Calcium oxide reduces fermentation losses and improves the nutritional value of brewery-spent grain silage

Brewery spent grain (BSG) is an available beer coproduct used in animal feeding. However, high moisture and high fermentative substrate negatively affect the conservation parameters of BSG silages. The present study aimed to evaluate the effect of increasing calcium oxide (CaO) levels on BSG silage fermentation profile, losses, chemical composition, in vitro degradation, and aerobic stability. Ninety-six experimental silos were used in a randomized blocked design to evaluate the following treatments: I) BSG without additives; II) BSG with 10 g/kg dry matter (DM) of CaO; III) BSG with 20 g/kg DM of CaO; and IV) BSG with 30.0 g/kg DM of CaO. CaO linearly increased ( P ≤ 0.011) the silage pH and ethanol and acetic acid concentrations. In addition, treatments quadratically affected ( P ≤ 0.027) ammonia-N, butyric, and branched-chain fatty acids concentrations. CaO application in BSG silage linearly decreased ( P = 0.001) the silage effluent losses and total losses (DM basis). However, treatments showed a quadratic effect ( P ≤ 0.012) on gas losses and DM recovery. Intermediary levels of CaO increased gas losses and decreased DM recovery. CaO quadratically affected ( P ≤ 0.025) silage DM and organic matter content, and degradation of DM and neutral detergent fiber (NDF). On the other hand, CaO linearly decreased ( P < 0.001) silage NDF and acid detergent fiber content. Thus, CaO increases BSG silage pH and DM recovery and improves silage nutritional value. • It was evaluated the effect of calcium oxide treatment on brewery spent grain silage. • Calcium oxide decreased losses and improved dry matter recovery of silage. • Alkali treatment of BSG reduced fiber content and increased dry matter degradation. • Calcium oxide treatment improved nutritional value of BSG silage.