Nest-building behaviour in male rats from three inbred strains: BN/HsdCpb, BDIX/OrIIco and LEW/Mol (2005)

Jegstrup, I. M., Vestergaard, R., Vach, W. et al.

Abstract

It was demonstrated in three inbred strains [BN, BDIX, LEW] of pair-housed male rats that naive animals who never had access to any kind of nesting material do build nests if the correct stimuli are provided. The animals were housed in 48 x 38 x 20 cm large cages with aspen wood chips bedding, each furnished with a roofed wooden nest box measuring 28.5 x 20.5 x 12.5 cm. The box had two entrance holes with a 6 cm diameter on two different sides. Aspen wood wool and autoclaved straw were placed outside the box. The nest was removed and the box along with the two rats transferred to a new cage every two weeks. Additional fresh bedding material and straw was added twice a week, and wood wool once a week. The wooden nest box was machine-washed every two months. All animals built a new nest in the box in the two week period between the cage changing procedure. The animals began with the removal of all aspen bedding material form the nest box. They continued with the collection of straw and wood wool, forming a mat inside the empty nest box. This mat could be several centimeters thick and formed into a cup-shape nest. The actual construction of the nest consisted of fibers of both straw and wood wool, with straw forming a larger part of the nest structure itself.