The Influence of Temperament on Body Temperature Response to Handling in Angus Cattle
Previous studies have indicated that cattle with more excitable temperaments exhibit an increased stress response. The objective of this study was to investigate the relationship between temperament traits, handling, and stress-induced hyperthermia (SIH) in beef cattle. Rectal temperatures (TREC, °C) of 60 purebred Angus cattle (30 heifers, 30 steers; 235.2 ± 5.11 kg) were recorded at 20 s intervals from 30 min prior to handling until two hours post handling. All cattle were exposed to a standardized handling procedure consisting of (i) being restrained in a weighing box for 30 s; (ii) being held within the crush for 30 s; and then (iii) being restrained in a head bail for 60 s. Cattle temperaments were evaluated via three traits: (1) agitometer score (AG); (2) crush score (CS); and (3) flight speed (FS) during the handling procedure. Agitometer scores and FS measures were used to describe an AG category (AGCAT) and an FS category (FSCAT) that were used to classify animals into three temperament categories: 1, calm; 2, intermediate; and 3, temperamental. Pearson’s correlation coefficients were used to evaluate the associations between (i) AG, CS, FS, and TREC 30 min prior to entry into the weighing box (T-30) and then at 1 min intervals between time of entry into the weighing box (T0) until 10 min post-weighing (T10); and (ii) the relationship between AG, CS, and FS. The relationship between TREC and temperament traits over the 2.5 h were modeled by using a first-order autoregressive repeated measures model. Flight speed had strong to moderate associations with TREC at T-30 (r ≥ 0.37; p ≤ 0.006) and between T0 and T10 (r ≥ 0.36; p ≤ 0.01). There were moderate associations amongst TREC between T0 and T10 and CS (r ≥ 0.31; p ≤ 0.01). A weak relationship existed with CS (r = 0.16; p = 0.16). There were no associations between AG and TREC at T-30 (r ≥ −0.15; p = 0.84) or between T0 and T10 (r ≤ 0.04; p ≥ 0.4). Rectal temperature, irrespective of sex and temperament traits, was influenced by time (p < 0.0001), and maximum TREC (39.3 ± 0.04 °C) occurred between 4 and 5.7 min after entry into the weighing box. In addition, CS (p = 0.007) influenced TREC in these cattle. There were also time × temperament trait × sex interactions with the CS (p = 0.0003) and FSCAT (p = 0.043) categories; however, time × temperament trait interactions were not statistically significant. Results from this study suggest that cattle with excitable temperaments, as evaluated by FS and CS, have a greater increase in TREC. In addition, these results suggest that a relationship exists between basal TREC and FS and CS. Together, these results highlight that temperament, as assessed by FS and CS, influences both basal TREC and the peak temperature recorded following handling but does not influence the magnitude of change in TREC post handling.
A novel protocol to measure startle magnitude in sheep
Temperament is a trait of interest as it impacts ease of handling, production and reactivity to stressful situations. Excessive behavioural reactivity, as an aspect of temperament, may lead to reduced welfare and stockperson safety. Current tests of behavioural reactivity involve isolating the subject and it can be difficult to differentiate between behavioural responses. We therefore aimed to develop a startle test in sheep which quantified variability in behavioural reactivity whilst addressing the effects of social isolation. The startle response is a consistent universal reaction to sudden and intense stimulation, however, magnitude of startle can be highly variable and may be modulated by affective state. In this study, 60 ewes were allocated into three social groups: isolated; surrounded by six life-sized pictures of sheep or; three conspecifics penned on two sides (total six). Sheep were tested over two days in sets of 10 per treatment. Sheep were confined to a 2.1 m × 1.2 m area, with a bowl of feed at one end, for four minutes (min). Approximately 15 s after the sheep commenced eating, a sudden one sec blast of compressed air was delivered to the face. Tri-axial accelerometers, visual scoring, agitometer scores and body temperature were used to assess the magnitude of the startle response and the pre- and post-startle fear behaviours. In the 15 s pre-startle, isolated sheep spent less time eating (p < 0.001; mean percentage of time: 37.4% vs 71.2% and 83.3%) and were 2-4 times longer in a vigilant state (p < 0.001; mean percentage of time: 38.9% vs 18.2% and 11.3%) than those with pictures and conspecifics respectively. Sheep in the conspecific treatment were 3-4 times faster to return to eating after startle than those in the isolated and picture treatments and there was a tendency for them to spend more time eating (p = 0.09) and less time vigilant (p = 0.09) post-startle. For each measure of startle magnitude (startle force, startle duration or retreat distance) the effect of treatment was not statistically important (p > 0.22), however each measure was positively correlated to time spent vigilant post-startle and there were significant increases in time to return to eating for every one unit increase in each of the startle magnitude measures independent of social treatment. The use of conspecifics did not provide social facilitation or buffering of the startle response. This shows promise as a behavioural reactivity test which can utilise conspecifics to reduce any potential negative effects of social isolation during testing.