10 MASS. EXPERIMENT STATION BULLETIN 329 



Table 3. — Hatchability from Pause and Nonpause Birds 

 Nonpause Birds Pause Birds 



Year Number Percent Number Percent 



of Birds Hatchability of Birds Hatchability 



1933 13 83.46 71 78.41 



1934 35 88.69 56 84.05 



Total .... 48 87.27 127 80.90 



Summary 



Certain environmental and hereditary characters were studied, to discover 

 what effect they might have on the presence or absence of winter pause and 

 on the duration of winter pause in production-bred Rhode Island Reds. 



1. Birds hatched during March showed a somewhat higher incidence of 

 winter pause than those hatched during April. Date of hatching gave a nega- 

 tive correlation with pause duration of .2366 + .0242. 



2. Age at first egg showed no correlation with pause duration. 



3. Body weight at first egg was not associated with pause duration. 



4. Short intervals between eggs of a clutch during any winter month had a 

 tendency to shorten the winter pause. 



5. Large winter clutch size tended to shorten the winter pause. 



6. The ability of pullets to lay large numbers of eggs before pausing had a 

 tendency to shorten the winter pause. 



7. In general, a significant reduction in pause duration was associated with 

 long periods of previous egg production. 



8. Short pauses were likely to be followed by greater egg production than 

 were long pauses. Winter pause cannot, therefore, be considered as a re- 

 cuperative period to be followed by increased egg production. 



9. Winter pause very significantly reduced winter egg production. The 

 mean winter egg record for pause birds was 78.95 and for nonpause birds 

 102.94. Winter pause birds averaged to lose about 37 days in the winter 

 productive period. 



10. Mean body weight from housing up to March 1 was essentially the same 

 in pause and nonpause pullets, and showed no relation to pause duration. 



11. Pauses of less than seven days are probably due to different causes 

 than are longer pauses. There is some evidence that pauses of less than 

 seven days are not governed by inherited factors. 



12. Laying-house mortality was not reduced by the winter pause. 



13. Hatchability was not increased by the presence of winter pause. 



