51 



pullets gain at a different rate shortly before laying than two months or more 

 before they lay their first egg. The records of the 413 pullets that began to lay 

 at 206 days or less have been tabulated to show the degree of correlation be- 

 tween gain in weight and winter fecundity. Constants derived are as follows: 



Number of birds 413 



Mean daily gain .029'-2 



Daily gain standard deviation ±.0090 



Mean winter production 54.94 



Winter production standard deviation .... ±21.09 



Coefficient of correlation +.2055 ±.03 18 



The mean rate of gain on this group of pullets beginning to lay at from 150 

 to 206 days old is slightly greater than that for the entire flock. This seems 

 to indicate that there is a tendency for the rate of gain to increase shortly be- 

 fore laying. But the coefficient of correlation is .2055±.0318 as compared 

 with a coefficient of .2899 ±.0220 for the entire flock. Such a difference must 

 be interpreted as evidence that the rate of gain shortly before the first egg is a 

 less reliable indicator of future winter fecundity than is the rate of gain over a 

 longer period before the first egg. 



Weight at 150 Days versus Age at First Egg. 



In order to discover if the weight of a pullet at a particular age previous to 

 the time she lays her first egg is an index to the probable age at which she will 

 begin laying, the 150-day weights on 846 pullets have been tabulated with 

 their respective ages at first egg. Constants obtained are as follows: 



Number of birds ........ 846 



4.02 



deviation ±.54 



210.35 



±27.74 



-.2135±.0221 



i\umoer oi oirus 



Mean weight at 150 days 



Weight at 150 days standard 



Mean age at first egg 



Age at first egg standard deviation 



Coefficient of correlation 



A negative coefficient amounting to .2135±.0221 was obtained. Such a 

 constant indicates that heavy weight at 150 days is associated with early 

 production in about one case out of five. In other words, if all other con- 

 ditions were kept constant, selection on the basis of heavy weight at 150 days 

 would be advantageous for winter production. 



Weight at First Egg versus Age at First Egg. 



Does body weight at first egg vary directly with age at first egg or are there 

 other influences operating so that the element of time is not alone responsible 

 for the weight? If the element of time were alone responsible for weight varia- 

 tion in any particular breed, selection for early sexual maturity would reduce 

 body weight because sexual maturity tends to check skeletal development so 

 that later weight accumulation is largely of adipose tissue. The degree of cor- 

 relation between weight at first egg and age at first egg has been calculated on 

 821 pullets to discover how important a relationship does exist between weight 

 and age. The constants obtained follow: 



Number of birds .... 



Mean weight at first egg . 



Weight at first egg standard deviation 



Mean age at first egg 



Age at first egg standard deviation 



Coefficient of correlation . 



The coefficient of correlation here shows that about half of the large pullets 

 owe their weight to the time element. The other half are large because they 

 possess a different capacity for growth than the first. By developing those 



