TIME INTERVAL FROM FIRST EGG TO STANDARD 

 EGG WEIGHT IN RHODE ISLAND RED PULLETS 



By F. A. Hays, Research Professor of Poultry Husbandry 



INTRODUCTION 



In a preliminary report Hays (1930) has shown that the time required by 

 pullets to attain an egg weight of 57 grams, or about 24 ounces per dozen, varies 

 widely and is influenced by such hereditary traits as age at sexual maturity, 

 weight at sexual maturity, and intensity of laying. The ability to lay 57-gram 

 eggs in a short time after sexual maturity was pointed out as being highly de- 

 sirable economically. 



This report is concerned with the relation between time required to attain 

 standard (24 ounces per dozen) egg weight and various fecundity characters, 

 as well as number of eggs laid in the winter season and during the pullet laying 

 year. A study is also reported on fecundity traits and egg production of the 

 birds that failed to attain standard egg weight the first year. The partial or net 

 correlation has been determined between time required and the following inde- 

 pendent variables: hatching date, age at sexual maturity, weight at sexual ma- 

 turity, winter clutch size, winter pause duration, total days broody, and annual 

 persistency; also the multiple correlation between these seven variables and time 

 required. Greater variability in time required than can be ascribed to the seven 

 variables studied may be assigned largely to hereditary factors that affect the 

 time required to reach standard egg weight. 



Data Available 



Records are available on 409 birds that attained standard egg weight during 

 the pullet laying year and 140 individuals that failed to attain standard egg weight. 

 These birds were hatched from 1928 to 1932, and were all pedigreed Rhode Island 

 Reds bred for high fecundity. The birds included in this study were all geneti- 

 cally early-maturing individuals, that is, beginning to lay at 215 days of age or 

 younger. Each individual was considered as having attained standard egg weight 

 when she had produced five successive eggs averaging 57 grams each. 



EXPERIMENTAL RESULTS 



Population Attaining Standard Egg Weight 



A frequency distribution with respect to time to standard egg weight (the 

 dependent variable) was made on the 409 individuals attaining standard egg 

 weight. The X 2 test showed the lack of a normal distribution. When, however, 

 21 individuals that required less than 16 days to reach standard egg weight and 

 5 individuals that required more than 255 days were omitted, the distribution 



