Evaluation of Rodent Diet Stability when Stored in Conditions that Diverge from Guide Parameters.

Abstract

An essential aspect of animal resource programs is the storage and provision of food for a variety of species. Environmentalparameters for feed storage conditions (temperature less than 70 °F; relative humidity less than 50%) are recommended in theGuide for the Care and Use of Laboratory Animals, along with aspects of nutrition such as palatability, vermin-control measures,diet quality, and integrity of feed bags. After receiving a suggestion for improvement for environmental conditions in2 feed storage locations during an AAALAC accreditation visit, we hypothesized that the packaging of contemporary rodentfeed could sustain wider environmental variations in temperature and humidity without adverse impact on integrityand palatability. This study evaluated representative feed storage sites across campus buildings to capture the variationin environmental conditions that are inherent to large and diverse animal care programs. Each test storage location held2 identical bags of feed (same type, lot, and expiration date) that were stored from June to September of 2021; some aspectsof the project were repeated during summer 2022 with a similar rodent feed. Baseline nutrients were analyzed from feedsamples collected at time 0 (control) and again after 1 and 3 mo of storage. The overall nutritional values measured in feed atthe end of the study were not significantly different from control values, regardless of test site and variation in environmentalparameters. Retinol (as a measure of Vitamin A) was the only component that decreased significantly; however, final retinollevels were consistently above those necessary for appropriate nutrition for mice. Our animal care program stakeholderswere briefed on the outcomes of this study with the intent to verify at future AAALAC site visits that our storage conditionsare adequate for maintaining the nutritional quality of packaged rodent feed.