MAINTENANCE OF FARM ANIMALS 69 



ing from goitre, brought about probably by a lack of iodine in the feed 

 or a failure to absorb and use the traces of iodine usually present in 

 the feed. Recent investigations 16 have shown that this trouble with 

 the offspring can be overcome by administering iodine in the form of 

 potassium iodide to the pregnant dams. Specific recommendations for 

 the prevention of goitre in pigs, lambs, and calves are given in the 

 respective chapters of Part III. (917, 838, 685) 



IV. ADDITIONAL REQUIREMENTS OF ANIMALS 



We have thus far considered in detail only the requirements of ani- 

 mals for crude protein, carbohydrates, fat, and mineral matter. How- 

 ever, just as vital as the demands for fuel and repair material, which are 

 met by these nutrients, is the need for air, water, and vitamines. It is 

 also necessary that the ration in its physical nature or bulkiness be 

 adapted to the capacity of the digestive organs of the given animal. 



102. Air While animals survive starvation for a considerable time, 



lack of air brings immediate death, as a supply of oxygen is required for 

 all vital processes. Carbon dioxid, which is poisonous if present in too 

 large amounts, is being constantly produced in the body and voided into 

 the air. (88) Therefore, for animals confined to closed stables, as 

 in winter in the northern states, an efficient ventilating system must be 

 provided to keep the air pure. This also will prevent the stable becoming 

 damp and wet, which is likewise injurious to stock. 



It is commonly assumed that a ventilation system should be so designed 

 that the carbon dioxid content of the stable air will not often rise above 

 about 0.167 per ct. by volume. 17 To maintain this degree of purity there 

 must pass into the stable every 24 hours the following amounts of outside 

 air for each head of stock. For well-fed cows, 82,843 cu. ft. ; for horses, 

 55,379 cu. ft. ; for swine, 18,410 cu. ft. ; and for sheep, 7,976 cu. ft. 



Cold outside air entering the stable is warmed by the heat animals give 

 off thru radiation and conduction. (89) On the average the heat thus 

 produced can maintain the temperature of the stable only about 36.5 F. 

 above that of the outside air, even disregarding the heat which is lost by 

 radiation from the stable itself. Therefore in zero weather to keep the 

 stable temperature at 50 F. or above, which is considered desirable for 

 dairy cows, the ventilation should be restricted somewhat below the 

 amounts previously indicated. 



103. Water. Animals can live much longer without solid food than 

 without water. An abundant supply of water is necessary for all the 

 vital processes of the body, such as the digestion and absorption of food 



"Welch, Mont. Bui. 119; Hart and Steenbock, Wis. Bui. 297; Kalkus, Wash. 

 Bui. 153. 



"King, Ventilation for Dwellings, Rural Schools and Stables; Armsby, Jour. 

 Agr. Res., 21, 1921, pp. 343-68. 



