LABOUR DIET 187 



at once what quantities of other foods will replace 



I lb. of maize. If wheat straw chaff is introduced 

 into the ration to supply the fibrous matter needed 

 for the horse's health, it must be recollected that for 

 each pound of straw 0'116 lb. must be deducted from 

 the total of available food supplied from other sources. 

 In calculating the above ration no mention has been 

 made of the heat requirements of the horse ; these we 

 have seen (p. 182) are equivalent to 7 lbs. of digestible 

 organic matter. As, however, only 31 per cent, of the 

 food available for work actually produces a mechani- 

 cal effect, and the whole of the rest of the ration 

 appears as heat, the requirements for heat are fully 

 met ; and when, as in practice, fibrous foods are em- 

 ployed to a considerable extent, the proportion of the 

 food producing heat is still further increased. 



"Wolff and Lehmann, as already mentioned, reckon 

 a labour ration more simply, but less accurately, in 

 terms of digestible organic matter, excluding fibre. 

 Of such matter they state that a horse of 1,000 lbs. 

 live weight will require 8 lbs. per day for light labour ; 



II lbs. for average labour ; and 13 lbs., or more, for 

 severe labour. 



A diet of meadow or clover hay does not supply 

 sufficient available food for a full day's work, even at 

 a walking pace ; but the young grass of a good pas- 

 ture, and green vetches or lucerne, are sufficiently 

 nutritious for this purpose. Whenever severe labour 

 has to be performed, food of high quality and easy 

 digestibility must be given. 



As already remarked, food containing a large pro- 

 portion of albuminoids is not essential for a labour 

 diet; rations supplying only a small proportion of 



