Xo. Olo] 



EGG PRODUCTION 



231 



may be laying at a 75 per cent, rate before going broody, 

 but with the appearance of the first broody period pro- 

 duction falls oft* 40 per cent, of its former rate. In gen- 

 eral it has been found that for each hen the rate for the 

 broody part of the year is only about 60 per cent, of the 

 rate of the nonbroody part. 



It is not known whether the intense development of 

 broodiness in the summer months is directly due to the 

 weather conditions as such or whether it is due to some 

 internal cause or is part of the annual cycle. At any rate 

 it is evident that it operates to decrease the egg produc- 

 tion very considerably. Further discussion will be post- 

 poned until the study of broodiness now in progress is 

 ready for publication. 



Types of Winter Records.— The various factors de- 

 scribed in the foregoing pages combine in many ways and 

 produce as a result different types of records, several of 

 which may now be discussed in more detail. For the 

 present we may divide the various types of records into 

 high (over 30 eggs), mediocre (under 30 eggs) and zero 

 producers. 



High producers (over 30 eggs) may be divided into 

 several subclasses. First, the early maturing, nonbroody 

 high that lays continuously at a high rate and makes a 

 very high record (No. 4846, Fig. 3). Second, the late 

 maturing nonbroody high that lays continuously at a high 

 rate but makes a lower record than the first in direct pro- 

 portion to the difference in maturity. (See Figs. 3 and 

 4.) Third, the broody, early maturing high that lays at 

 a high or fairly high rate' during the laying periods (not 

 shown). Such a bird's' record is cut very materially by 

 the broody periods. Individuals of this type are not very 

 numerous during the winter period. Fourth, there is the 

 high bird that exhibits a pronounced winter cycle or 

 period of good production during the early part of the 

 winter, but which stops after a time and may not lay at 

 all for several weeks. This type is closely related to the 

 bird that lays her eggs in clutches, but because of her 



