IV] 



FEEDING, EXERCISE AND TRANSPORT 



29 



gastric juices in the stomach, forming chyme 

 (known as chymiflcation). Then it is passed on 

 to the small intestines, where it is mixed with 

 the intestinal juices, forming chyle (known as 

 chylification). Then absorption takes place, 

 and, finally, we arrive at the defaecation of the 

 unabsorbed portions of the food. 



Composition of Food 



106. A healthy and suitable food must possess 

 the following properties : (1) The proper amount 

 and proportion of the various proximate 

 principles ; (2) those adapted to climate, age of 

 animal, and work done by him ; (3) the proxi- 

 mate principles must be contained in a digestible 

 form. For instance, beans and peas contain a 

 higher percentage of protein than meat, but are 

 not so suitable for human use, as they are 

 less digestible, much passing off unused. The 

 nutritive value of a diet depends chiefly 

 upon the amount of carbon and nitrogen that it 

 contains. 



During exercise an enormous amount of 

 carbon is secreted by the lungs in the form of 

 carbon dioxide ; a certain portion of nitrogen is 

 also secreted in the form of urea in the urine. 

 Other impurities are secreted by the perspiratory 

 glands of the skin. It has been found that the 

 carbon secreted in one day is ten times greater 

 than the nitrogen, therefore we must feed the 

 animal in these proportions. Protein contains 

 three and a half times as much carbon as 

 nitrogen, so the extra carbon required will be 

 derived from the fats and carbo-hydrates. As a 

 rule, vegetable food contains an excess of carbo- 

 hydrates (as sugar and starch). 



107. With human food, cooking serves very 

 many important purposes, so with horses cook- 

 ing some of the food has its advantages. Cook- 

 ing vegetable foods destroys parasites and breaks 

 up the starch grains, bursting the cellulose, and 

 allowing the digestive juices to come in contact 

 more readily with the granulose and thus form 

 the sugars. Vegetable foodstuffs contain water, 

 nitrogenous matter, soluble carbo-hydrates, fat, 

 wood fibre and ash. 



The various elements of the different foods 

 are classed as follows : flesh-making, fat heat- 

 making (starch, sugar, and fat), bone-making, 

 wood fibre, and water. 



The chief soluble carbo-hydrates consist of 



ordinary starch (C 6 H 10 5 ), grape sugar (C 6 H ia O a ), 



nd cane sugar (GjjH^On). When saliva is 



ixed with starch, as already stated, sugar is 



1 rmed ; the chemical reaction is : 



Starch + Saliva = Grape sugar 

 = C 6 H 12 6 



H 2 



The following table gives the percentage com- 

 position of the grains, roots, hay and grasses 

 most commonly used : 



108. The digestibility of some of the above 

 foods is approximately as follows : 



Carrots and maize 



Bran 



Barley and beans 



Oats .. 



Wheat straw . . 



Meadow hay . . 



95 per cent. 



93 



84 



75 



50 



43 to 61 



Vhe saliva gives up its water and causes it to 

 ')ine with the starch. 



It is interesting to note that the parotid sali- 

 vary gland of the horse is very large, and prob- 

 ably has become so since he has been domesti- 

 cated and fed on dry oats. 



The suitability of food cannot be conveniently 

 measured chemically, so we must find out its 

 value by observing the effects upon the horse. 

 A wholesome food is not necessarily a suitable 

 one. The state of the faeces is a valuable guide. 

 Fortunately in health the horse's dung is not con- 

 stipated like that of a dog, nor fluid like that of 

 horned cattle ; it is moderately soft, fairly well 

 formed and brittle, light in colour (never dark), 

 moderately damp and free from odour and slime. 

 If loose and unformed it indicates that the food 

 is unsuitable, that it has produced either irrita- 

 tion or a purgative effect. Other foods will 

 cause a slow action of bowels or greater absorp- 

 tion of fluid, and thus cause the faeces to become 

 hard. The longer the waste matter is left in the 



