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A B S T R A C TIn general, is said that functional traits have a positive genetic correlation with conformation in horses but, this hypothesis has never been investigated in the Brazilian Campolina breed. We aimed to estimate genetic parameters (heritabilities and genetic correlations) for these traits based on genealogical records from 107,951 animals, in which 43,159 were phenotyped. A total of 16 morphological traits (MT); one gaits score (GtS) and two traits related to conformation harmony (CH), were simultaneously analysed under a Bayesian multi-trait model framework. Genetic trends were estimated over the years of birth for animals born between 1951 and 2016. MT were all genetically positively associated (from 0.05 to 0.98). CH traits presented positive and negative genetic correlations, but all favourable to the selection goals. GtS was negatively associated with all MT, except for Chest Width (0.08). CH and GtS presented lower positive genetic correlation (0.10 and 0.01, for the ratio between Height at Withers and Height at Back, and ratio of Back-Loins Length over Body Length, respectively). Observed results indicated the existence of sufficient additive genetic variance (heritability estimates ranged from 0.07 to 0.43) for the studied traits, benefiting the implementation of a breeding program, if the desired is to select animals for morphology or gaits. All genetic trends were favorable despite of the phenotypic selection in the Campolina breed. These trends presented low regression coefficients, but the increase on average predicted breeding values for the investigated period was 137.9%.

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The objective of the present study was to investigate the impact of considering population structure in cow genotyping strategies over the accuracy and bias of genomic predictions. A small dairy cattle population was simulated to address these objectives. Based on four main traditional designs (random, top‐yield, extreme‐yield and top‐accuracy cows), different numbers (1,000; 2,000 and 5,000) of cows were sampled and included in the reference population. Traditional designs were replicated considering or not population structure and compared among and with a reference population containing only bulls. The inclusion of cows increased accuracy in all scenarios compared with using only bulls. Scenarios accounting for population structure when choosing cows to the reference population slightly outperformed their traditional versions by yielding higher accuracy and lower bias in genomic predictions. Building a cow‐based reference population from groups of related individuals considering the frequency of individuals from those same groups in the validation population yielded promising results with applications on selection for expensive‐ or difficult‐to‐measure traits. Methods here presented may be easily implemented in both new or already established breeding programs, as they improved prediction and reduced bias in genomic evaluations while demanding no additional costs.

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