CORNELL 



IReabitiQ^Course for jfatmers 



Published Monthly by the New York State College op A'^riculture 

 AT Cornell University from November to March, and Entered at 

 Ithaca as Second-Class Matter under Act op Congress July i6, 1894. 

 L.. H. Bailey, Director. Charles H. Tuck, Supervisor. 



SERIES IX 

 BREEDING 



ITHACA, N. Y. 

 MARCH. 1909 



No. 45 

 CONSTITUTIONAL VIGOR IN 

 POULTRY BREEDING 



IMPORTANCE OF CONSTITUTIONAL VIGOR IN THE 

 BREEDING OF POULTRY 



By J. E. Rice and C. A. Rogers 



This bulletin is written primarily for the purpose of pointing out the 

 physical differences that distinguish strong from weak fowls, and to 

 give the results of experiments which show the variation in production 











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Fig. I. — A, Head of Barred Plymouth Rock male showing sexual vigor and mas- 

 culine qualities. B, Head of Barred Plymouth Rock capon (unsexed male) showing 

 characteristic effeminacy. Note sm,all comb and wattles and elongated beak. 



and vigor of offspring between fowls selected with reference to their 

 constitutional vigor. 



Why we must breed for constitutional vigor 



The most important problem before poultrymen is to maintain and 

 increase the constitutional vigor of the flock. This is because we are 

 asking more of the modern hen, in proportion to her live weight, than 



