BEHAVIOURAL CONSEQUENCES OF IVC CAGES ON MALE AND FEMALE C57BL/6J MICE

摘要

Over the past decade, technology for housing laboratory animals has continued to evolve. Initially, to protect mice and workers from infections, filter covers (i.e. micro-isolators) were introduced on static conventional cages (i.e. filter-top cages: FILTER). However, as CO2 and NH3 levels rise significantly in these cages within a short time (Lipman et al., 1992; Krohn and Hansen, 2002), more recent developments have resulted in the employment of individually ventilated cage (IVC) systems. These IVC systems produce a cage environment different to FILTER in regard to airflow, noise levels within the cage, and frequency of cage changes (Mineur and Crusio, 2009). For example, air changes ranging from 25 to 120 times per hour (Huerkamp and Lehner, 1994; Perkins and Lipman, 1996) and air speeds of at minimum 0.2 m/s at the animal level (Wu et al., 1985; Corning and Lipman, 1992; Lipman, 1999) have been reported for IVC cages. Furthermore, IVC designs vary significantly in terms of cage size, shape, internal structural complexity and the way the air is forced or drawn through the cage. Variations such as inlet vent size and position may impact significantly on air speeds within cages and the location of fans in positively ventilated IVCs can impact on sound in the cages. These differences across IVC systems are significant: Krohn et al. (2003) found that rats kept in cages with high air changing rates developed a place aversion to those cage environments.