Abstract
Soft-pelleted, high-fat diets (HFD) are greasy and crumble easily leading to food wastage and hair coat grease accumulation when mice are fed using commercially available feeders. The ideal HFD feeder design should reduce food wastage, facilitate mouse weight gain, and minimize variables such as hair coat grease accumulation that have the potential to alter scratching behaviors. Our study compared the feeding efficiency of 2 commercially available feeders (feeders A and E) to 4 novel feeder designs (feeders B, C, D, and F). Novel feeders had alterations in feeding aperture size, feeding surface area, feeder configuration, and level of food presentation. Male C57BL/6NCrl mice (n = 120; 4/cage) were randomly assigned to cages containing one of the 6 feeder types and were fed HFD for 12 wk. Feeders and cage bottoms were weighed before use and then weekly at the time of cage change. Mice were weighed before starting the HFD and then biweekly. Scratching behavior was video recorded at 0, 4, 8, and 12 wk. Hair coat grease accumulation was visually scored biweekly. Feeder A use was associated with the highest feed cost due to HFD wastage ($36.98 ± 1.54/cage/wk). Mice fed using Feeder A had the highest average weight gain (23.75 ± 0.8 g, P < 0.005). However, mice also had significantly higher hair coat grease accumulation scores (P < 0.05) and significantly increased scratching frequency at 4 wk (P < 0.05) when compared with mice fed using other feeder types. Novel feeder designs utilized 10 to 21 times less HFD dispensed when compared to feeder A. Mice fed using novel feeders also displayed improved welfare, as evidenced by low hair coat grease accumulation scores, and no significant differences in scratching frequency when compared with baseline behavior.