IReprinted from SCIENCE, N. S., Vol. LIV., No. 1393, Pages 824-226, Sept. 9, 192 f] 



THE SECOND- YEAR RECORD OF BIRDS WHICH DID AND DID NOT LAY 

 DURING INDIVIDUAL MONTHS OF THE PULLET YEAR 



The egg output of the commercial poultry 

 plant is due in part to birds in their first 

 and in part to birds in their second year. 

 At some time during the first year the number 

 of pullets is reduced to the number which is 

 to be retained as hens during the second 

 year. 



It would be of obvious advantage if the 

 birds sold from the flock as pullets could be 

 those which if retained would make the poorest 

 record in their second year. If the birds 

 destined to be the highest producers in the 

 second year could be selected on the basis of 

 some criterion recognizable in the first year, 

 it should be possible to raise the average pro 

 duction of the flock as a whole by increasing 

 the average production of the hens. 



In the course of a general investigation of 

 the problem of the prediction of the egg pro 

 duction of the domestic fowl from the records 

 of short periods, we have availed ourselves 

 of the opportunity of considering the relation 

 ship between first and second year laying 

 activity presented by the data of the Vine- 

 land International Egg Laying and Breed 

 ing Contest. As one phase of this work 1 wo 

 have sought to determine to what extent the 

 simple criterion of laying versus not laying 

 in any month of the first year may be used 

 in predicting the record of the second year. 

 The criterion has already been considered 

 in relation to the prediction of first year egg 

 record. 2 While our immediate purpose is the 

 consideration of the second year production 

 of birds which did and of those which did not 

 lay during given months of the first year, 

 it seems desirable to give the mean first 

 year productions of these birds as well. For 

 comparison the results deduced from the data 

 of the International Egg Laying Contest at 



1 Other phases of the investigations will be re 

 ported in detail elsewhere. 



2 Harris, Blakeslee and Kirkpatrick, Genetics, 

 3. 42-44, 49-56, 1918. 



Storrs during the year 1913- 14 and 1914- 

 15 3 are laid beside those presented here from 

 the Vineland data. 



The essential constants appear in the ac 

 companying table. This gives the per cent, 

 of the flock which did and which did not lay 

 during the months of the first year in which 

 any considerable proportion of the birds did 

 not lay. The average annual production for 

 these birds in the first year of both the Storrs 

 (1913- 14 and 1914- 15) and the Vineland 

 (1916- 17) contests and in the second year 

 (1917- 18) of the Vineland contest are shown. 

 While the actual differences in egg preduction 

 are the data of practical significance, com 

 parison between the three series is facilitated 

 by expressing the differences between these 

 annual means for the birds of the two classes 

 as percentages of the actual annual average 

 productions 4 of the flock. 



Considering first the records of the pullet 

 year we note that for the Storrs series the 

 birds which laid in any given month show an 

 average annual (pullet year) egg production 

 of from 27.4 to 82.8 eggs higher than those 

 which did not lay or from 17.9 to 54.1 pe- 

 cent. For the Vineland series the difference 

 in the production of the two groups ranges 

 from 36.7 to 65.5 eggs or fr^ni 21.1 to 37.6 

 per cent. Thus the difference in the annual 

 egg production of the birds which did and 

 which did not lay in any given month, as 

 well as the percentage of the birds which 

 are not laying, varies greatly according to 

 the month considered. During the months 

 of November, December and January the 

 percentage differences in the annual produc 

 tion of the two groups of birds is higher in 

 the Vineland than in the Storrs series 



s Harris, Blakeslee and Kirkpatrick, loc. cit., 

 p. 42. 



4 These are 153.19 eggs for the first year at 

 Storrs, 174.05 eggs for the first year at Vineland, 

 and 139.79 eggs for the second year at Vineland. 



