The effect of light intensity on the breeding and development of rats and golden hamsters (1969)

Weihe, W. H., Schidlow, J., Strittmatter, J.

Abstract

It was noticed that animals subjected to an illumination of 2000 lux were tame and playful with handling, while those at lower light intensities resisted handling and tried to bite when vaginal smear was taken. ... The weight of some important organs, such as adrenals and testes, and also the breeding performance, showed a significant relationship to light intensity which was not seen in the hamster. ... For practical purposes it can be inferred, that, to obtain uniform results, rooms for rat breeding need to be more equally illuminated. ... The different light intensities from 1 to 5,000 lx, that we have found in animal rooms, may have some effect on the responses of animals to experimental procedures.