The effect of a conservation program is mainly determined by the effective population size (Ne) and mating system.Random Mating (RM) and Equimultiple Random Matching Pedigrees Conservation (ERMPC) are programs commonly used to conserve chicken breeds in China.We compared the two mating programs over four pedigree generations by measuring changes in mean inbreeding (Ft) ,the major histocompatability complex (MHC) ,microsatellites,and several phenotypic traits.Egg shell,feather,and shank colors,and egg weight at sexual maturity and at d 482 were consistent across generations for both programs.Generation by mating programs interactions for percent fertility,hatchability,and livability to d 21 were greater for ERMPC than RM,while age at the first egg was greater for RM than ERMPC.Average heterozygosity (He) for the 9 MHC B-G loci was 0.55 and 0.54 for ERMPC and RM,respectively.Polymorphic information content (PIC) for the 9 MHC B-G loci was 0.61 for ERMPC and 0.60 for RM.For the 30 microsatellite sites,He was 0.74 and 0.70 for ERMPC and RM,respectively,with PIC of the 30 microsatellite sites being 0.67 for ERMPC and 0.65 for RM.He of 30 microsatellites was greater for ERMPC than RM.The He and PIC of 30 microsatellites and 9 MHC B-G loci were lower in 3nd generation than other generations.There was no generation by mating program interactions for He and PIC.Although the population sizes were the same,Ne was 300 for ERMPC,and only 200 for RM when there were 60 males and 300 females.Ft was greater in RM than in ERMPC.To maintain maximum possible Ne and genetic diversity in limited groups,ERMPC was the more effective conservation program.