Ovine Observer

Are wormy sheep worried?

Emily Grant, Murdoch University, WA
Corresponding author:


The general health and wellbeing of sheep in production environments is subject to challenges. Therefore it is important to regularly monitor and assess sheep welfare, but this can be difficult for large-scale enterprises with limited labour.

Intestinal parasites are considered an important challenge for the sheep industry, with poor intestinal health associated with reductions in growth and performance. The current method for detection of parasite burden is faecal egg count (FEC), which can be both disruptive for the sheep and time consuming for the staff. As such, the sheep industry is interested in developing alternative methods for detection of sheep with high intestinal parasitic burdens.

To date, few studies have investigated the application of behavioural analyses for this purpose. Qualitative Behavioural Assessment (QBA) has been proposed as a methodology for assessing behaviour relevant to welfare, one that is naturally suited for on-farm application, being quick, easy to implement and non-disruptive.

The present study explored the application of QBA to investigate the expressive behaviour of sheep with high intestinal parasitic burdens. The hypotheses tested were that (i) sheep with high intestinal parasitic burdens, as indicated by high FEC and anaemia, will exhibit different behavioural expression to those sheep that are healthy (with respect to intestinal parasites), which can be identified using QBA; and (ii) that the behavioural expression of those same sheep would differ following anthelmintic treatment.

Healthy sheep
Sheep with high FEC

Materials and methods

The behaviour of ten Merino sheep in varying conditions of intestinal health, ‘healthy’ (n=5; anthelmintic treatment not required based on FEC) or ‘unhealthy’ (n=5; anthelmintic treatment required based on FEC), were assessed using QBA.

All sheep were selected from the same flock, and the allocation of individuals to treatment group was achieved by FEC and mucous membrane anaemia scores. 

Faecal sampling and subsequent (next day) video footage capture of the ten sheep in the paddock were conducted one week prior to treatment of all animals with an anthelmintic drench, and again two weeks following treatment, such that each sheep was filmed twice: once before treatment and once after.

This footage was compiled into a series of assessment clips (n=20) and presented, at random, to 35 observers for QBA analysis. Observers first generated lists of descriptive terms. The terms were then used to assess the clips, ranging from minimum to maximum expression (i.e. 0-100).

Patterns in behavioural expression perceived by observers using this methodology were identified using principal component analyses. This resulted in the creation of a multidimensional matrix where each animal was represented along the continuum between the descriptive terms that best describe each dimension. Based on the responses of the observers, dimension 1 ranged from unsettled to eager, dimension 2 ranged from rushed to bright and dimension 3 ranged from depressed to careful.

Treatment differences in the behavioural expression of the sheep were analysed using repeated-measures analysis of variance.

Results and discussion

Figure 7 Position of sheep within their treatments on dimension 1 (a), 2 (b) and 3 (c),  before and after treatment intervention * P<0.05, *** P<0.001

There was good agreement (P<0.001) between the observers in their assessments of the behavioural expression of the sheep.

The three main dimensions explained 25%, 17% and 10% of the variation in scores attributed to individual sheep, respectively.

In support of the hypotheses, significant differences in behavioural expression were identified on the three dimensions (Figure 7).

Observers were able to distinguish differences in behavioural expression between the treatments, with ‘unhealthy’ sheep described as more ‘unsettled’ when compared to ‘healthy’ sheep, which were described as more ‘eager’ along dimension 1 (P<0.05).

Anthelmintic treatment altered the behavioural expression of the sheep. Specifically, there was a significant effect on dimension 3 (P<0.05), where both ‘healthy’ and ‘unhealthy’ sheep were described by the observers as having a less ‘depressed’ demeanour following anthelmintic treatment.

On dimension 2 the ‘healthy’ sheep were described as more ‘bright/observant’ following anthelmintic treatment (P<0.001) intervention. 


These findings demonstrate that sheep with different intestinal parasitic burdens display differences in behavioural expression, and these differences can be identified using the QBA methodology.

Therefore, not only does the potential exist for QBA to be used as a tool to help distinguish sheep with compromised intestinal health that need treatment, but it may also be used to monitor animals following treatment to test for the effectiveness of the anthelmintic.