Effect of the individual coefficients of inbreeding and grading calculated at different ancestral generations of pedigree regarding body proportions of Shagya horses

摘要

The objectives of the present study were to investigate the effect of the inbreeding and the rate of genetic plasma from Arabian breed regarding the body proportions in real Shagya population. The analyses of variance of the indexes for bone system development, compactness, massiveness and chest development and estimations of the levels of factors were made by regression, classification and mixed linear models. The individual inbreeding coefficient and grading induced a considerable variance regarding the body proportions during the study. Their use as linear and non-linear regressions or classification factors in the structure of linear models led to a considerably reduction of the rate of an unexplained variance. The nonlinear effect of the inbreeding was statistically proved regarding the chest index at 6-months of age, the massiveness at 1-year of age, and the bone system development and the body compactness at 3-years of age. The grading calculated in the Vth and VIth generation of pedigrees was an important source of variation in the late postnatal growth concerning the chest and bone system development. The grading in the IVth generation of pedigrees was significant for a description of the variance of compactness. Synergetic effect was established of the linear and quadratic regressions for the grading calculated in the Vth and VIth generation of pedigrees in the chest index. The interactions between the grading from the studied generations of pedigrees were sources of a specific variance regarding the bone system development and the interactions between the grading and inbreeding calculated in the VIth generation of pedigrees induced a variety regarding the massiveness. It was established an increased sensitiveness of the massiveness to higher levels of complex inbreeding increasing the grading.