Diet-induced obesity in C57BL/6J
C57BL/6J male mice 5-6 weeks of age are transferred from The Jackson Laboratory—West production room to the In Vivo research laboratory. The mice are ear notched for identification and housed in individually and positively ventilated polycarbonate cages with HEPA filtered air at a density of 4 mice per cage. Filtered tap water, acidified to a pH of 2.8 to 3.2, and LabDiet 5LL4 are provided ad libitum. After a 7 day acclimation period, the mice are switched to a ~60% kcal fat (this is a common point of customization). We recommend allowing animals to reach 45 g before proceeding on a weight loss or anti-diabetic protocol, although lower weights may still be efficacious heavier mice will provide the greatest potential for change.
The Jackson Laboratory also has mice available that have been maintain on a 60% Kcal Fat Diet over a broad range of time periods should time restraints require already obese mice. In these circumstances a stabilization period of 3 weeks is recommended after importation into our Sacramento, CA facility.
Normative body weights are expressed in the graph below. Variation in weight gain on the 60% kcal diet supports a sample size of 7-8 mice in order to detect a 12% change in weight with 90% confidence
