WINTER PAUSE IN RHODE ISLAND REDS 5 



The mean pause duration in the birds having winter pause fluctuated widely 

 in the different time-interval classes. No consistent relation was observed, 

 however, between time interval and pause duration in the five-month period. 

 There is some evidence to indicate that rapid layers will pause for a shorter 

 period than slow layers. 



5. Winter Clutch Size and Pause Duration 



The average winter clutch size between first pullet egg and March 1 has 

 been used extensively as a measure of intensity. Clutch size has recently been 

 shown by Hays (1936) to be intimately associated with the time interval be- 

 tween eggs within the clutch. It is desirable to know whether the rate of laying 

 measured by clutch size affects the duration of winter pause. The coefficient 

 of correlation was calculated and the regression was found not to be strictly 

 linear. The constants are as follows: 



Number of birds 

 Mean winter clutch, eggs 

 Clutch standard deviation, eggs 

 Mean pause duration, days . 

 Pause standard deviation, days 

 Coefficient of correlation 

 Correlation ratio 



693 



3.21 



±1.31 



37.11 



±24.31 



1803 ± .0248 



.2349 



The population may be considered as made up of intense layers because a 

 mean clutch size of 3.21 indicates that both genes for high intensity must have 

 been present in the majority of birds. The magnitude of the standard devia- 

 tion suggests, however, that clutch size fluctuates widely in the flock. Since 

 the regression of pause duration and clutch size is not strictly linear, the cor- 

 relation ratio must be used instead of the coefficient of correlation. This 

 constant indicates a negative association amounting to . 2349 and gives evidence 

 that rapid layers are likely to pause for a shorter period than mediocre or slow 

 layers. 



6. Production Previous to Pause and Pause Duration 



The assumption is sometimes made that winter pause may be a rest period 

 following a considerable interval of heavy laying. If this were the case, greater 

 length of pause should occur in the birds with highest previous egg records. In 

 the previous section it has been shown that intense winter layers are likely to 

 pause for shorter periods than mediocre layers, which indicates that rapid 

 functioning of the reproductive organs does not deplete the pullet sufficiently 

 to necessitate a long recuperative period. In order to discover the relation of 

 previous egg production to pause duration, the coefficient of correlation was 

 determined as the regression was linear. 



Number of birds .... 

 Mean previous production, eggs . 

 Production standard deviation, eggs 

 Mean pause duration, days . 

 Pause standard deviation, days . 

 Coefficient of correlation 



693 



54.06 



±29.80 



37.11 



±24.31 



.2224 ±.0244 



