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low vitality and poor hatching quality in eggs, much of the 

 weakness of the brooder chicks, much of the mortality and 

 disease in adult stock can be traced to lowered vitality in 

 ancestors, due in many cases to the immense requirements for 

 production. The average hen is expected to lay in a year 

 from four to five times her body weight in eggs. This means 

 one egg approximately every third day of the year. In order 

 to perform this feat of production she must consume approxi- 

 mately twenty-five to thirty times her body weight in feed. 

 There is, doubtless, no farm animal which is more efficient as a 

 transformer of the raw material into the finished product than 

 the hen. The successful breeding for vigor means the appre- 

 ciation of two sets of factors, — first, the lack of vitality, and 

 second, signs in an individual which determine the presence or 

 absence of vigor. Valuable work has been done by a number 

 of our experiment stations in studying these factors. 



The successful commercial poultryman and the farm poul- 

 try keeper who have studied their birds have learned that 

 forcing, due to heavy feeding, or to intensive conditions, if 

 continued year after year, cannot but, in the end, break down 

 the physical strength of birds so treated. They have also 

 observed that inbreeding for a number of generations, without 

 regard for vigor in succeeding generations, intensifies the char- 

 acteristics of low vitality which the original parents possessed. 

 The use of pullets for breeding purposes, due to their imma- 

 turity, cannot but result in progeny of small size and pos- 

 sessed of less than their full quota of stamina. Forced feeding 

 during the winter and fall, especially of concentrated protein 

 feeds, has the immediate effect of taxing the digestive system, 

 causing the bird to go off its feed and lowering its energy and 

 physical strength. The continued crowding of breeding stock 

 into poorly ventilated quarters, and the giving to them an 

 insufficient amount of exercise, is another direct cause of low 

 vitality. Such conditions will be apparent in the fertility and 

 vitality as possessed by the germ in the hatching egg. Lack 

 of care in hatching and improper range conditions for the 

 growing stock are two other common causes of lack of vigor. 

 Probably the greatest of all causes is the failure of the poul- 

 tryman to select his breeding stock with great care. Breeding 



