CHANGES IN EGG PRODUCTION. 113 



Reasons for this view have been presented elsewhere. In Table II and 

 Fig. 9 are given the data showing the changes that have taken place. 

 The statements regarding the flocks, as given for winter production, 

 appl}^ here also. 



The integral curves for each year will be found in Fig. 10; frequency 

 polygons are given in Fig. 11, the constants in Table III. 



Changes in Daily Wi^iter Production. 

 The daih' flow of eggs is a matter of some importance to the commercial 

 poultrjonan, because of market fluctuations in price. Daily production 

 curves illustrating this flow show some points not brought out in curves 

 plotted on larger time units. The labor of compiling such curves is great, 

 however, unless birds are penned in such a way that the pen record can 

 be used. A few such pen records have been studied and are shown in 

 Figs. 12 and 13 (see pages 116 and 117). 



J40 200 



310 ISO 



no 160 



250 MO 



220 120 



■|5-'I6 'IS-n '17-18 



YEAR 



Fig. 9. — Mean Annual Production (Solid Line) and Mean Age at First Egg (Dotted 



Line). 



NB, mean annual production, and N' B', mean age at first egg, for low-broody flock. 



No annual record for 1919-20. (See page 108.) 



The points in all curves calling for particular attention are : the marked 

 irregularity in number of eggs laid on consecutive days; the occurrence 

 of waves of several sorts; the angle of slope of the curve at the beginning 

 of production; the sharp descent from the maximum, due to the winter 

 pause, in the curves of early hatched flocks, and the more gradual rise on 

 recovery, with the marked rise in the curve toward the end of February. 

 The later hatched layers do not exhibit such a sharp decline due to the 

 winter pause. The amount is less and recovery quicker. 



