Desert heat degrades quality of stored alfalfa hay

To quantify the effects of summertime heat on baled alfalfa hay, we baled alfalfa in May 1993 in three areas of the irrigated Sonoran Desert and stored it for 20 weeks. At each site we subjected the bales to four different storage treatments: an air-conditioned room, unprotected in full sunlight, in full sunlight but covered with a plastic tarp, and under a roof. Temperatures of the bales stored in full sunlight, whether tarped or unprotected, often exceeded 120°F for extended periods of time. After 20 weeks, feed quality of the bales stored in full sunlight decreased more than the quality of the shaded bales and those kept in an air-conditioned room. Bales stored unprotected in full sunlight dried out excessively and became brittle. Protected from the scant summer rainfall, the tarp-covered bales did not bleach and were able to maintain moisture for a longer period of time. Among the three outdoor treatments, nutritive quality of alfalfa hay bales was best preserved by storage under a protective roof.