A NOTE ON THE EFFECT OF GESTATION HOUSING ENVIRONMENT ON APPROACH TEST MEASURES IN GILTS

Authors: Marchant, Jeremy; BRADSHAW, R - UNIV OF CAMBRIDGE, UK; MARCHANT FORDE, R - DEMONTFORT UNIV, UK; BROOM, D - UNIV OF CAMBRIDGE UK

Submitted to: Applied Animal Behaviour Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2002
Publication Date: 3/1/2003
Citation: MARCHANT FORDE, J.N., BRADSHAW, R.H., MARCHANT FORDE, R.M., BROOM, D.M. A NOTE ON THE EFFECT OF GESTATION HOUSING ENVIRONMENT ON APPROACH TEST MEASURES IN GILTS. APPLIED ANIMAL BEHAVIOR SCIENCE. 2003.

Interpretive Summary: The human approach test has been used to assess an animal's generalized fearfulness of humans. The approach behaviour of the pig is likely to be greatly influenced by its familiarity with the test environment and the test may simply reflect the pig's level of motivation to explore the arena rather than provide a measure of the specific fear response to a human who is behaving in an atypical fashion. The approach behaviour of the pig may vary in relation to the relative difference between the test arena and its usual home environment and the relative quantity and quality of human contact within that home environment. Animals coming from an enriched system into a barren test arena may be behaviorally inhibited due to fear of novelty or may show increased activity. Likewise, animals that receive regular contact with humans or that have learnt to associate humans with food delivery may either be quick to approach the human or may avoid a human behaving atypically. The aims of this study were to investigate whether short-term exposure to gestation housing systems, which varied in terms of physical environment and quantity and quality of human contact, influenced behavioural and physiological measures during a standard human approach test. Gilts were exposed to different gestation housing systems, one indoors and one outdoors, for only 30-44 days before testing in an indoor test pen. We found that gilts coming from the outdoor system performed less exploratory behavior and had much lower heart rates than those coming from the indoor system. Outdoor gilts were also slower to approach the human but then made contact quicker. The outdoor gilts, with a more diverse experience, are hesitant in certain novel situations perhaps because of better ability to recognise and evaluate potentially risky situations. Exploratory behavior was lower in outdoor pigs when the human was present and were slower to approach, perhaps indicating a fear-related reduction in exploration. However, once they had overcome this apparent unwillingness to approach, the positive association between the human and food meant that physical contact occurred quicker. We therefore showed that short-term exposure to different housing systems that varied in physical environment and quantity and quality of human contact, did indeed influence behavioural and physiological measures during a human approach test. This means that producers should be aware that an animal's behavior towards them can be influenced quite quickly by a change in housing and husbandry. Also, for scientists using this type of test, the interpretation of the results should include consideration of behavioural inhibition due to fear of novelty or recognition of an unusual situation and not just as a quantification of the extent of fear of humans.

Technical Abstract: The aims of this study were to investigate whether fairly short-term exposure to gestation housing systems, which varied in physical environment and human contact, influenced behavioural and physiological measures during a human approach test. Twenty-four Large White x Landrace gilts were initially subject to identical human contact and daily husbandry. Forty-two days after service, the gilts were randomly assigned to either an indoor housing system or an outdoor housing system, which differed in the amount of human contact and daily husbandry. The indoor system used an electronic sow feeder and human contact was centered on cleaning out. The outdoor system had access to pasture and human contact was centered on feeding. The human approach test was carried out on all gilts 30 to 44 days after entry to the gestation system. At testing, each individual was fitted with heart rate monitor and then moved into a test arena. After 2 min an unfamiliar human entered the pen and stood motionless for 3 min against one wall and then approached the gilt and touched her snout. Throughout the experimental period, behaviour and sound within the test arena were recorded continuously. During the 2 min familiarisation period, outdoor gilts had lower heart rates (108.2 bpm v. 123.7 bpm, p<0.05) and tended to perform fewer short vocalisations (0.5 min-1 v. 3.4 min-1, p<0.1). Outdoor-housed gilts also carried out less locomotor behaviour (2.2 sections crossed min-1 v. 4.0 sections crossed min-1, p<0.05) and tended to perform fewer short vocalisations (0.5 min-1 v. 3.4 min-1, p<0.1) over the 3 min test period. Outdoor gilts tended to be slower to approach within 0.5m of the human (37.5s v. 20.2s, p<0.1) but they then took less extra time to make physical contact (3.5s v. 27.8s, p<0.1). Mean heart rate was significantly lower in outdoor sows over the whole 3 min period (99.5 bpm vs 115.5 bpm, p<0.05). The results demonstrate that short-term exposure to different housing systems that varied in physical environment and quantity and quality of human contact, did influence behavioural and physiological measures during a standard human approach test. Differences in mean heart rate were probably due to the fact that outdoor-housed sows could carry out a greater amount of activity and thus develop greater fitness than the indoor sows. Differences in investigatory and approach behaviour may indicate that initially, the outdoor gilts showed behavioural inhibition due to a greater appreciation of the unusual aspects of the situation and were thus slower to approach the human. However, once they had overcome this apparent unwillingness to approach, the positive association between the human and food, meant that physical contact occurred quicker. The interpretation of approach test results should include consideration of behavioural inhibition due to fear of novelty or recognition of an unusual situation and not just as a quantification of the extent of fear of humans.