Blood collection has negligible impact on scoring temperament in Angus-based weaned calves

•Age of calf at scoring is not required when modeling the same cohort.•Evaluation sequence is a type of temperament trait.•Exclude evaluation sequence from other temperament traits’ statistical models.•Blood collection has negligible impact on 16 temperament scoring methods. Temperament scoring typically occurs at the same time as vaccinations, germplasm collection, or both. Little is known about the impact of these procedures with scoring temperament. The objective was to determine the impact of blood collection (jugular venipuncture), representing a momentarily painful procedure, on different measures of temperament in weaning age calves. The hypothesis is blood collection will have little to no impact on temperament assessment. Calves of weaning age (n == 420) were sired by Angus bulls and out of Angus-influenced commercial cows. Subjective methods included temperament score (1 to 5 scale, with 3 removed; 1 calm or docile and 5 wild or aggressive) and qualitative behavior assessment attributes of active, agitated, apathetic, attentive, calm, curious, distressed, fearful, happy, irritated, positively occupied, and relaxed (each scored on a 136 mm horizontal line with left equal to no expression and right equal to full expression). Objective scoring was captured by recording multiple weights on a four-platform standing scale with the standard deviation of weight over a specific time interval and its coefficient of variation as measures of temperament. During collection, calves were randomly assigned into before (scored before blood draw) and after (scored after blood draw) groups in sets of 5 as they came through the working facility. Traits were modeled using fixed effects of evaluation day (n == 2), blood collection group (BCG; n == 2), interaction of day and BCG (n == 4), sex of calf (n == 2), and evaluator (n == 4 per method; subjective methods only) using an animal model based on pedigree and accounting for repeated measures using permanent environment variance method. The use of sequence of evaluation nested within day (SEQ) or age of calf (in days) were also assessed as covariates. Age at scoring was not impactful for modeling temperament traits and was not included in further analyses. Inclusion of the SEQ covariate was significant for 11 of 16 scoring methods (68.75%). Its inclusion resulted in lower estimates of additive genetic variation for 10 of 16 traits, suggesting it may be a temperament trait confounded with those analyzed and was exclude