Results indicate that steaming represents a viable management strategy for reducing dustiness in hay containing elevated dust levels.
New management strategies for feeding horses with respiratory disease include steaming hay prior to feeding to reduce dustiness; however, little is known about the effectiveness of this practice.
The objective of this study, conducted at the University of Minnesota, was to determine the effect of steaming on dust concentrations in hay. Dust levels of two alfalfa-orchardgrass hays (low mold [LM] and moderately moldy [MM]) were measured pre- and post-steaming using a commercial hay steamer (The Professional Hay Steamer; Happy Horse Products, Ltd., Palmyra, VA). Prior to steaming for 90 minutes, one flake (1.70 ± 0.23 kg, DM) was removed from the center of each bale (control or non-steamed flake), and the remaining hay was re-tied. Dust content of the control flake was measured while the bale was steamed. After steaming, one flake of steamed hay (1.56 ± 0.34 kg, DM), was removed from the center of the bale, and dust content was measured. To measure dust, each flake was placed inside the drum of an electric cement mixer with two lead weights (3.0 kg) to encourage agitation of the hay. The cement mixer operated at 20 rpm, and total suspended particulate (TSP) levels were measured at the mouth of the drum using a tapered element oscillating microbalance sampler (1400a; Thermo Fisher Scientific, Waltham MA). Instantaneous TSP concentrations were recorded every 60 sec for 30 min. Measurements were averaged over 30 minutes; and the average expressed on a weight (kg) basis.
Initial dust content measurements were different between the two hays; 758 and 406 µg/m3 per kg DM for MM and LM, respectively. Steaming reduced the dust content of the MM hay to 345 µg/m3 per kg DM; however, dust content in the LM hay was not significantly affected by steaming (257 µg/m3 per kg DM).
Limited data is available regarding typical, or acceptable, concentrations of dust in feedstuffs commonly fed to horses. However, steaming of the MM hay reduced dustiness to levels comparable to the LM hay, which was considered an acceptable hay for horses. Additional research needs to determine acceptable levels of dust; until then, results from this study indicate that steaming represents a viable management strategy for reducing dustiness in hay containing elevated dust levels.
Authors: JE Earing, CC Sheaffer, BP Hetchler, LD Jacobson, JC Paulson, MR Hathaway and KL Martinson