One of the key factors affecting achievement of good reproductive skills within the microclimatic conditions is lighting. The environment in which animals are kept can be defined as an overall influence of external physical, chemical and biological factors, all of them being among those substantially affecting the animal welfare. The lighting parameters play a significant role. Light intensity which is evaluated in this experiment was conducted at weekly intervals at ISK Velke Mezirici from March 2012 to March 2013. The experiment included such breeds of pigs as Duroc, Danish Duroc and Landrace. Light intensity was evaluated in relation to parameters of sperm quality, namely: sperm motility (%), semen volume (ml), sperm concentration (thousand/mm(3)) and the percentage of sperm with pathological changes (%). The analysis of collected data showed statistically a significant light effect on the ejaculate quality (P=0.01). With an increase of light intensity (65.7 lx), the volume and portion of pathological changes decreased (to 231.3 ml from 279.7 ml and 8.7 % from 9.6%), while the concentration has risen (426.8 thousand/mm(3) from 346.2 thousand/mm(3)) in opposite to lower level of light intensity (52.3 lx).
