6 MASS. EXPERT\[ENT STATION BULLETIN 2,11 



DEFERRED BROODINESS 



The term "deferred broodiness" may be used to indicate the delayed 

 appearance of the broody instinct in the second laying year or later. 

 Goodale, Sanborn and White (1920) recognized the problem of deferred 

 broodiness in Rhode Island Reds but presented no data. Punnett (1923) 

 also referred to deferred broodiness in Leghorn-Langshan hybrids. From 

 the point of view of the breeder who is attempting to eliminate broodiness, 

 tliis delayed appearance of the broody instinct is of considerable im- 

 portance. Naturally the question arises of the accuracy of selecting hens 

 for the non-broody phenotype after one year of laying or more. 



In the total of 210 dams used in the breeding tests, 47 exhibited the 

 broody instinct while they were under observation. In table 2 the amount 

 of deferred broodiness is recorded. 



Table 2. — Time of Onset of BROonv Instinct in Tested Dams. 



Tested Dams 

 Number Percent 



Broody in first year 27 57.45 



Broody in second year 16 34.04 



Broody in third year 4 8.51 



Total number broody 47 



The broody instinct was exhibited by 57.45 percent of the dams during 

 their first laying year. Broodiness wa.i deferred to the second year in 

 34.04 percent of the dams and to the third year in 8.51 percent. The 

 27 dams that became broody in their first laying year are shown in groups 

 1, 2, and 3 of table 1, and 47.59 percent of their daughters were non-broody. 

 Group 7 dams, whose broodiness was deferred to their second laying year, 

 had 78.13 percent non-broody daughters. The group 8 dams, whose 

 broodiness was delayed to the third laying year, had 72.92 percent non- 

 broody daughters. Although the data are limited, there is reasonable 

 evidence that when the broody instinct appears in dams in their first 

 laying year, their daughters are twice as likely to exhibit the trait in their 

 first year as daughters from dams with broodiness deferred to the second 

 or third laying year. (Quantitatively, at least, dams with deferred brood- 

 iness may be superior as breeders to those broody in their first laying year. 



In the group of 210 dams tested, only 22.38 percent exhibited the broody 

 instinct while they were under observation. According to table 2, only 

 57.45 percent of these broody dams were discovered by one year of trap- 

 nest records; but when two laying-year records were available, 91.49 per- 

 cent of the phenotypically broody dams were discovered; and when the 

 records covered three years, probably 98 or 99 percent of such dams would 

 be discovered. From these observations it is clearly evident that the 

 broody trait will persist in a flock until all females are retained to such an 

 age as will bring out all deferred broodiness. At the same time males 

 must be tested through their daughters from aged mothers, and all such 

 daughters must be retained for a long period to discover deferred brood- 

 iness. There is no evidence reported that any flock has as yet been 

 entirely freed of the broody instinct. 



