264 MASS. EXPERIMENT STATION BULLETIN 258 



unless male C 75450 transmitted high intensity. This male evidently lacked the 

 genes for high intensity for his daughters laid in smaller clutches than their dams. 



Effects of heterosis on broodiness were not apparent in the daughters studied. 

 Male C 75450 apparently did not increase the degree of broodiness as his daugh- 

 ters show no greater proportion of broody individuals than existed in the inbred 

 mothers to which he was mated. 



No genetically persistent daughters appeared in Table 3. Since the inbred 

 mothers used were lacking in persistency, it is evident that the sire of these 

 daughters also lacked the gene P for high persistency. 



In pullet-year egg production these hybrid daughters were inferior to their 

 dams. This may be explained by their late maturity, low intensity and lack of 

 persistency. 



The only recognizable benefit that came from heterosis in these matings was 

 marked increase in body weight. From the standpoint of annual egg production, 

 no benefits were derived. Male C 75450 was evidently lacking in early maturity, 

 high intensity and high persistency. 



1924 Matings 



In order to test further the effects of heterosis, it seemed advisable to continue 

 the matings in 1924. Successful matings were obtained from but two of the 

 hens used in 1923 (Nos. C 1332 and C 3132). These two inbred hens were 

 mated to a cockerel (C 7954) sired by C 75411, an outside "Standard"-bred male 

 from the same source as male C 75450 used in 1923. Cockerel C 7954 was a son 

 of C 6286, a Station hen that was not inbred. 



The observation was made that the progeny of 1923 were slightly heavier than 

 those of 1924 from hens C 1332 and C 3132. It was noted also that there was 

 no mortality of daughters from these two hens in the laying houses for the year 

 1923; while the mortality rate was 33 and 50 per cent, respectively, for 1924. 

 Evidently the direct outcross made in 1923 gave more vigorous offspring than the 

 less pronounced outcross of 1924. 



Early sexual maturity was apparently not affected by inbreeding and came 

 as a dominant from the dams both years. Winter pause occurred in all 1924 

 daughters and was expected from the two dams used. Both dams used in 1924 

 lacked high intensity, but one daughter was high in intensity, showing that the 

 sire must have contributed genes for high intensity. The first dam was non- 

 broody but had one daughter showing broodiness. The second dam carried 

 broodiness and her one daughter was not broody. These facts suggest that the 

 first hen carried one gene for broodiness and that the male used carried the other 

 broody gene. Both the dams for 1924 were low in persistency. The fact that 

 4 out of the 5 daughters were persistent shows that male C 7954 carried P, the 

 gene for high persistency. The annual egg records of the five birds hatched 

 in 1924 were higher than for the birds hatched in 1923, indicating the importance 

 of high intensity and high persistency. 



In general, the results of outcrossing on two successive years indicated that 

 body weight may be increased and vigor somewhat improved in the first genera- 

 tion, but that undesirable traits from the standpoint of fecundity will be intro- 

 duced unless the outcross is made with stock carrying the characteristics neces- 

 sary to heavy egg production. This type of mating was not continued after 

 1924 and the progeny of 1924 were not used for breeding. 



Inbreeding Experiment 



In the spring of 1923 an experiment was begun using Rhode Island Reds to test 

 the effects of different degrees of inbreeding upon the characteristics directly 

 affecting fecundity and upon other characteristics of importance in breeding for 



