^<5?£e JAOQGS l7ja.V 65 



The following table shows the approximate effect of respiration on the 

 composition of air: 



Entering Air Respired Gases 



Oxygen, per cent of volume 20.59 15.74 



Nitrogen and otfier constituents 77.68 75.29 



Carbon Dioxide 0.04 4.00 



Water 1.69 4.97 



100.00 100.00 



It IS the oxygen that is the energy and life-prociucing element; without it 

 there can be no animal life. Oxygen is not to be considered as having any 

 properties as a food, but is rather the necessary element which makes it possible 

 to assimilate and utilize the food. 



While the air is in the lungs, the oxygen which is imparted to the tissues 

 acts upon the carbon of the blood, forming chemical compounds which are 

 thrown off in respiration ; this process resulting in the production of heat and 

 energy so necessary to life. 



A similar process occurs with the burning of coal or wood in the stove. 



The oxygen of the air unites with elements in the fuel to produce that 

 energy we call heat, and the same waste products are formed — carbon dioxide, 

 ammonia gas and water vapor. 



This waste — the smoke and the ashes — must be removed from the stove, 

 and oxygen supplied — or the fire will cease to burn. 



In the same way the respired or breathed air n\ui[ be removed from the 

 stable, and fresh air supplied, so that the cow may have ox\)gen on which to 

 live and supply the energy necessary to produce milk. 



If the stable were air-tight, and no fresh air introduced, the cow would 

 die, just as the fire choked with ashes will soon go out, though it may be 

 plentifully supplied with good coal or \vood. 



Fortunately no stable is air-tight; but in the colder states of the north, 

 most stables are built as tight as possible, to insure warmth for the cows. 



Conditions in this respect are rapidly improving; but even today \ery few 

 stables, comparatnely, pro\ide sufficient ventilation — enough o.vVige;i — to 

 enable the cows to make the most milk i)ossible from the feed and \vater they 

 consume. 



In all such cases, pro\iding plenty of fresh, pure air will result in greater 

 milk yields. 



Actual experiments have proven that cows stabled in ordinary barns with- 

 out adequate ventilation, will give more milk when the proper ventilation is 

 provided; and when the operation of the ventilating system is stopped, their 

 milk vields will immediately decrease to the former amount. 



