FEEDING OF ANIMALS. 327 



Various experiments have been made to determine the loss 

 of nitrogen in sweat. In the sweat of man ammonia and 

 urea have been found. In the sweat of a horse Grandeau 

 and Leclerc l found ammonia, urea, and albumin. Professor 

 F. Smith, of Aldershot, 2 has also examined the sweat of horses. 

 Besides various inorganic salts, he found ammonia, and 3.381 

 per cent of albumin. He reckons that a pint of sweat will 

 thus contain 0.676 ounce of albumin, and that this amount 

 would be equivalent to the nitrogen in 5f ounces of oats. 

 He further thinks it probable that the reduction of sweating 

 by clipping would, with hard work, be equivalent to 1 lb. of 

 corn per day. 



It seems safe to conclude that the loss of combined nitrogen Loss im- 

 by gaseous emanations from the lungs and skin is, for all materkd - 

 practical purposes, quantitatively immaterial The sweat 

 would seem to be a more important source of loss in animals 

 submitted to much muscular exercise. But, even in their 

 case, it does not seem to be large ; whilst in that of the ani- 

 mals of the farm fed for the production of meat or milk, it 

 would presumably be much less material. 



We now come to the consideration of evidence of quite Amounts 

 another kind as to the loss to the manure of the nitrogen of ^j^odS 

 the food, beyond the amount stored up in increase, or removed manure. 

 in milk : namely, that afforded by the results of experiments 

 made to determine the relation of the amount of nitrogen 

 voided in the solid and liquid excretions, to that consumed in 

 the food. Most of these have been made with the animals of 

 the farm ; indeed, most of them have had for their object the 

 direct determination of the amount of the nitrogen of the 

 food consumed which is recovered in the manure in practical 

 feeding. The chief results may be very briefly summarised 

 as follows : — 



Boussingault made experiments 3 with a cow, with a Boussin- 

 horse, and with turtle-doves (probably between 1830 and J^S^" 

 1840). 



In the experiment with a cow, the animal was fed on the 

 same food for about a month, and the results relate to the 

 three concluding days of that period. Boussingault observes 

 that the animal did not suffer any material change in weight. 

 Besides the nitrogen removed in the milk, there was an 

 amount not recovered in the excrements which represented a 

 loss of 13.4 per cent of the total nitrogen of the food. 



In the experiment with a horse, the animal had received 



1 Annates de la Science agronomique, 5 me annie, 1888, tomeii. pp. 311-314. 



2 Journal of Physiology, 1890, vol. xi. p. 497. 



3 Agronomie, Chimie agricole et Physiologie, 2 me ed., 1874, vol. v. p. 144. 



