Long-Term Storage of a Natural-Ingredient Diet within Variable Conditions of Temperature and Humidity

Institutions with aging structures may face difficulties maintaining consistent temperature and humidity for feed storage due to continued daily use of older heating, ventilation, and air conditioning systems and maintenance of structural integrity since the environmental efficiency of buildings often reduces as structures age. Consequently, institutions can face difficult financial decisions regarding whether repairs or new structures should be considered when compliance with standards is inconsistent. Replacing running or currently functioning heating, ventilation, and air conditioning systems that lack efficiency in comparison with newer systems is often not considered wise use of institutional resources. As this concern was faced and discussed during a recent campus AAALAC site visit to our institution, our IACUC requested additional information related to safe storage of feed in our current older buildings. Three test group environments of control/Guide for the Care and Use of Laboratory Animals (Guide)-recommended temperature/humidity, variable temperature/humidity, and high temperature/Guide-recommended humidity were used to store feed for a total of 6 mo. Full feed analysis, retinol levels, thiamine levels, and mold/yeast levels were evaluated at 0, 3, and 6 mo following storage. Study findings demonstrated that the nutritional content for feed remained relatively equivalent across the timespan as well as across the different storage conditions. More importantly, all storage conditions showed no increases in yeast/mold growth and acceptable levels of both thiamine and retinol at 6 mo. Our findings suggest that the diet tested was still usable for feeding animals after storage in the tested conditions that fall outside of Guide parameters and that other institutions may consider feed stability evaluation when addressing challenges with maintaining Guide parameters in feed storage spaces.