INBREEDING IN RELATION TO EGG PRODUCTION 263 



Table 2 shows that the mean weight of eggs that actually hatched from the six 

 different dams ranged from 51.2 grams to 61.3 grams, with a mean of 56.3 grams. 

 The weight of eggs appeared independent of hatchability but was correlated 

 with weight of chicks. Large eggs did not give more vigorous chicks than small 

 eggs as judged by mortality rate up to September first. 



These data do not indicate that the percentage of fertile eggs hatched, termed 

 hatchability, is any indication of the probable mortality rate in chicks up to 

 September first, and these data agree with those of Dunn (1922). 



Male and female chicks did not differ in weight when taken from the incubator. 

 At four weeks of age males began to weigh more than females. The weight 

 difference for the sexes became very pronounced at 150 days when the cockerels 

 weighed practically one pound more than the pullets, or about 23 per cent. At 

 one year of age, males averaged 7.67 pounds and females 6.16 pounds. Mortality 

 rates for pullets in the laying houses were excessive so that the number of complete 

 annual egg records is very small. 



In studying the effects of heterosis upon the characteristics known to affect 

 egg production, it seems advisable to consider only those daughters which lived 

 to finish their first laj'ing year. The data are presented in Table 3. 



Table 3. — Recoed of All Surviving Daughters from the 1923 Matings 



By comparing Table 3 with Table 1, it is possible to discover differences be- 

 tween mothers and daughters which may be assigned largely to the sire used. 

 By this method, something of the effects of heterosis on traits concerned in egg 

 production may be disclosed. 



Age at sexual maturity was affected. Two mothers known to be genetically 

 early maturing unfortunately faUed to produce any of the daughters with com- 

 plete records. Thus all the daughters in Table 3 came from late-maturing 

 mothers. But the actual age at which these daughters began laying generally 

 exceeded that of their dams. The fact seems evident, therefore, that this mating 

 did not reduce the age at sexual maturity in the daughters of these inbred mothers. 



The body weight of these pullets when they laid their first egg showed the 

 pronounced effect of heterosis. Every individual daughter weighed more than 

 her dam at first egg, and the mean weight of all daughters at first egg was about 

 32 per cent greater than that of the dams. 



The effect of heterosis on winter pause was apparently insignificant. Inasmuch 

 as six of the daughters came from pause dams and only two from a non-pause 

 dam, it is probable that heterosis had no effect on winter pause. 



Intensity as measured by winter clutch size ran low in the daughters. Since 

 the two dams C 3544 and C 4014 that evidently carried genes for high intensity 

 had no daughters with complete records, there could be no intense daughters 



