TYPES AND MARKET CLASSES OF LIVE STOCK 169 



in quantity as to maintain the cows at a uniform body weight. 

 In this way the requirement for maintenance was determined 

 for each cow. A maintenance ration is one that will maintain 

 a resting animal at a uniform body weight; such a ration keeps 

 up the body heat, makes repairs in the tissues, and furnishes 

 energy for the working of the heart, lungs, disgestive and other 

 organs, and for slight movements of the body. If the dairy 

 cow is pregnant, she requires enough feed above maintenance 

 to furnish nourishment for the foetus. Still more feed in excess 

 of maintenance is necessary if she is giving milk as well as carry- 

 ing a calf. Cows vary somewhat in their maintenance require- 

 ments, hence two cows consuming the same amount of feed 

 may have different proportions of their feed available for milk 

 production. For instance, a restless cow has a greater main- 

 tenance requirement than a quiet one; when standing up, more 

 feed is required for maintenance than when lying down. Many 

 other factors affect the requirement for maintenance. It is 

 therefore apparent that an investigation into the cause of differ- 

 ences in the economy of production is not complete unless the 

 requirement for maintenance is determined. This the Missouri 

 Station did by finding how much feed was necessary to maintain 

 each cow at a constant weight while dry and farrow. Other 

 experiments have shown that a well-fed dairy cow uses about 

 43 per cent, of her feed for maintenance, 30 per cent, in the 

 work of converting feed into milk, and about 20 per cent, finally 

 appears as milk. These percentages vary, depending on the 

 nature of the feed and the individual, but a good dairy cow is 

 more efficient as a machine than either the horse or the steam 

 engine. In the Missouri experiment it was found that the 

 higher-producing cow required slightly more feed for mainte- 

 nance; hence, the wide variation in production could not be 

 accounted for by a superiority of the high-producing cow in 

 regard to maintenance. 



During the year of the investigation, Pedro's Ramaposa 

 produced 8,522 pounds of milk and 469.9 pounds of fat. Pedro's 

 Elf produced 3,188 pounds of milk and 169.3 pounds of fat. 

 The former produced 2.67 pounds of milk and 2.77 pounds of 

 fat for each pound produced by the latter. The digestion trial 

 showed practically identical results, the co-efficient of digestion 

 being 64.39 per cent, for the best cow and 64.99 for the poorest 

 cow. Pedro's Ramaposa consumed 1.75 pounds of feed for each 

 pound used by the other cow, and the real cause of the differ 



