BODY WEIGHT AND EGG PRODUCTION 15 



weight was regular but less rapid. In December, January, and February, winter 

 pause appeared and greatly reduced egg production. Mature body weight was 

 attained in March (6.57 pounds) and was accompanied by majvimum egg pro- 

 duction. From April to August, body weight fell to 6.21 pounds, representing a 

 loss of about .4 pound. During this same period egg production declined at a 

 slightly greater rate than body weight. In the month of September, body weight 

 increased slightly to 6.24 pounds, but egg production fell to about the same level 

 as appeared in the first laying months. These data in general showed consid- 

 erable parallelism between body weight and monthly egg production during the 

 first laying year. Since the mean hatching date was about March 25, the mean 

 age on March 15 was about 355 days when mature body weight was attained. 



Summary 



Body weight records were obtained on 2,283 Rhode Island Red pullets to study 

 the significance of body weight in breeding for egg production. The data obtained 

 seem to warrant the following deductions: 



1. Laying pullets increased in weight at the highest rate during the first month 

 of laying. After the first month there was a monthly increase of about one-fourth 

 pound up to the mature weight attained at eleven to twelve months. During 

 summer there was a decrease in body weight up to September, averaging about 

 one-third pound for each individual. 



2. There was considerable parallelism between mean monthly body weight 

 and mean monthly egg weight. Maximum egg weight occurred about one month 

 earlier than maximum body weight. 



3. Satisfactory winter egg weight did not occur unless pullets averaged to 

 gain one pound or more in weight from housing to the end of the laying 3'ear. 

 Increases greater than one pound were accompanied by larger winter eggs. 



4. There was a significant positive correlation between maximum body weight 

 and annual egg weight. 



5. A statistically significant, though not intimate, correlation was observed 

 between weight at housing and persistency. 



6. Maximum body weight gave a statistically significant negative correlation 

 with persistency, but the constant was of small magnitude. 



7. There was a consistent decline in mortality in the laying houses as the 

 weight of pullets at housing increased. 



8. Groups of pullets having an increase in weight of 1.5 pounds between 

 housing and March 1 had the lowest subsequent mortality. Removal of light- 

 weight pullets on March 1, therefore, offers an effective means of reducing 

 subsequent mortality. 



9. Mature body weight showed a statistically significant negative correlation 

 with annual egg production. The absolute magnitude was so small, however, 

 as to indicate only a remote association. 



10. Pullets increasing one pound in weight during the first laying year gave 

 the most satisfactory egg records. Birds losing weight or with unchanged weight 

 gave unsatisfactory egg records. 



11. Considerable parallelism was observed between monthly body weight 

 and monthly egg production. The highest level of egg production occurred when 

 body weight was at its maximum in March and April. 



12. In general, body weight offers a valuable guide to the breeder, particularly 

 from the standpoint of egg size and laying-house mortality. 



