A review on the effect of light-thermal-humidity environment in sow houses on sow reproduction and welfare.

The environment in sow houses is the key to restrict sow production due to its significant effect on sow growth and reproduction. In this article, the effect of light, thermal and light-thermal-humidity environment in sow houses is systematically reviewed for sow reproduction and welfare according to the existing literature. The results show the optimal ambient temperature range for sows is approximately 16-22°C, as well as the lowest and highest critical temperature are 16 and 27°C respectively. Meanwhile, the increase of relative humidity from 50% to 70% is equivalent to the increase of effective temperature by 0.9°C in sow houses. In addition, the evaluation indexes are summarized to the future research direction is proposed according to the reviewed results. It can be concluded that the current research mainly focuses on the effect mechanism of light-thermal-humidity environment on sow growth and reproductive performance, as well as the optimal regulation range of light-thermal-humidity environment. In particular, it is a popular topic to further study the effect of light-thermal-humidity environment on the genetic material of sows, as well as metabolic parameters and body composition of their offspring. The above conclusions can contribute to guiding the regulation of light-thermal-humidity environment in sow houses and improving the sow welfare.