YIELD, QUALITY AND PRESERVATION OF MOIST HAY SUBJECTED TO RAIN-FREE AND WEATHERED CONDITIONS

Abstract

The effects of moisture level and a neutralized propionate preservative on yield, quality and preservation of rain-free and weathered alfalfa (Medicago sativa L.) hay were studied in separate trials. Moisture levels of 252, 185 and 138 g kg−1 in rain-free hay and 297, 211 and 180 g kg−1 in weathered hay were designated as High, Medium and Low, respectively. The weathered hay received 66 mm of rain at about 600 g kg−1 moisture and another 15 mm prior to baling at the Low moisture level. The preservative (680 g kg−1 propionic acid equivalent) was applied at 1.25 and 1.50% (wt wt−1) for rain-free and weathered hay, respectively. The High and Medium moisture level treatments had similar harvested dry matter (DM) yields in both rain-free and weathered hay. Rain-free hay DM yield at harvest was 6–9% higher for the High and Medium treatments than the Low moisture level, while for the weathered hay the Medium level was 3.0% higher (P < 0.05) than the Low moisture level. Poststorage forage qualities of the Low and Medium moisture level treatments were similar and higher than the High moisture treatment (P < 0.05) in rain-free hays, while the Medium level treatment was highest (P < 0.05) for forage quality in weathered hay. The Medium moisture level compared with Low moisture level resulted in 10.4, 10.6 and 15.8% higher yields of DM, in vitro digestible organic matter (IVDOM) and crude protein, respectively, in rain-free hay and 3.1, 6.3 and 5.7% higher, respectively, in weathered hay. The propionate was inconsistent in preventing DM loss during storage, but reduced temperature and mould count in both hay types. Application of 1.25 and 1.50% (wt wt−1) of propionate improved poststorage IVDOM by 2.0 and 3.6%; increased crude protein yield by 3.0 and 5.7% and IVDOM yield by 3.3 and 5.7%; reduced neutral detergent fiber by 5.4 and 7.6%; reduced acid detergent fiber by 5.4 and 7.1%; and reduced acid detergent insoluble nitrogen by 9 and 18% in rain-free and weathered hay, respectively. It is recommended that large round bales be harvested at moisture levels somewhat above 170 g kg−1 for both rain-free and weathered hay with or without a neutralized propionic acid preservative. Serious losses may occur above 250 g kg−1 moisture with or without the use of a preservative. Key words: Alfalfa, moist hay, neutralized propionate, large round bales, weathering, preservation