Magnitude of inbreeding depression could be different among descendants of various founder animals, when recessive genetic composition of a population is unevenly distributed among founder animal genomes. Reproductive records of Baluchi sheep for the litter variables size at birth (LSB), size at weaning (LSW), mean weight/lamb born (LMWLB), mean weight/lamb weaned (LMWLW), total weight at birth/ewe lambing (TLWB) and total weight at weaning/ewe lambing (TLWW) were used to examine heterogeneity in inbreeding depression between founder animals. Pedigree-based inbreeding coefficients were proportioned into components coming from founder animals and Mendellian contribution from non-founder animals. Two approaches were used to assess effects of inbreeding: overall inbreeding coefficients or partial inbreeding of the four main founder animals as possible covariates included in statistical models. Among the traits evaluated, there were effects on LMWLB, LMWLW and TLWW of inbreeding with there being a −8, -48, and −95 g decrease per 1% increase in inbreeding, respectively. Linear regressions of traits on partial inbreeding coefficients due to founder animals were of different magnitudes and ranged between -0.12 and +0.128. Heterogeneous contribution of founder animals to inbreeding depression occurred for LSB, LMWLB, and TLWW. These results indicate there was uneven distribution of recessive genetic composition among genomes of founder animals or differences in selection pressures on unfavorable alleles between different founder lines. The observed variation in founder-specific inbreeding depression indicates a small number of alleles with major effects are contributing to inbreeding depression.

当种群的隐性遗传组成在始祖动物基因组中分布不均时，近交衰退的程度在不同始祖动物的后代之间可能不同。俾路支羊的繁殖记录，包括出生时产仔数 (LSB)、断奶时体重 (LSW)、平均出生体重/出生羔羊 (LMWLB)、平均体重/断奶羔羊 (LMWLW)、出生时/母羊产羔总重 (TLWB) ) 和断奶/母羊产羔总重 (TLWW) 用于检查始祖动物之间近交衰退的异质性。基于谱系的近亲繁殖系数按比例分配为来自始祖动物的成分和来自非始祖动物的孟德尔贡献。使用两种方法来评估近亲繁殖的影响：四种主要始祖动物的整体近亲繁殖系数或部分近亲繁殖作为统计模型中包含的可能协变量。在评估的性状中，近交对 LMWLB、LMWLW 和 TLWW 有影响，近交每增加 1%，分别减少 -8、-48 和 -95 g。由于始祖动物的部分近交系数的性状线性回归具有不同的幅度，范围在 -0.12 和 +0.128 之间。对于 LSB、LMWLB 和 TLWW，始祖动物对近交衰退的贡献存在异质性。这些结果表明，在创始动物基因组中隐性遗传组成分布不均匀，或者不同创始品系之间不利等位基因的选择压力存在差异。