title: Housing experimental rats in solid-based cages with digestible bedding may confound outcomes of nutritional studies.
abstract: BACKGROUND
  Rats used in nutritional studies are often kept in wire-based cages to prevent ingestion of bedding and minimise ingestion of faeces. However, wire-based cages are criticised because of potential negative animal welfare implications. This study investigated the effects of wire and solid-based cages with corncob bedding on large bowel fermentation and microbiota. Rats were group housed in wire or solid-based cages and fed either a low-fibre (LF) diet or a high-fibre (HF) diet composed of resistant starch for 4 weeks.
  
  
  RESULTS
  Bedding material was observed in faeces of rats housed in solid-based cages. Caging type and diet altered large bowel fermentation variables and bacterial populations. Caecal digesta weight was lower in rats fed HF diet and maintained on bedding than in HF-fed rats maintained on wire. Bacteria abundance associated with fibre fermentation was higher in LF-diet fed rats maintained on bedding compared with LF-fed rats housed on wire.
  
  
  CONCLUSIONS
  Maintaining rats in solid-based cages with corncob bedding alters large bowel fermentation and bacterial communities owing to ingestion of bedding. These changes may confound outcomes of nutritional studies, particularly those investigating the health effects of fibres. The use of wire-based caging may be justified in research of this type.
authors.affiliation: CSIRO, Food and Nutrition Flagship, Adelaide, South Australia, Australia.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Le Leu
authors.affiliation: CSIRO, Food and Nutrition Flagship, Adelaide, South Australia, Australia.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Conlon
authors.affiliation: CSIRO, Food and Nutrition Flagship, Adelaide, South Australia, Australia.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Bird
authors.affiliation: CSIRO, Food and Nutrition Flagship, Adelaide, South Australia, Australia.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Clarke
mesh_terms: D000818:Animals; D004063:Digestion; D005430:Floors and Floorcoverings; D006799:Housing, Animal; D007756:Laboratory Animal Science; D052756:Nutritional Sciences / Q000379:methods*; D051381:Rats
keywords: bedding; corncob; microbiota; rats; short-chain fatty acids; solid-based cages; wire-based cages