102 MASS. EXPERIMENT STATION BULLETIN 211. 



320 



300 

 280 



260 



m 



o 240 

 o 



<" 220 

 I 

 > 200 



2 



2 180 



c 



> 



I- 160 



■" 140 



33 

 O 



o 120 



c 



^ 100 



—I 



o 80 

 60 

 40 

 20 



EGGS PEI? MONTH 14 17 20 23 26 1*17 20 23 26 14 17 20 23 26 14 17 20 23 26 



AGE (DAYS) 32 280 240 200 



Fig. 2. — The Effect of Variation in Two Factors. 



14 17 20 23 26 

 160 



Five points of maturity and rate are chosen, and it is assumed that each bird was hatched 

 April 15, was non-broody, was without winter pause and stopped laying Septem- 

 ber 30. 



record. Fig. 2 was made by choosing five points of the first and second 

 characteristics (maturity and rate), assuming that the other three remain 

 unchanged, and showing bj'' artificial records what would be the resulting 

 yearl}^ production. If all the variations of all the characteristics were 

 combined in all possible ways, the number of different egg records secured 

 would be in the thousands.^ Environment is also responsible for much 

 variation in production. 



If the records of the highest producing hens are examined, it is to be 

 noted that they begin early in life (and also fairly early in the season) 

 and continue at a steady and relatively high rate throughout the twelve 

 months. Examined from the negative standpoint, it is noticed that there 

 are no broody pauses, no winter pause, no delay in beginning production, 

 no early cessation of production, no slow rate while laying. A record at 

 the low end of the series is zero, but one only shortly removed shows late 

 maturity, early cessation and slow rate. The problem of the breeder, 

 then, is to devise a method of eliminating the undesirable characteristics 

 from the flock and of securing fairly uniform high production. 



1 It is a point of considerable importance to recognize that the greatest complexity occurs in 

 those records near the mode of the egg production curve, and that those records near each extreme 

 are less complex, so that studies made on a flock composed of either very high or very low pro- 

 ducing birds will be simpler than if made on flocks of average production. 



