MAINTENANCE AND WORKING REQUIREMENTS 45 



modern methods and great scientific detail, gives the 

 amount required as 6*4 lbs. of digestible nutrients when 

 the total ration contains not more than 3 lbs. of crude 

 fibre, and this limiting of the amount of fibre is one 

 reason why a mixed diet of corn and hay is more 

 economical than one of hay alone. Kellner investigated 

 this question with care in two ways, and his conclusions 

 are of considerable practical value, because they are easy 

 of application. In his first experiment he fed a number 

 of bus-horses on one-third their working diet, and, after 

 periods varying from forty to forty-eight days, he found 

 they had lost weight to an average extent of 5 per cent., 

 so proving that the ration was inadequate. He then 

 changed the ration to half the ivorking scale^ and after 

 from twenty-five to thirty-three days the horses had 

 recovered their former weight, and even exceeded it by 

 an average of 1*5 per cent. Evidently the new ration 

 was too good for maintenance. He then took a fresh lot 

 of working horses, and gave them five-twelfths of their 

 working diet whilst keeping them at rest, and this he 

 found to be quite sufficient — in fact, after thirty to forty- 

 eight days they had increased on the average something 

 over 1 per cent, of their weight. Thus Kellner concludes 

 that five-twelfths of a suitable working ration is sufficient 

 for purposes of maintenance. In two other series of 

 experiments Kellner determined the maintenance ration 

 in terms of digestible starch, the quantity required being 

 3'3 kilos, for horses weighing 500 kilos., or, in other 

 words, nearly 7 lbs. per 1,000 lbs. weight. 



Thus we may conclude that for maintenance alone a 

 horse of 1,000 lbs. weight requires an amount of food 

 providing the equivalent of 6J to 7 lbs. of digestible 

 starch. This must necessarily contain enough protein 



