engleski

Modeling perspectives in the estimation of inbreeding depression based on genomic information: lessons from the bull fertility

Regression of performance (phenotype) on the individual pedigree inbreeding coefficients has been the standard procedure used to quantify inbreeding depression in humans and animals. We have estimated inbreeding depression for the sperm quality traits (volume, sperm concentration, percentage of viable spermatozoa and motility) in Austrian Fleckvieh bulls with emphases on the comparison of models based on pedigree inbreeding versus models based on various genomic estimates of inbreeding [overall and chromosomal (1-29)] derived from BovineSNP50 BeadChip. Linear mixed models were used with a bull as a random effect and all other effects (age of the bull, semen collector, month and year of collection and number of ejaculates per bull per day), including pedigree or genomic (overall and chromosomwise) inbreeding coefficients (co-variable) as fixed effects. Inbreeding depression was found for the volume and percentage of viable spermatozoa, although between two artificial insemination centers some results were heterogeneous. In general, models based on pedigree were comparable to models based on genomic inbreeding (runs of homozygosity) while models based on individual heterozygosity were inferior. In contrast, for all traits analyzed, models with specific chromosomal inbreeding coefficients outperformed models based on overall genomic and pedigree inbreeding coefficients. While genomic inbreeding coefficients have been shown to be powerful, still much work has left to complete our understanding on architecture and modeling of inbreeding depression.

Inbreeding depression; genomic inbreeding; bull fertility

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