APPLICATION OF PRINCIPLES OF BREEDING 489 



two small matings (the second of which is made up of females 

 judged less desirable as mates for him but likely to produce some 

 good birds) or mate him with females of several slightly different 

 types and keep the eggs separate by trap-nesting the hens. When 

 it is inconvenient to keep hens in as small flocks as ten or fifteen, 

 many poultry keepers keep from twenty-five to thirty-five hens in a 

 flock and use two males, alternating them at regular intervals. 



When hens in large flocks are used to produce eggs for hatch- 

 ing, the proportion of males used is much smaller than for separate 

 matings. With medium-sized fowls six males to one hundred 

 females is generally considered sufficient. Good results have been 

 reported from flocks of Asiatics with the same proportion of 

 males. With large flocks of Leghorns the same proportion is used 

 by many breeders, but others use a smaller proportion of males, 

 some as low as three to one hundred hens. 1 



In ducks the usual mating ratio is one male to five females until 

 warm weather (May or June) ; after that, one male to eight or ten 

 females. As the males are not quarrelsome, and interfere with each 

 other very little, breeding flocks may be of any desired number. 

 Average flocks contain from thirty to forty breeders. In turkeys one 

 male is mated with any number of females up to fifteen or twenty, 

 the usual number being ten or twelve. All other kinds of poultry 

 either pair or mate in small families. 



Period of fertility. Fertile eggs are often obtained, on the sec- 

 ond day after the introduction of a male, from hens previously 

 kept in celibacy, but usually fertility from a new mating is low for 

 a week or two, especially in cold weather. Experiments have shown 

 that hens may continue to lay fertile eggs for nearly three weeks 

 after separation from the male, and that the fertility is likely to be 

 as good for a week or ten days after the removal of a male as it 

 was while he was present. In turkeys the influence of an impreg- 

 nation is said to continue for a very much longer period, but this 

 view seems to rest on a small number of instances not very well 

 authenticated. Accurate observation is difficult, and the roving 



1 1 cannot say positively that fertility runs better in the large flocks with the 

 wider mating ratio, but reports from breeders indicate to me that it does. The fact 

 of the very regular difference in mating ratio for separate matings and miscella- . 

 neous matings indicates more efficient service of the males under such conditions. 



