6 MASS. EXPERIMENT STATION BULLETIN 364 



The last graph in Chart 1, showing body weight at first egg, has something of 

 a bimodal aspect and indicates that weights taken at this stage of life are not 

 likely to furnish a true criterion of what adult weight may be. 



The mean monthly body weight of all birds in all experiments is recorded 

 in Table 1. 



Table 1. — Mean Monthly Body Weight 

 (Three years combined. Includes all birds weighed.) 



Month 



September 



October 



November 



December 



January 



February 



March 



April 



May 



June 



July 



August 



September 



The mean weight records indicate that the greatest monthly increase occurred 

 during the first month in the laying houses. Only the first two units of about 

 256 birds each were housed early in September each year, and the third unit of 

 about 250 birds was housed near October 1. On this basis the data showed a 

 mean increase of .68 pound which figure is lower than the actual increase in 

 houses 1 and 2. These data indicate that pullets, if housed when about 10 percent 

 of the birds are actually laying and the others just ready to begin laying, will 

 show a very great increase in weight during the first month. The data show that 

 from October 1 to February 1 there was a monthly increase of nearly .25 pound 

 for each individual. 



Maximum body weight of the first laying year was attained about March 1, 

 when the birds ranged between 11 and 12 months of age, after which there was a 

 monthly decline to about September 1 when weight increases were again noted. 

 The data showed a mean weight at housing of 5.20 pounds, a maximum weight 

 of 6.63 pounds, and a final weight of 6.32 pounds. If these are representative of 

 the normal, a weight increase from housing to the maximum would be about 1.5 

 pounds and a weight loss between the maximum and the final weights would be 

 about one-third pound. The difTerence between the initial and final weights would 

 be slightly over one pound. 



Relation between Body Weiglit and Egg Weiglit 



2. Monthly Body Weight and Monthly Egg Weight 



Daily egg weights were taken for a full year on one unit of 250 birds in each 

 of the three years. For studying the relation between body weight and egg weight, 

 only those birds that were bred for egg production and survived the year were 

 included. The gross data are presented in Table 2. 



