Qualitative behavioural assessment of the motivation for feed in sheep in response to altered body condition score

Qualitative behavioural assessment (QBA) has been used to quantify the expressive behaviour of animals, and operant tests have been used to quantify measures of behavioural need. In this study we compared measures of behavioural expression and behaviour in operant tests. We examined the behavioural expression of pregnant ewes of body condition score (BCS) 2 and 3. The ewes were exposed to a feed motivation test in which they received a food reward. Pregnant ewes (48–70 days gestation) were assessed during a food motivation test after they had been maintained at BCS 3 (n = 7) or given a decreasing plane of nutrition that resulted in slow loss of 1 BCS unit (over 10–12 weeks; n = 7) or a fast loss of 1 BCS unit (over 4–6 weeks; n = 7). The feed motivation test involved ewes having the opportunity to approach a food reward and then being moved a given distance away from the reward by an automatic gate; they could then subsequently return to the feeder. Continuous video footage of each ewe during one cycle of the gate (approaching and returning from the food reward) was shown in random order to 11 observers who used their own descriptive terms (free-choice profiling methodology; FCP) to score the animals using QBA. Data of the assessment were analysed with generalised Procrustes analysis (GPA), a multivariate statistical technique associated with FCP. The research group also quantified the feeding behaviour of sheep in the same clips. These behaviours included how sheep approached the feeder, behaviours exhibited at the feeder, and how sheep returned from the feeder. There was consensus amongst observers in terms of their assessment of behavioural expression of the sheep (P < 0.001). The GPA found three main dimensions of assessed behavioural expression in the sheep, which together explained 44% of the variation observed. GPA dimension 1 differed between the three treatment groups (P < 0.05): ewes maintained at BCS 3 scored low on GPA dimension 1 (i.e. were described as more calm/bored/comfortable) compared with ewes that had a slow declining BCS (described as more interested/anxious/excited). GPA dimension 2 scores were not significantly different between treatment groups. However, quantitative behaviours exhibited by sheep during the clips were correlated with qualitative behavioural assessments made by the observers. Animals that spent more time ‘sniffing and looking for more feed’ were attributed lower GPA 2 scores (described as more hungry/searching/excited) (P < 0.05), and animals that ‘did not walk directly to the food reward (but stopped along the way)’ were attributed significantly higher GPA 2 scores (more curious/intimidated/uneasy) (P < 0.01). GPA dimension 3 scores also did not differ between the treatment groups; however, sheep that had a higher number of feeding events during the entire 23-h feed motivation test were attributed lower GPA dimension 3 scores (they were described as more hungry/bold/interested) (P < 0.05), and sheep that consumed a larger amount of the feed reward were attributed higher GPA dimension 3 scores (more curious/concerned/reserved) (P < 0.05). We conclude that QBA is a valuable method of assessing sheep behavioural expression under the conditions tested, in that it provided an integrative characterisation of sheep behavioural expression that was in agreement with quantitative behavioural measures of feeding.