186 



TECHNICAL BULLETIN 8 



Number of birds 



Mean lengtli of winter pause 



Winter pause standard deviation 



Mean annual production . . . . 



Annual production standard deviation 



Coefficient of correlation .... 



Regression of winter pause on production . 



Regression of production on winter pause 



1348 

 32.39 



±2L77 

 172.51 



±4.1.07 

 —.2107 

 —.112 

 —.398 



.0176 



Tbe mean annual record of the pause birds tiiroughout the period is about 

 17B eggs. Tlie range of variation in annual egg yield is wide, as is shown bj" 

 its standard deviation. Greater honuigeneity in iieritable factors concerned 

 in fecundity should reduce such varialiility. 



The magnitude of the coefficient of correlation is sufficient to indicate that, 

 in general, an mcrease in length of winter pause is accompanied by a de- 

 crease in annual egg production. The time lost in winter pause is not com- 

 pensated for by heavier production either before or after the pause in any 

 class of pause birds. 



m. Correlation Befzveev ^nwni] Production BeloTi' the Mean and the Pres- 

 ence of Winter Pause for the Tolid Population. 



Coefficient of correlation 



+.3056 ± .0132 



Low annual production is significantly correlated with the presence of 

 winter pause as shown in the above table. Even thougli such a short period 

 as a four-d;\y pause is considered, this correlation coefficient is of appreci- 

 able magnitude. Winter pause nuist, therefore, be classed as inimical to 

 highest annual egg yield, for the pause birds averaged but 173 eggs while 

 the non-pause group averaged 189 eggs. 



Generaf, Discrssiox axu Su.mmary. 



The lenglh of the winter laying cycle is unquestionably modified by a 

 series of environmental influences. Some of tliese influences are within 

 while others are beyond control of the poultry breeder. Winter pause is the 

 complement of the winter laying cycle and is important in that it vitally 

 alTects total fecundity. 



Two distinct classes of pullets appear in the flock studied, namely, pause 

 and non-pause. A group of pause birds studied i)eside a group of non- 

 pause birds, both groups hatched on the same date and both groups starting 



