Impact of Blood Collection on Scoring Temperament in Angus-Based Weaned Calves Is Negligible

The objective was to determine if temperament scores were affected by blood sampling of calves. At weaning, Angus-based calves (n = 420) were scored over 2 d in a single year by evaluators for docility score (DS; 1 to 6, 1 is calm), temperament score (TS; 1 to 5, 1 is calm, 3 is excluded), and qualitative behavior assessment (QBA; 12 behavioral attributes assessed for expression using a 136 mm line). Each evaluator was randomly assigned 2 of 3 subjective methods (n = 6, 4 per method). An index value, temperament index (TI), was created using the first principal component of the 12 QBA attributes as an additional score. Novel measurements of activity were quantified using a four platform standing scale measuring weight over time (SD over set number of records; SSD) and adjusting that value for the calf’s total weight (CVSSD). Calves were brought into the working facilities in random groups, where they were assigned in sets of 5 as they entered the chute to a treatment group (blood drawn before vs. after temperament evaluation). In this case, DS was always scored before blood draw and not included in analyses. Subjective traits were analyzed by evaluator (n = 56) or combined datasets (n = 14) to include evaluator as a main effect. As SSD and CVSSD had one observation per calf, they followed models on an evaluator basis (n = 2; 72 total models). An animal model fitting pedigree was used with main effects of collection date, sex, and blood draw within collection date (BLDDRW); fixed covariate of sequence within collection date (SEQ); and random effect of calf. Repeated measures were fitted with an unstructured residual covariance matrix for each calf. When including evaluator effect, BLDDRW tended to be significant for QBA Agitated (P = 0.062), but was not significant for the remaining 13 traits (0.178 ≤ P ≤ 0.904). Tendencies were found for SSD, CVSSD (P = 0.053 each), and evaluator 3’s TS (P = 0.054). Evaluator 1’s QBA Active and 6’s QBA Happy (P = 0.022 and 0.034, respectively) were significant. The remaining 58 models by evaluator were not significant (0.109 ≤ P ≤ 0.983). As significance was often evaluator specific and only a few treatment differences detected in analyses of any trait, it can be concluded that the impact of blood draw on temperament scoring is negligible for calves of similar age and type.