122 maine agricultural experiment station. i909. 



The Relation of the ITen to the Fertility oe Ec.gs. 



There is q rather common behef that when hatching eggs run 

 low in fertiHty the fault is chiefly or entirely in the male bird 

 which is with the flock. For some reason which is difficult to 

 understand very little influence is attributed in the popular 

 mind to the females in causing poor results of this kind, the 

 belief rather being that the male bird has an almost exclusive 

 influence in determining fertility of eggs. It seems somewhat 

 remarkable that this notion of the predominant influence of the 

 male bird in determining the fertility of eggs among poultry 

 should be so widespread, in view of the fact that the popular 

 belief with reference to other domestic animals is exactly the 

 opposite. For example, in cattle and horse breeding the fail- 

 ure of the female to become pregnant (the equivalent in part 

 of the fertilization of the egg in poultr)^) is commonly attrib- 

 uted to some defect in the female rather than in the male. The 

 standpoint which the known facts of biology lead one to take 

 is that in all bisexual animals the influence of the two sexes is 

 in general equal in determining whether any given egg shall or 

 shall not be fertilized. That is to say, there is on general 

 grounds every reason to suppose that the infertility of eggs is 

 as likely to be due to a defect of the female as to a defect of the 

 male and z'ice versa. It seems desirable to determine with some 

 precision whether this general statement is true for poultry or 

 not. When the average fertility for a flock of hens runs low 

 what proportion of this low fertility is to be attributed to the 

 poor breeding performance of the hens and what proportion to 

 the male birds? The practical importance of the question is 

 obvious. If the man who is selling eggs for hatching can learn 

 that one particular hen, for example, in his flock never pro- 

 duces a fertile egg, it will be greatly to the advantage of his 

 trade to eliminate that bird from those which are producing 

 his hatching eggs. 



In order to bring out with completeness and precision the 

 comparative influence of male and female birds on the fertility 

 of eggs Tables VII and VIII have been prepared. These 

 tables show for each breeding pen the following facts : ( i ) 

 The band number of the cockerel which was placed in that pen. 



