A study of using corncob, aspen shaving, dried water hyacinth and banana midrib as bedding for laboratory mice

Abstract

A study of using corncob, aspen shaving, dried water hyacinth and banana midrib as bedding for laboratory mice. The objective of this study was to evaluate the physical characteristics (i.e., absorbency and surface moisture), the physiological effects and intracage ammonia level of 4 types of beddings in laboratory mice. This study was divided into two parts. In the first part, the fluid absorption properties of these four beddings were studied using measurement of liquid absorption and the surface moisture. The results showed that the volumetric absorbency of aspen shaving was significantly higher than other beddings. While, the surface moisture showed no statistically significant difference among beddings. In the second part, 40 ICR mice were randomly assigned to be housed with each bedding for 4 weeks with 10 mice per group (i.e., 5 mice per cage). Mice were housed in static microisolator cage in which the beddings were changed weekly. Animal health, grimace scale, water and food consumptions, intracage ammonia level and animal body weight were evaluated. At the end of the studsy, blood samples were collected for complete blood count and chemistry profile analysis and organs (i.e., liver, kidneys, foot pad, and nasal passage) were harvested for histopathological study. The results revealed that there was no abnormal clinical sign, distress or external lesions in all mice. Body weight gain and food consumptions were not significantly different among groups. Water consumptions were significantly different among groups. Intracage ammonia levels in the aspen shaving, banana midrib and dried water hyacinth groups were higher than 25 ppm within 3 days after beddings were changed, while intracage ammonia levels in corncob groups was increased above 25 ppm in the corncob group at day 7 after changing bedding. The hematology and blood chemistry parameters in everygroups were normal compare with the reference from the animal vendor and previous studies. Histopathological results showed a higher degree of nasal passage inflammation for mice housed in aspen shaving and banana midrib than that of in corncob. The histopathological lesions of kidney, liver and foot pad were similar among groups of beddings. These results suggest that corncob, aspen shaving, dried water hyacinth and banana midrib may be used as beddings for laboratory mice due to their good absorbency capacity and low physiological effects. The results also indicate that, the bedding should be changed twice per week when using aspen shaving, dried water hyacinth and banana midrib as bedding for mice housing in the static micro isolator cages.