235 Effects of Curing Extent on the Phytoestrogen Concentrations of Red Clover Hay and Silage Across Storage Phases

Abstract Our objective was to assess the effects of insufficient (WET) or ample (CUR) curing on the phytoestrogen concentrations of red clover silage (29.4 and 45.3% DM) and hay (65.1 and 89.1, respectively). Measurements were taken at the start of storage (STRT), after 14 d (MicA), and once storage processes had stabilized for hay and silage (50 and 78 d, respectively; LATE). Hay was packed into mini-bales (~500 fresh g; ~232 kg DM/m3) and silage into mini-silos (19.5 L; ~214 kg DM/m3). Data were analyzed as a randomized complete block design (5 blocks) with a 2 (curing extents) x 2 (storage methods) x 3 (storage phases) factorial. Differences were declared at P ≤ 0.05. The concentration of formononetin was greater in silage vs. hay at STRT (4,624 vs. 2,893 ± 175 mg/kg of DM, respectively), MicA (5,383 vs. 2,110), and LATE (5,666 vs. 2,569). Also, more formononetin was found in WET vs. CUR silage (5,841 vs. 4,608.1± 154 mg/kg of DM, respectively). However, no differences were observed between WET vs. CUR hay (x̅ = 2,524). At STRT, biochanin A was greater in silage vs. hay (3,105 vs. 2,012 ± 139 mg/kg of DM, respectively). A similar trend was observed at MicA (3,233 vs. 1,057), and LATE (3,295 vs. 1,228). In addition, more biochanin A was observed in WET vs. CUR silage (3,793 vs. 2,628.9 ± 127 mg/kg of DM, respectively). The opposite was observed in WET vs. CUR hay (1,219.5 vs. 1,644.9). The genistein concentration was greater in silage vs. hay at STRT (149 vs. 120 ± 8.36 mg/kg of DM, respectively), MicA (246 vs. 62.6), and LATE (264 vs. 72.9). Also, the concentration of genistein was greater in WET vs. CUR silage (236 vs. 202.3 ± 7.21 mg/kg of DM, respectively) but the opposite was observed in WET vs. CUR hay (72.8 vs. 97.3). In the case of daidzein, hay had a greater concentration of this phytoestrogen than silage (12.8 vs. 6.67 ± 0.43 mg/kg of DM, respectively). In conclusion, red clover silage maintains greater concentrations of formononetin, biochanin A, and genistein than hay during curing period and across the storage phase. Also, adequate curing is more beneficial for silage than hay in terms of decreasing the phytoestrogen concentrations.