They have seen the light : 3D light distribution and effects of light intensity on animal welfare in swine husbandry

EU rules for the welfare of pigs define 40 lx for a minimum period of eight hours per day as the minimum standards of light intensity in swine buildings. The aim of this study was to verify if the 40 lx light intensity level requested by EU rules was achieved in naturally vs. artificially illuminated areas of a pig house and to investigate light intensity distribution within the building and the pens. For this purpose, light intensity was continuously monitored in two compartments of a piggery at the height of 1.50 m along the central corridor, according to standard inspections adopted in pig farms. As a second step, light intensity was measured in a three dimensional grid at 5 heights (0 to 1.5 m) in six different positions in the pens to investigate light distribution at the heights of animals and humans. The light intensity level required by EU rules was reached 93±5.65% (9:00 am to 5:00 pm) in the artificially illuminated areas. In pens illuminated only by natural light and without dunging areas, the 40 lx level was never reached, while in pens with dunging areas the 40 lx were reached 83±1.83% (9:00 am to 5:00 pm). Analysis of the 3D distribution of light intensity revealed that the light level remained very low (15 lx) inside the pen.