, 46 per cent for corn and hominy meals, and 29 per cent for wheat bran. 



Summary 



The results of the feeding trials with horses, reported in the preceding 

 pages, may be summarized as follows: 



Timothy hay and alfalfa had about the same net energy value, but different 

 samples varied widely, depending upon the stage of growth. 



Corn cobs and oat hulls were without net energy value. 



The cereal grains had substantially the same net energy values — somewhat 

 more than did the high-grade nitrogenous concentrates such as cottonseed 

 and linseed meals. 



Wheat bran had a low energy value and as a source of nutrition proved 

 inferior to other concentrates fed. 



The protein in dried brewers' grains was well utilized, but the results for 

 net energy v/ere uncertain. This material is recommended more as a feed 

 for dairy stock than for horses. 



Cottonseed and linseed meals have quite high net energy values and their 

 protein is well utilized. They may serve in limited amounts (1 to 2 poimds 

 daily) as a supplement to the grain ration for hard-worked horses. 



The percentage energy utilization varied from 57 per cent in case of corn 

 to zero in case of corn cobs and oat hulls; the energy in timothy hay and 

 alfalfa hay was utilized to the extent of from 7 to 19 per cent with an average 

 of 14 per cent. 



The net energy value of feeds depends to a considerable extent upon the 

 percentage of crude fiber present — the higher the percentage of fiber, the less 

 the net energy and vice versa. In case of coarse feeds, the later the stage of 

 growth and hence the more mature the material, the less its net energy value. 



The character of fiber influences its digestibility and net energy value. 

 Fiber in straw and oat hulls is less digestible than in corn bran and in early 

 cut hay. The more mature a plant, the more woody the tissue becomes, with 

 an increasingly lessened digestibility. 



