Animal behaviour is described as everything that the animal does, in response to external stimuli in the environment and also in response to internal stimuli such as disease, hunger, thirst and pain (Manning and Dawkins, 1998). Some authors give more
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importance to the perception by the animal of its environment than to the actual environmental stimuli themselves. Pritchard et al. (2005) described behaviour as the expression of an animal's perception of its environment, and how it interacts with it.
External stimuli, such as noise, vibration and human handling that occur during transport and slaughter can affect how the neuro-endocrine system responds (von Borell, 2001), which in turn can play a role in the behaviour of the animal (Yousef, 1988). In addition, if an animal has a negative perception of its environment (e.g. previous negative experience during transport), there is more chance of it reacting with a fight or flight response
(Popescu and Diugan, 2012). Therefore, the behaviour of an animal can be used as an effective tool to assess welfare (Beaver, 2010).
In order to use behaviour as an assessment variable, a good understanding of species-specific behaviour is important. In the case of horses destined for slaughter, observing behaviour during transportation and slaughter can provide meaningful information about the animals‟ welfare status (Grandin, 2010b). It is essential to capture behaviours that indicate aversion, aggression and difficulty in coping (Broom, 2005). Some of these behaviours could be reluctance to move forward, freezing (reluctance to move due to fear), backing off, running away, vocalizing and biting behaviour (Broom, 2007). Having data on baseline values for these specific behaviours for horses could help create
benchmarks. For example, the frequency of biting behaviour in the lairage (for a
particular time period) may provide a benchmark level, to determine which management strategies are effective in reducing the frequency of biting, which has been associated with the prevalence of wounds in slaughter horses.
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Unpleasant sensations or feelings due to starvation (hunger) and dehydration (thirst) can be expressed by animals as behaviour (increased motivation to eat and drink) and hence in some circumstances these behavioural expressions, such as eating or drinking, can be quantified and used as assessments of these feelings. To understand the effect of feed restriction in animals, it is easier to use behaviour variables to assess welfare
(Appleby and Lawrence, 1987) rather than measuring physiological indicators for hunger.
Some of the common behaviour states or events which have been quantified to assess welfare in previous studies are;
The frequency and duration of behaviours that may indicate pleasure (play behaviour), fear, discomfort and social disturbance (Cameron et al., 2008;
Hockenhull and Creighton, 2012).
The duration of normal behaviours such as eating and drinking so that evaluation can be performed for any abnormal increase or decrease in time spent (Ray and Roubicek, 1971).
The frequency of behaviours which indicate aversion such as freezing and backing off (Fraser, 2010).
The emergence of any redirected behaviours or displacement behaviour or stereotypic behaviour (Cooper and Albentosa, 2005)
An extensive study involving many countries observing equines managed under different welfare scenarios showed a significant relationship between specific behaviour and conditions that indicate poor welfare (Burn et al., 2010). This study established that behaviour measures of unresponsiveness to human approach and other stimuli were
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associated with poor body condition, abnormal mucous membrane colour, faecal soiling, eye abnormalities and injuries.
1.2.3.1. Assessment of fear
Fear is defined as the “reaction to the perception of actual danger” (Forkman et al., 2007) and hence expressed as a change in behaviour that could be used for assessment of welfare. Fear in horses during transport and slaughter could be due to an innate response (isolation fear), novelty, learned negative experiences and looking at or sensing the fear of others (Gregory, 2004). Fear negatively affects horses, particularly those that are not habituated or acclimatized enough with experiences during transport. The processes associated with slaughter generally comprise events such as novel and noisy conditions during lairage and stunning, which creates fear in the horses. Some other factors of transport and slaughter that can induce fear are inappropriate handling during transport and slaughter, unsuitable flooring in the slaughter plant or transport vehicles which can be slippery, and inappropriate lighting arrangements (Grandin, 2010a).
Even though habituation can reduce the magnitude of the fear response during transport, domestic horses respond to perceived threats and novelty in much the same way as their wild ancestors (Christensen et al., 2005). This is because the horse's sensory system (vision, hearing, touch and smell) may have been adapted to facilitate early detection of danger (Saslow, 2002). Studies on horses have shown that three of these sensory systems (visual, olfactory and auditory) responded to novel stimulus (predator odour) and are associated with negative emotive states and changes in behaviour such as sniffing and vigilance (Christensen and Rundgren, 2008).
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An ethogram (catalogue of behaviours typically exhibited by an animal) recorded during transport of horses, indicated that vocalisation, kicking, pawing, stamping,
defecating and urination could be associated with fear (Waran et al., 1996). Even though defecation and urination are normal physiological functions, an increase in frequency of these behaviours indicate fear and hence could be used as an indicator of negative emotional state. Quantitative measurement of these behaviours can be used to assess welfare.
1.2.3.2. Assessment of discomfort
Transport and slaughter procedures of horses, if not managed carefully, have a high risk of causing discomfort. Thermal and physical discomfort as a consequence of extremes of temperature, inadequate ventilation and space, vibration, acceleration and motion (Cockram, 2007) are recorded during the transport of food animals. Discomfort can be caused due to hunger and thirst, particularly during long distance transport (with high stocking density without adequate free access to food and water). Measuring
behaviours or events such as slips, falls, stumbles and collisions of horses with each other or with any part of the vehicle (Knowles et al., 2010), can provide indirect information about the levels of discomfort that the animal may be experiencing. Some other
behavioural indicators of discomfort previously studied during transport of horses are vocalization, attempts to escape, kicking and struggling (Fazio and Ferlazzo, 2003).
Observation for these behaviours in the lairage could also be used to identify and quantify discomfort. Anecdotal incidences of increased aggressive behaviour due to hunger and thirst have been reported in horses (Houpt, 1981).
25 1.2.3.3. Assessment of social disturbance
Isolation from other horses, grouping with unfamiliar horses and mixing of sexes during transport can all be risk factors for poor welfare by creating social disturbance,
sometimes causing injuries or minor stressful situations. Isolation during transport can induce fear behaviour such as pawing and sniffing in young inexperienced horses and reduced feeding behaviour (Kay and Hall, 2009). Knowles et al. (2010) reported that when semi-feral ponies were transported in groups of four (small group size), the level of aggression was less than in groups of eight (large group size). In this study, apart from group size, stocking density also had a significant association with aggressive behaviours, such as bites, kicks, snaps and ears kept facing backwards. When stocking density was increased, the incidence of aggressive behaviour also increased. Stallions can be more aggressive than geldings and mares and hence mixing of sexes during transport should be avoided. In order to assess social disturbance, recording behaviours which indicate aggression among horses (kicking and biting), and behaviour which indicates fear (pawing, sniffing etc) are potentially useful variables.