Effect of different light intensities on the activity patterns of growing-finishing pigs

Research output: Chapter in Book/Report/Conference proceedingAbstract


Light is known to be an important environmental factor regulating the secretion of melatonin. This hormone is synthetised in absence of light to trigger the circadian sleep/wake cycle and therefore the diurnal patterns of activity. EU welfare regulation imposes a minimal threshold for light intensity in pig barns of 40 lux. However, knowledge about pigs’ behavioural response to light intensity is limited and so far, literature shows mainly studies of light intensities up to 600 lux. The objectives of this study were to assess if light intensity impacts pigs’ activity and how pigs adapt their activity patterns over time. Four artificial light treatments were tested in two batches of growing-finishing pigs (2x16 pens with 7 pigs each). Light intensity at pig eye level was low (46 lux), medium (203 lux) or high (988 lux) with a homogeneous light distribution within each pen. A fourth treatment consisted of a spatial gradient of intensity ranging from 72 lux in the front part of the pen to 331 lux in the back. The photoperiod (11L:13D) and light spectrum provided by customizable LED-based luminaires were similar amongst treatments. Video data were collected on the sixth and tenth week of the growing finishing phase. Active behaviour was observed through scan sampling every 20 minutes for 24 hours and pigs were considered active when they were moving, interacting with their environment or with pen mates either in standing, sitting or lying position. For each scan and each pen, a group activity score in percentage was obtained by dividing the amount of pigs active over the amount of animals present in each pen. Differences in group activity per light treatment were tested using the Kruskal-Wallis test. Preliminary results based on batch 1 demonstrate that group activity did not differ between intensity treatments (p=0.59). In accordance with literature, pigs became less active over time with a group activity of 23.4% in week 6 compared to 19.0% active pigs in week 10 (p<0.001). Graphical representation of activity patterns show a clear diurnal rhythm with most activity occurring during light period. It seems that pigs exposed to low light intensity were active earlier compared to higher intensities, however more data and further analysis are needed to confirm this. In conclusion, preliminary results show that pigs’ active behaviour decreases with time, but light intensity does not clearly affect group activity. Also, pigs exposed to dim light seem active earlier in the morning
Original languageEnglish
Title of host publication 55th Congress of the ISAE
Subtitle of host publicationAnimal Behaviour and Beyond
PublisherInternational Society for Applied Ethology (ISAE)
Number of pages1
Publication statusPublished - 5 Sept 2022
Event55th Congress of the International Society of Applied Ethology (2022): Animal Behaviour and Beyond - Hotel Metropol, Ohrid, North Macedonia
Duration: 4 Sept 20228 Sept 2022


Conference55th Congress of the International Society of Applied Ethology (2022)
Abbreviated titleISAE2022
Country/TerritoryNorth Macedonia


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