BACKGROUND: Accurately measuring activity and feeding is important in laboratory animal research, whether for welfare-monitoring or experimental recording. Quantification commonly involves manual pellet-weighing; however, this can physically disturb animals and cannot continuously assess both the amount and pattern of feeding over time. Improved means of food-intake measurement have been developed but can be costly and incompatible with many cage configurations.
METHODS: We developed thea novel home-cage monitoring system which continuously records food-intake, food-seeking activity, and ambient light conditions in laboratory mice. After benchtop validations, we tested this device by recording from C57BL/6J control mice under 12:12h light:dark (LD) and constant darkness (DD) to measure circadian rhythms in feeding behaviour. We then recorded from mice having disturbed circadian rhythms (cryptochrome 1 and 2 double-knockouts,), where irregular activity and feeding patterns were expected. Animals were individually housed within Digital Ventilated Cages(DVC, Tecniplast) to measure home cage activity. After habituation, 48-hourand DVC recordings were collected and compared. SnackerTracker-Cry1,Cry2 -/--/-SnackerTrackers SnackerTracker ®
RESULTS: Theaccurately measured food-masses throughout benchtop andvalidation tests. Time-coursefeeding traces correlated well with DVC activity recordings, indicating that feeding reflects general cage locomotion in control and cryptochrome-deficient animals. In LD,data showed expected feeding/fasting cycles in control and cryptochrome-deficient animals yet reduced dark-phase feeding in cryptochrome-deficient mice. In DD, increased feeding during the subjective nighttime was maintained in control animals but abolished in cryptochrome-deficient mice. Surprisingly, cryptochrome-deficient animals exhibited ultradian feeding rhythms. SnackerTracker in vivo SnackerTracker SnackerTracker
CONCLUSIONS: We validate the performance and value of monitoring home cage feeding using the. Here we show that cryptochrome-deficient animals have decreased food-intake in LD, diurnal arrhythmicity in DD, and ultradian rhythms in feeding behaviour. Theprovides a cost-effective, open-source, and user-friendly method of animal food intake and activity measurement. SnackerTracker SnackerTracker
