Effects of wilting extent on the concentration of phytoestrogens, nutritional value, microbial populations, and in vitro ruminal methane emissions of red clover hay and silage across stages

ABSTRACT: We evaluated the effects of insufficient (WET) or extended (CUR) wilting on the concentration of phytoestrogens, nutritional value, microbial populations, in vitro ruminal methane emissions, and in situ degradability of red clover silage (DM: 294 and 453 g/kg) and hay (DM: 651 and 891 g/kg, respectively) across storage stages. Measurements were taken at the start of storage (STRT), after 14 d (early stage of storage), and once storage processes had stabilized for hay and silage (50 and 78 d, respectively; late stage). Only late samples of hay and silage were tested for the in situ procedure. Data were analyzed as a randomized complete block design (5 blocks) with a 2 (wilting extents) × 2 (conservation methods) × 3 (storage stages) factorial. Results showed that storage DM losses were greater for WET versus CUR hay, but no differences were observed within silage. The CUR hay and silage preserved better sugars during storage relative to WET. Due to microbial spoilage, the NH3-N of WET hay was greater than CUR hay after 14 d of storage, but the opposite was observed after 50 d. The NDF of WET hay increased across storage stages, whereas it remained stable for CUR hay. In contrast, the NDF levels of both WET and CUR silage decreased during the ensiling period. The WET hay favored the growth of molds during storage, whereas CUR hay reduced their counts after 50 d of storage. For silage, mold counts were lower in WET compared with CUR after 14 d of storage, but no differences were observed after 78 d. When the ensiling period is limited to 14 d, the aerobic exposure DM losses and heating were greater for CUR silage compared with WET. However, when the ensiling period was extended to 78 d, no differences were observed between WET and CUR silage in terms of aerobic exposure DM losses and heating degree days. The CUR hay preserved ruminal in vitro DM fermentation kinetics compared with WET, whereas the ruminal DM fermentation kinetics of silage were not affected by the wilting extent. For both conservation methods, WET reduced methane yield only at the end of storage. The in situ rumen degradability kinetics showed that ensiling decreased the potentially degradable DM and CP fractions compared with haymaking. Haymaking reduced the ruminal degradation rate of DM but not of CP, compared with ensiling. Wilting was more critical for silage than hay in decreasing the concentration of formononetin and biochanin A. Across storage stages, hay had lower formononetin and biochanin A than silage. Overall, wilting red clover further helps conserve the nutritional quality of hay and silage while reducing phytoestrogen levels.