The need to attempt to bale alfalfa hay at higher than optimum moisture level has increased in recent years due to unpredictable weather conditions driven by climate change. This often results in heating of the forage and a reduction in its nutritive quality. Although organic acids such as propionic acid (PA) are generally effective in preventing fungal growth in moist forage, the high rate of application and field handling costs coupled with environmental concerns makes hay producers reluctant to use them. The objective of this study was to assess the effects of applying Pediococcus pentosaceus (PED) and Pichia anomala (PIC) alone or in combinations with chitinase (CH) at baling on conservation characteristics of high moisture alfalfa hay. Alfalfa was harvested at the mid-bloom stage, wilted in the field to 73–77% DM (HMH) and baled without or with PED, PIC, PED+PIC, PED+CH, PIC+CH, and PA. Control (HMH), PED+CH, PIC+CH and PA and alfalfa hay baled at >85% DM (NMH) treatments were repeated over 3 yrs while other treatments were examined only within a single year. Interior temperature was recorded and samples were taken 90 d after baling for chemical and microbial assessment. Averaged over 3 yr, HMH had higher (P < 0.001) temperature degree days (>30°C, HDD) than NMH. The HDD of PED+CH was lower (P < 0.001) than that of other treatments in yr 1 and 3, but the max temperature achieved was lower (P < 0.05) for PED+CH as compared with other treatments only in yr 3. The NDF and NH₃-N contents were lower (P < 0.001) for PED+CH and PIC+CH, but WSC was higher (P < 0.001) for PED+CH than that of HMH and PA in yr 1. Mold and yeast counts did not differ among treatments, but CH⁺PED and CH⁺PIC had lower (P < 0.05) total culturable bacteria than other treatments in yr 1. The results indicated that P. pentosaceus and P. anomala combined with chitinase applied at baling have the potential to improve the conservation of HMH alfalfa by preventing spontaneously heating.