Genetic parameters of three methods of temperament evaluation of Brahman calves 1

Abstract

The objective of this study was to estimate the heritability of 3 measures of temperament in Brahman and Brahman-influenced calves (n = 1,209). Individual animal pen scores (PS) were determined by a trained observer who evaluated groups of 5 or 4 calves at a time for willingness to be approached by a human. Exit velocity (EV) was the rate (m/s) at which each calf exited a squeeze chute. Temperament score (TS) was calculated individually as (PS + EV)/2. Temperament was evaluated at 5 different times of record (28 d preweaning, weaning, 28 d postweaning, 56 d postweaning, and yearling). Contemporary groups (n = 34) comprised calves of the same sex born in the same season of the same year. There were an average of 36 calves per contemporary group and group size ranged from 3 to 78 calves. Average weaning age (186 d) ranged from 105 to 304 d. Calves were born from 2002 through 2012. Random effects included additive genetic and the permanent environmental variance. The fixed effects analyzed were age of dam, sex of calf, contemporary group, fraction of Brahman (2 levels: 1 and 0.5), age of calf at record, and weaning age. At weaning, the mean PS was 2.68 ± 0.1, the mean EV was 2.41 ± 0.1, and the mean TS was 2.48 ± 0.1. The PS was affected by fraction of Brahman (P = 0.034) and tended to be affected by age of dam (P = 0.06). The EV was affected by contemporary group (P < 0.001) and tended to be affected by weaning age (P = 0.074). Contemporary group affected TS (P < 0.001). All 3 methods of temperament evaluation were affected by time of record (P < 0.001). The regression coefficients for PS, EV, and TS were 0.0023 ± 0.0014, 0.0022 ± 0.0012, and 0.0015 ± 0.0012 m·s(-1)·d(-1) of age, respectively. Estimates of maternal genetic effects were always 0 and omitted from final models. Estimates of heritability were 0.27 ± 0.1, 0.49 ± 0.1, and 0.43 ± 0.1 for EV, PS, and TS, respectively. Estimates of permanent environmental variances as proportions of phenotypic variance were 0.33 ± 0.1, 0.23 ± 0.1, and 0.33 ± 0.1 for EV, PS, and TS, respectively. There appears to be sufficient additive genetic variance for selective improvement of temperament characteristics in Brahman cattle.

Genetic evaluation of aspects of temperament in Nellore–Angus calves1,2

“…Increases in weight (weaning weight from approximately 2 mo earlier; weights were not recorded at the time of temperament scoring) were associated with reductions in all temperament scores. This is consistent with regressions of exit velocity or subjective chute scores in heifers after weaning (Elzo et al, 2009;Riley et al, 2010); however, in young calves there may be a positive regression on weight until a certain age, after which increases in weight are again associated with decreases in exit velocity and other evaluations of temperament (Schmidt et al, 2014).…”

Behavioural linear standardized scoring system of the Lidia cattle breed by testing in herd: estimation of genetic parameters

“…; Schmidt et al . ). Higher heritabilities for temperament traits were also found in German Angus (ranged from 0.0 to 0.61) and Simmental cattle (ranged from 0.0 to 0.59) (Gauly et al .…”

“…Even though, some references could be found for cattle temperament traits with heritability values ranging from low to high. For example, for those cattle breeds mainly selected for docility like the Limousin or Brahman breeds, the heritability value estimates ranged from 0.11 to 0.49 (Benhajali et al 2010;Schmidt et al 2014). Higher heritabilities for temperament traits were also found in German Angus (ranged from 0.0 to 0.61) and Simmental cattle (ranged from 0.0 to 0.59) (Gauly et al 2001).…”

Influence of temperament-related genes on live weight traits of Charolais cows

“…Results of Pearson's correlation coefficient in this study were inconsistent with those described in other studies focused on correlating temperament with growth, because all the correlations found here were positive. This finding could be related to the time at which temperament was recorded (Curley et al, 2006;Schmidt et al, 2014). Temperament of animals is usually recorded around weaning time, either pre-or post-weaning.…”