CONSTITUTIONAL VIGOR IN POULTRY* 



C. A. Rogers 

 PART I 

 THE FIRST YEAR'S WORK 



Considerable anxiety is being expressed regarding the large mortality 

 among fowls, and especially among chicks. The recent losses have been 

 sufficiently hea\'y tp dampen the ardor of many previously successful 

 poultry breeders and in not a few instances to financially embarrass or 

 totally discourage others. The lack of a tangible cause to which this 

 large mortality may be attributed intensifies the seriousness of the situ- 

 ation. 



In order to leani whether constitutional vigor is a strong deciding 

 factor in the control of this condition, the experiments herein reported 

 were made. The results are among the first obtained from a series of 

 experiments, observations, and comparisons on constitutional vigor in 

 poultry at this experiment station. 



A Reading-Course lesson (No. 45, March, 1909) on " Importance of 

 Constitutional Vigor in the Breeding of Poultry " has preceded this 

 bulletin. Its conclusions were based, in part, on the same findings. 



OBJECT 



The object of these experiments was to obtain data on the relative 

 power of production and reproduction of pullets which, under the influence 

 of quickly digestible and nourishing foods, were able to overcome an 

 apparent weakness, in comparison with the power of those of their sisters 

 which under the same management had at no time shown weakness. 

 In addition to the practical information obtained on proportionate egg 

 yields, food consumption, and mortaHty, there is special significance 

 in the influence of such parentage on the fertility and hatching power 

 of the eggs and on the constitutional vigor of the chicks hatched. 



SELECTION AND SUMMER CARE OF THE CHICKENS 



Experiment I 



Early in the summer of 1907 a large colony of chicks showed at ten 

 weeks of age such uneven growth and so much difference in health that 

 separation into a strong and a weak flock was advisable. The stronger 



* Mr. W. S. Lyon had the general care of the flocks in the experiments discussed in this bulletin. 



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