Effects of yeast inoculation and air exposure on the nutritive value of corn silages

摘要

Corn silages are prone to deterioration when exposed to air. The lactate-assimilating yeast species arc frequently the first microorganisms to initiate the aerobic deterioration. Some studies reported that acrobically unstable corn silage is associated with reduced nutritive value. Therefore, the objective of this study was to evaluate the influence of yeast inoculation (Pichia norvegensis) and the air exposure by 48 hours on the fermentative profile and digestibility of corn silages. Corn crop was harvested at 34% DM, treated without (Control) or with P. norvergensis at 1 x 105 cfu g"1 fresh matter (Yeast) and packed in large scale bag silos (401 silo"1). After 123 d of storage, silos were opened. Daily, silages were unloaded and fed to cows immediately (Fresh) or after 48 h of air exposure (Exposure). The four treatments were: control-fresh silage (CF), control-exposed silage (CE), yeast inoculated-fresh silage (YF), and yeast inoculated-cxposcd silage (YE), in a factorial design. The effects ofair exposure by 48 hours reduced lactic acid concentration (/5<0.001), increased the pH (.P=0.004) and also changed other acids, alcohols and esters concentrations. Moreover, there was a trend of decrease for the digestibilities of DM, NDF and TDN.