HOUSING AND HYGIENE 287 



The portaljle house differs from the permanent house in 

 that instead of being anchored on a foundation it rests on 

 runner sills and may be drawn from one location to another. 

 This is highly advantageous in that it is possible to have the 

 fowls frequenth' on fresh ground; it allows the chickens to 

 be fittefl into a rotation of crops, picking up the waste grain 

 and insects in the field after harvest, and dropping fertility 

 on the field where it can be used. Dryden makes a statement 

 that the droppings of fifty fowls will keep an acre of ground 

 in a high state of fertility, and Purvis^ estimates that one 

 hundred fowls running at large on an acre should in the 

 summer season of six months have added to its fertility the 

 ecjuivalent of at least 200 pounds of sulphate of ammonia, 

 100 pounds high-grade acid phosphate, and GO pounds of 

 kainit. 



In those western States where grasshopper outbreaks 

 occur, a portable house, full of young chickens drawn to the 

 edge of a field in the spring, and moved from time to time, 

 will do very much toward preventing damage in case of an 

 outbreak. If the house is moved at night with the chickens 

 in it, there \\ill be little if any trouble about their returning 

 there to roost. 



For most farms it will pay to have at least one portable 

 house to be used for the rearing of young stock and later for 

 the housing of pullets. Pullets develop much more satis- 

 factorily when range raised, and lay better when they are 

 kept by themselves. When they are turned in with the old 

 stock, they are so abused that their production is cut down 

 very appreciably. 



In the winter time the portable house can be drawn up 

 close to the dwelling. If there are several of them they can 

 be drawn up close together and joined together as shown in 

 Figure 160. A furnace pipe furnishes a covered passageway 

 and the birds can roost in one house and lay and scratch in 

 the rest of them. 



The styles of roofs commonly used in poultry -house con- 

 struction are the shed or single pitch (Figure 161), the gable 



' Poultry Breeding. 



