Storage of large round bales of hay harvested at different moisture concentrations and treated with sodium diacetate and/or covered with plastic

Abstract

The effects were examined of applying sodium diacetate (1.25 g kg −1 of hay), an individual plastic cover, or both sodium diacetate and a plastic cover on temperatures, storage characteristics and digestibility, after outdoor storage, of large round bales of alfalfa-grass hay baled at either a high (190 g water kg −1 hay) or low (156 g kg −1) moisture concentration. High-moisture bales had higher ( P < 0.05) mean temperatures up to 50 days postharvest than low-moisture bales. Applying sodium diacetate or plastic covers did not affect the mean temperature of the whole bales, but plastic increased ( P < 0.05) the temperature in the interior of the high-moisture bales. High-moisture bales had a higher ( P < 0.05) crude protein (CP) concentration than low-moisture bales at harvest. High-moisture bales had higher ( P < 0.05) mean concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and acid detergent insoluble nitrogen (ADIN) than low-moisture bales after 17 and 39 weeks of outside storage. As a result, the mean concentration and recovery of digestible dry matter in vitro (IVDDM) were lower ( P < 0.05) for the high-moisture bales than for the low-moisture bales after storage. Plastic covers reduced ( P < 0.05) the proportion of hay which was weathered and the NDF concentration of both the weathered outside layer and the unweathered core of the bales after storage. As a result, plastic-covered bales had a higher ( P < 0.05) recovery of IVDDM and tended to have a higher recovery of unweathered dry matter. Sodium diacetate-treated bales had lower ( P < 0.05) concentrations of ADL and ADIN after storage. This was due to preservation of the bale core as sodium diacetate did not influence the proportion of the bale which was weathered nor the composition of the weathered layer. Also, sodium diacetate, did not significantly influence the recovery of total, digestible or unweathered dry matter. The digestibility of dry matter, CP, NDF, and ADF of bales stored outside for 24 weeks, determined in wether lambs, was not affected by hay moisture at harvest, plastic covers, or sodium diacetate treatment.