A Do-it-yourself System for Scheduled Feeding of Laboratory Rodents in Their Home Cage

Summary

This paper details the design, assembly, and protocol for an automated feeding system along with an alternative lid and cage modification that can be implemented on standard rodent cages with minimal modifications for tethered optogenetic or fiber photometry experiments. The feeding system offers a cost-effective tool for timed feeding and/or caloric restriction.

Abstract

Intermittent fasting and research surrounding the influence of timed caloric restriction on body weight regulation and aging outcomes are trending, both in society and in the laboratory. To study time-restricted feeding and/or caloric restriction in the laboratory, allotted quantities of food are dispersed at scheduled time intervals. Current technology for scheduled feeding of rodents involves either specialized cages with gated food entry ports, time-locked digital hoppers, or manual food delivery. Specialized equipment for such experiments can be costly and manual feeding often requires investigators to come in for late night/early morning time points, precluding prolonged studies. The automated feeding system described here provides a cost-effective tool for timed feeding and/or caloric restriction that can be implemented on standard rodent cages with minimal modifications. The protocol uses an off-the-shelf autofeeder that is outfitted to a standard microisolator cage lid (mouse, hamster, rat, or guinea pig cage lids) and can administer the desired food allotments at programmed time intervals in the animal's home cage. Our design can be modified to accept various feeders or slight variations in cage dimensions. We provide the design, assembly, and protocol for the feeding system along with an alternative lid and cage modification for tethered optogenetic or fiber photometry experiments.

Introduction

Intermittent fasting is an important area of metabolic and aging research. Proper alignment of feeding and circadian rhythm can alter the effect of diet on body weight^1,2,3,4. Further, prolonged intermittent fasting is associated with increased longevity and improved age-related disorders^5,6,7,8. Research studies implementing long-term fasting protocols (>20 days) typically require specialized equipment. While ....

Protocol

All procedures were approved by the University of Massachusetts Amherst Institutional Animal Care and Use Committee.

1. Assembly of autofeeder onto a standard microisolator cage lid (Figure 1)

1. Using a rotary tool with a 1.5" cutting wheel, cut out a 20 x 25 mm square into a microisolator cage lid. Position the opening 2.75 cm from the edge of the lid and centered above the wire rack (Figure 1B, left).
2. 3D print a bracket to couple the autofeeder onto the cage lid (Figure 1A and Supplemental....

Results

A caloric restriction study (21 days) to induce infertility in female mice (autofeeder and cage design, Figure 4A)
Chronic energy deficiency is sufficient to inhibit fertility in mammals, a response that is conserved in rodents and humans alike^11,12. In this study, we use caloric restriction to induce long-term bodyweight loss. Adult female C57BL/6 mice, 15-18 weeks old were single-housed and on a 12:12 h light:d.......

Discussion

In preclinical animal models, caloric restriction is a powerful experimental tool to precisely manipulate and study metabolism. Sustained weight loss has implications in obesity, diabetes, aging, fertility, and menopause (a type of reproductive aging), all of which are important translational endpoints. Caloric restriction paradigms, however, can be difficult to sustain for an extended time. In this manuscript, we offer a cost-effective solution to achieve long-term caloric restriction in a laboratory setting. Provided a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
#7 Stopper W/ 3-1/2" curved sipper tube no ball	Labex	2067
AN75 mouse cage bottom	Ancare	AN75HT
Automatic Fish Feeder for Aquarium	Petbank-tek.com	Amazon distribution (#B0BRCWP16K)
Rodent Micro-filter Tops	Ancare	N10MBTPLF
Rubber Stoppers, One Hole	United Scientific	S24009
standard rodent chow	Prolab IsoPro 3000