Inbreeding in 35 Generations of Development of Cornell S Strain of Leghorns

The average coefficient of inbreeding after 35 years of development of Cornell S strain was estimated at 39% using pedigree data. Based on the number of breeders used and assuming that all breeders were one year old, the expected coefficient of inbreeding would have been 69%. The average age of breeders used in any one year varied between 1.05 and 2.36 years. It is suggested that the smaller coefficient of inbreeding was primarily the result of a decrease in the number of generations possible in the fixed time span of 35 years when the average age of breeders was greater than one year.