Does the avoidance distance test at the feed barrier have scientific validity for evaluating reactivity to humans in Limousin breeding bulls?

Abstract

Testing beef bull reactivity to humans is a key challenge for improving beef cattle reactions to handling, but the process can be dangerous and requires skill in cattle handling. Testing avoidance distance at the feed barrier (ADF) would be a safer option than test procedures involving exposure to free moving animals. Here we tested ADF for test re-test consistency one week apart and for convergent validity with three other tests involving humans where bulls were free to move. We also tested the relationship between ADF score and growth performances. This observational study used 115 Limousin bulls evaluated on-farm around weaning (8 months) and at the French national evaluation and qualification station for Limousin-breed young bulls, where they were housed from 10 to 15 months of age for a period of control. Qualitative on-farm behavioural scores (BeF), on-station behavioural scores (BeS) and on-station docility scores (Do) were collected during the routine pedigree bull selection process. Three repetitions of the ADF test were performed, in three weeks before the end of the period of control. Standardised 120-day and 400-day weights were calculated and correlated to behavioural scores. ADF showed moderate consistency through the three repetitions (overall intraclass correlation coefficient=0.54). Mixed-effect ordinal logistic regressions were performed to evaluate the links between ADF score and other behavioural data. ADF score was positively related to other scores collected on-station (ADF–BeS, p<0.01; ADF–Do, p<0.05). Animals with lower ADF scores also had heavier predicted 120-day and 400-day weights (p<0.01). Our results suggests that ADF shows consistency with other tests involving humans and is related to key predicted weight outcomes at genetic selection. The ADF test emerges as a promising option for phenotyping individual responsiveness to humans.