Toward an Ethogram of Heavy Pigs

Behavioural observations of heavy pigs (body weight range 70-160kg) carried out during 5 trials were merged into a dataset to analyse common traits and draft a preliminary ethogram for this neglected animal category. Observations were carried out on videorecordings of collective pens (5 animals/pen) using the scan sampling technique (10 seconds of sampling every 10 minutes). In total, 200 animals and 8448 hours of videos were analysed. Behavioural differences by body weight categories and daily hours (morning vs. afternoon vs. night) were assessed using the Kruskal-Wallis test. Over the 24h, the most represented behaviour was lateral recumbency (60% on average), followed by lateral recumbency (18%), pen exploration (9%) an eating (5%, liquid feed was distributed twice a day). Standing inactive and sitting inactive were observed for less than 3% of the time each, and other behaviours, only sporadically observed due to the sampling technique, included drinking, walking and social interactions. Lateral recumbency was more frequent during the night, while sternal recumbency, pen exploration and standing inactive were observed more in the afternoon (P<0.001 for all differences). Concerning body weight, as animals grew from light (70-100kg) to intermediate (100-130kg) and then to heavy (130-160kg), exploring, standing inactive and sternal recumbency decreased, while lateral recumbency increased (for all behaviours, heavy pigs significantly differed from lighter categories, P<0.001). Pending analysis on larger datasets, these results highlight the typical behaviour of heavy pigs and the importance of providing adequate space and conditions for comfortable resting (i.e., lateral recumbency) in terms of animal welfare.