Abstract

The key to the adoption of selecting for temperament in animals is the ability to do so in a way that is accurate, easy, and inexpensive. Chute score (CS), exit score (ES), and exit velocity (EV) have been proposed as methods to measure temperament of animals in a production setting. Before using these methods to make selection decisions, their practicality of use and efficiency must be considered. The objectives of this study were to determine whether behavioral scores or values change under repeated and routine management and, if so, assess how such change over time may affect their utility for use in selection programs. Over 3 consecutive years, a factorial design of 2 measurement protocols [frequent (F), infrequent (IN)], and 3 events, each 1 mo apart, was used. The F measurements were collected over 3 consecutive days; IN measurements were collected on d 1 within each event. Twenty predominantly Angus heifer calves, 2-wk post weaning, were randomly assigned to each protocol. Heifers were weighed, calmly moved into a squeeze chute, and their heads caught. A CS was assigned from 1 (docile) to 6 (aggressive) by up to 4 observers. Exit velocity over a distance of 2 m was obtained on release from the chute, and an ES given from 1 (docile) to 5 (aggressive) by the same observers. Data were analyzed with ANOVA using SAS. For all heifers, protocol, event, and their interaction, were compared on d 1. For heifers assigned to F, event, and day within event, were instead fitted. For both models, body weight was included as a covariate, and sire and year were fitted as random effects. Inter-observer reliabilities were calculated using Kendall's coefficients and intra-class correlation using R. Repeatabilities and heritabililties were calculated for a sire model in ASReml. Chute score decreased across events (0.61 ± 0.16; P = 0.04) and days (0.86 ± 0.20; P = 0.02) in F. Exit scores and EV changed less over time. Chute score therefore may be more indicative of acclimation to a novel environment than ES or EV. Inter-observer reliabilities were above 0.7, indicating consistent evaluation among observers, with higher values for ES than CS. Repeatability was high for all measures: 0.88 ± 0.20 for ES, 0.68 ± 0.20 for EV, and 0.62 ± 0.24 for CS. While all methods appear to offer an accurate and repeatable way to quantify and select for temperament in cattle, CS and ES may be preferred due to ease of use. Heifers became calmer with repeated gentle handling. Producers therefore may benefit from allowing cattle a few days to acclimate to new working facilities before assessing docility. This may avoid culling an animal based strictly on its initial response to a novel stimuli. Keywords: acclimation, beef cattle, reliability, temperament

Jamie Parham, Amy Tanner, Mark Wahlberg, William Swecker, Jr, Ronald Lewis

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Biology - Behaviour, , 575, 2018
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