ANIMAL DRAFT POWER 133 
other hand, heavily-worked animals cannot subsist on roughage 
alone because the digestiljle nutrients are so small that they 
cannot consume a sufficient bulk to secure the proper amount of 
nourishment. 
In preparing rations for animals, horses and mules require 
different treatment from oxen because they have smaller stomachs. 
As they have less power to digest foods, they must be fed less 
at one time and at more frequent intervals. 
The degree of digestibility is dependent on two factors ; namely, 
the length of time the food remains in the digestive tract, and on 
the fineness of the division of the food. Mastication is less 
in horses and mules than in oxen because the former must do 
all the chewing before the food is swallowed while ruminants, 
such as the ox, regurgitate their food and chew it at will. 
Students of animal nutrition have prepared tables showing 
the amounts of the various constituents required for animals of a 
standard weight of 1000 pounds, performing a given kind of 
labor. ^ Other weights are in proportion. Such tables are known 
as feeding standards and are an approximate statement of the 
amounts of the different nutrients required by animals and may 
be used as a guide by feeders. 
In general, a horse or a mule requires from 2.3 to 2.5 pounds of 
dry matter containing If pounds of digestible matter for 
each 100 pounds weight. Oxen require about 2.6 pounds of dry 
material, containing the same weight of digestible matter as re- 
quired for horses and mules. 
In calculating rations according to feeding tables, it is only 
essential that the quantities of carbohydrates and fats corre- 
spond approximately, because they both serve practically the 
same purpose and an excess of one may be offset by a deficiency 
of the other. 
The test of the fitness of a ration for a draft animal is the 
ability of the animal to maintain an even weight. Generally, if 
a healthy animal loses weight, it is an indication of insufficient 
food, while an increase denotes an excessive ration. This does 
not refer to minor changes in weight from day to day but to 
changes observed over a period of several weeks. 
Oats are generally preferred to corn for logging horses and 
mules, especially during hot weather, while cracked corn and 
^ The Wolff-Lehmann Feeding Standards are given in the Appendix. 
