FERTILITY IN RHODE ISLAND REDS 13 



Table 9. — Fertility of Inbreds, Outbreds, and Checks 



Inbreeding 

 1922-1932 



Brother x Sister 32 



Half-brother x Sister 60 



Sire X Daughter 13 



Son X Mother 11 



1933-1936 



Brother x Sister 3 



Half-brother x Sister 9 



Sire X Daughter 2 



Son X Mother — 



Combining all years 



Brother x Sister 35 



Half-brother x Sister 69 



Sire X Daughter 15 



Son X Mother 11 



Checks 305 



Outside Males 



Outbreeding 



W 2 



D 14 



S 4 



T-1922-1932 10 



1933-1936 7 



Total 17 



P 6 



73.57 



9.63 



77.26 



5.56 



In the inbred group mean fertility was slightly higher from full brother-sister 

 matings. Son-mother matings gave a slightly lower mean value than half- 

 brother-sister matings. Matings of sires to their daughters gave a very low 

 fertility record. On the basis of percentage of unsuccessful matings, son-mother 

 was the most favorable with all matings successful, while sires mated to daughters 

 gave 14 percent of unsuccessful matings. On the basis of mean fertility as well 

 as of unsuccessful matings, all types of inbred matings except sire on daughter 

 were superior to the check group. 



In general, outbreeding raised the mean fertility level above that of inbreds 

 or checks. The D males, the T .stock used in the last four years, and the P stock 

 crosses did not raise the mean fertility significantly above that of the checks. 

 On the basis of percentage of unsuccessful matings, all outside stock proved 

 superior to the checks but not superior to three of the four types of inbred matings. 



