Gеnetic implications of inbreeding in farm animals: evidence from a case of cyclopia
Abstract
Inbreeding, or close-relative mating, is a traditional and highly effective tool in the selection of farm animals, primarily aimed at fixing desirable economic traits. However, uncontrolled and intensive inbreeding carries significant genetic risks that fundamentally alter the genotypic structure of a population. The primary genetic consequence is a sharp increase in homozygosity, which inevitably leads to the expression of harmful, sublethal, or lethal recessive mutations. This phenomenon, known as inbreeding depression, often severely impairs both biological and economic performance.
This study analyzes the theoretical genetic aspects of inbreeding and the phenomenon of inbreeding depression in the context of commercial animal husbandry. Furthermore, we present a series of clinical cases of severe congenital malformations-namely, cyclopia, holoprosencephaly, and otocephaly - documented in various farm animal species, including horses, sheep/goats, and rabbits. These severe anomalies, often fatal and associated with mutations in key developmental regulatory genes, are used as direct indicators of genetic risk. The described cases provide concrete evidence of the increased vulnerability of populations with a narrow gene pool to the manifestation of rare recessive genetic defects.
The research materials include a review of classical genetic models, statistical data on the prevalence of anomalies, and documented clinical cases, including our own results from full-sibling crossings in rabbits. The results of this integrated analysis underscore the necessity of meticulous genetic monitoring and the implementation of molecular screening in all breeding populations. We recommend maintaining the inbreeding coefficient below 5 – 6 % over five generations, consistently rotating unrelated sires, and systematically excluding known carriers of lethal recessive mutations to mitigate the negative consequences of genetic load.
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