THE EFFECTS OF MOISTURE CONCENTRATION AND TYPE ON QUALITY CHARACTERISTICS OF ALFALFA HAY BALED UNDER 2 DENSITY REGIMES IN A MODEL SYSTEM

Alfalfa (Medicago sativa L.) hay was packaged in laboratory-scale bale s at nine moisture concentrations (250 to 358 g kg(-1)). Five concentr ations were obtained from the field during initial dehydration, and fo ur were obtained during the accumulation of dew at night. In the first study, bale density was increased as bale moisture increased (floatin g density; FD), thereby mimicking the confounded nature of these varia bles commonly observed with field-scale equipment. In the other study, this confounding was eliminated by maintaining a constant (400 kg/m(3 )) dry matter bale density (constant density; CD), regardless of moist ure content. Initial bale moisture was an excellent linear predictor o f storage characteristics and changes in quality and was consistent fo r both the CD and FD studies. Moisture type (residual hydration or dew ) had no effect on any response variable. Heating indices (degree days > 30 degrees C, degree days > ambient, mean heat generation rate, max imum temperature, and average temperature) were all effective in descr ibing changes in artifact nitrogen concentration as linear functions d uring storage (r(2) > 0.838). However, regression lines for FD and CD studies were dissimilar (different slope, intercept, or both) for all predictor variables except average temperature. The mechanisms that re gulate heat damage to forage nitrogen during bale storage are complex. Although input factors such as moisture content, spontaneous heating, and bale density clearly impact final artifact nitrogen concentration s, their interactions are not understood fully. (C) 1998 Elsevier Scie nce B.V.