Assessment of inbreeding depression for body measurements in Spanish Purebred (Andalusian) horses

Our aim was to ascertain inbreeding depression in the Spanish Purebred horses for eight body measurements. A total of 16,472 individuals were measured for height at withers, height at chest, leg length, body length, width of chest, heart girth circumference, knee perimeter and cannon bone circumference. Three different multivariate animal models including, respectively, no measure of inbreeding, individual inbreeding coefficients (Fi) or individual increase in inbreeding coefficients (ΔFi) as linear covariates were used. Significant inbreeding depression was assessed. Even though the models including measures of inbreeding fitted better with data, no effect on estimates of genetic parameters was assessed. However, the inclusion of inbreeding measures affected the ranking order according to the Expected Breeding Values (EBV). Due to the better fit with data and nice properties (the adjustment of individual inbreeding coefficients with the pedigree depth and linear behaviour) the use of ΔFi in the evaluation models can be recommended for morphological traits in horses.

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