60 TECHNICAL BULLETIN 7 



Character of Birds Used. 



Beginning in tlie spring of 1916 the plan of breeding Rhode Ishind Reds 

 for high egg production was somewhat modified. On that year matings were 

 planned to consider early sexual maturity, no winter pause, intensity, i)er- 

 sistency, and especially non-broodiness. Particular attention was given to tiie 

 elimination of the broody tendency by using females non-liroody during the 

 pullet year and males from non-broody mothers for breeding purposes. The 

 original foundation stock was all standard-bred Rhode Island Red. No new 

 blood has been introduced into the flock since the plan of mating for the five 

 characteristics above referred to was inaugurated in 1916. Inbreeding has 

 not been practiced to any considerable extent, but the line of ancestry has 

 been markedly reduced so that the present flock traces to but a small number 

 of the best foundation birds. 



Records Kept 



Records used in the study of broodiness include complete pedigree of all 

 birds used; complete trapnest records of every female as long as retained; 

 date hatched; date of first egg; age at first egg; weight at first egg; nesting 

 records; date of appearance of broodiness; date of placing into broody cooj); 

 date of return to laying house; hatching record of females used as breeders; 

 complete family record of the progeny from each mating; and daily, winter 

 and annual records on all surviving females. 



Intensity. 



Intensity and rate are terms used interchangeably in this report. They 

 refer to the number of eggs laid in a specific interval of time on a percenFage 

 basis of the maximum possible number of eggs in the time considered. 

 December Rate, as used here, is a figure obtained by dividing the number of 

 eggs laid by 31 if the hen began laying on or before December first. For 

 birds that lard their first egg later than December first, tiie rate was calcu- 

 lated by di\iding the number of December eggs by the number of days from 

 first eijij to the end of December. As a short-time measure of intensity this 

 may be considered more accurate than the actual number of eggs laid during 

 December, for obvious reasons. Winter Rate is calculated by dividing the 

 total number of eggs from first egg to March first by the number of days 

 from first egg to March first, less all pauses of four or more days in duration 

 from November first to March first. Annual Rate is calculated by dividing 

 the total eggs from first egg to 364 days thereafter, for all birds that showed 

 no 30-day pause after March first, by the number of days from first to last 

 egg. When a bird stopped laying for thirty or more days after March first, 

 her laying year is assumed to terminate at the beginning of this pause, and 

 her annual rate is calculated by dividing the number of eggs laid by the 

 nvuTiber of laying days before the pause. 



Broodiness. 



Broodiness has already been defined as the tendency of the female fowl to 

 incubate or attempt to incubate eggs. The intensity of liroodiness may l)e 



