Forage preservation method influences alfalfa nutritive value and feeding characteristics

Forage preserved as baled silage can reduce dry matter and quality losses compared with hay systems if sufficient stretch wrap is layered to adequately exclude oxygen. The objectives of this study were to determine the optimum film amount for alfalfa (Medicago sativa L.) preserved as round bale silage and to compare the forage quality and losses to that of dry hay. Two field trials compared alfalfa silages wrapped in two, four, or six layers of plastic film and hay controls. Bales wrapped with four or six layers had significantly lower temperatures than two layer treatments. In Trial 1 (July harvest), silage with two layers had higher post-storage neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) concentrations than did silage prepared with either four or six layers. No consistent differences in forage quality parameters were observed among silage treatments in Trial 2 (September harvest). After 5 mo, concentrations of ADF, NDF, and ADL in the silages with four or six layers of film were lower than hay in both trials; however, crude protein (CP) did not differ across preservation treatments. In a preference trial, cows (Bos taurus) offered all treatments from Trial 2 preferred silages preserved with four or six layers of film to the two-layer treatment and hay control. We conclude that more than two layers of film are needed for consistent preservation of alfalfa round bale silage. The results demonstrated the potential advantage in quality for alfalfa baled silage compared with conventionally harvested and stored hay.