Epsilon Archive for Student Projects

Abstract

It is common knowledge that pigs are used to search for truffles and that their sense of smell is well developed. Still, there is not much research about pigs’ sense of smell and therefore the aim of this study is to describe which behaviours the pigs perform immediately when exposed to scent enrichment. This study was part of a larger research project about pig olfaction and scent enrichment for pigs. According to Swedish legislation, pigs must have enrichment, to ensure that they have an opportunity to perform their natural behaviours, and thereby reduce problematic behaviours such as tail biting. Before the test started, all pigs were habituated to the experimental pens and equipment. The test included twelve odours (aniseed, blood orange, vanilla, apple, cinnamon bark, musk, pine, jasmine, ginger, thyme, lavender, and cedar wood) and one control (distilled water). Each odour was attached to the test box and was available 3*1 minute, then removed for two minutes. Each test day three scents were tested three times each (total of nine presentations). The whole operation was video recorded, and the immediate behavioural reaction of the pigs was observed. One part of the study was to observe pigs’ behaviour during the first ten seconds. A reaction scale (0-5, where 0 is no reaction and 5 is the strongest reaction) was developed to study the pig’s immediate reaction towards the odours when detecting it for the first time. The average reaction score for the pigs when presented with the odour was 1.10. Some odours were more popular with the pigs, e.g., aniseed, jasmine, and ginger were sniffed more than all other odours. One of the most frequently observed behaviours was sniffing. In total, sniffing the odour was observed in 36% of the odour presentations. Although tail flicking has only previously been described in relation to discomfort, tail flicking was observed as an immediate reaction to blood orange, cinnamon bark and thyme and was not followed by any backing or fleeing from the odour. This may indicate that tail flicking was an autonomous reaction when the olfactory nerve was stimulated. In conclusion sniffing was the most frequently observed behaviour. One behaviour which may be associated with positive stimulus is biting in the hole, where the odours were presented, meanwhile headshaking can be associated with negative stimulus. The results in this study provide information about pigs’ behaviour related to odour and how scent enrichment can be implemented in the pig industry. These findings will contribute to increased knowledge about pigs with potential to improve their welfare. Further research is required before more conclusions can be drawn regarding pigs’ behaviour when exposed to odours.