120 MASS. EXPERIMENT STATION BULLETIN 211. 



Changes in Rate (Intensity) of Production. 



Rate or intensity of production is defined as the number of eggs laid 

 per time unit measured in days. There are several possible time units, 

 such as the month, the initial cycle, the inter-broody periods, the summer 

 period and the spring period. Closely associated with this character is 

 length of clutch, or number of days of continuous (daily) production. 

 Units including Avell-defined rest periods, such as those due to broodiness 

 or the winter pause, are specifically excluded. 



While breeders have been selected, other desiderata permitting, on the 

 basis of high monthly production during the winter, the heterogeneous 

 condition of the flocks in respect to other characters makes comparisons 

 unsatisfactory. The present discussion, therefore, is limited to a com- 

 parison of the highest production in any one calendar month before March 

 1. The use of the calendar month, instead of the highest production for 

 a period of thirty or thirty-one days, although unsuitable in comparing 

 individuals, is sufficiently satisfactory for comparison of flock averages. 

 The average highest monthly production in 1913-14 was 19.28 eggs; in 

 1920-21 it was 21.10, showing an apparent gain of nearly 2 eggs. 



Changes in Seasonal Distribution of Production. 

 It has been pointed out that the season at which increased production 

 comes may be quite as important as an absolute increase. In addition 

 to winter production, the year may be divided into spring, summer and 

 fall, but differing from the calendar seasons. ^ Spring production includes 

 March, April and May, chiefly because the station statistics show that, 

 regardless of changes at other seasons, the average for these three months 

 (Table IV) has remained nearly constant during these experiments. The 

 period, moreover, is characterized by a sharp decline in mean monthly 

 production from March (sometimes April) to June, due almost wholly to 

 broodiness. A slight increase in mean production for this season has been 

 noted with higher annual production. 



1 Other divisions might be made from the biological standpoint, but such divisions vary from 

 flock to flock and with methods of breeding. The divisions used are approximate and somewhat 

 arbitrary. Further, in studying seasonal distribution, the 365-day limit to a year has been dis- 

 regarded. 



