FEEDING WORK ANIMALS AND GROWING ANIMALS 455 



Energy for Work. Work is measured in meter-kilograms, or 

 foot-pounds. A meter-kilogram is one kilogram raised to the 

 height of one meter. Exact experiments have shown that one 

 large calorie, if completely transformed into kinetic energy, can 

 perform 425 meter-kilograms work. Experiments have shown 

 that an animal can utilize for work about one-third of 

 the available energy in the food. In ten experiments on 

 a man climbing stairs, the percentage was 33.1 per cent., 

 and in eighteen experiments on a horse, it was 29 to 

 38 per cent. It is estimated by Kellner that, after allowing for 

 all losses, I gram of pure protein digested will yield 656 meter- 

 kilograms work, i gram of fat 1,214, and I gram of carbohydrate, 

 533. The rate of work, and the kind, both affect the consump- 

 tion of nutrients, also the shape of the animal as related to the 

 kind of work done. Being accustomed to a particular kind of 

 work also decreases the oxidation of nutrients. It is said that a 

 man working a treadmill oxidized 25 per cent, less nutrients after 

 56 days work, though doing the same quantity of work per day. 

 According to the structure of the working animal, the develop- 

 ment of its muscles, and the position of the extremeties doing 

 the work, the portion of the energy which appears in the work 

 varies. For moving their own bodies, Zuntz found a variation 

 of 0.284 to 0.441 calories per i kilogram weight and I meter dis- 

 tance with different animals. Fatigue increases consumption of 

 energy. 



Rations for Working Animals. Animals when at work require 

 little more proteids than when not at work; a nutritive ratio of 

 i : 7 is sufficient. 



Horses will work off nutrients fed in excess of the maintenance 

 ration by increased movements in the stall, so that it is not 

 possible to assume that the maintenance ration is secured when 

 an equilibrium between income and outgo is secured. 



Standards for Work Animals. Two methods are used for 

 studying the needs of working animals. One is to determine the 

 maximum amount of work which can be secured with a given 

 ration without loss of condition. The other method consists in 



