Bioconversion of alperujo into an alternative feed for ruminants by pretreatment with live yeasts and/or exogenous fibrolytic enzymes

Extraction of olive oil through a two-stage centrifugation process produces a large amount of phytotoxic waste known as alperujo. This research was performed to bioconvert alperujo into enriched ruminant feed by pretreatment with exogenous fibrolytic enzymes (EFE) or/and live yeasts (LY). These additives were used in a completely randomized design with 3 EFE doses (0, 4, and 8 µl/g dry matter) and 3 LY doses (0, 4, and 8 mg/g dry matter) in a 3 × 3 factorial arrangement. Fermented alperujo with both EFE doses converted some of their hemicellulose and cellulose to simple sugars and increased bacterial abundance in the rumen. As a result, it shortens the lag time of rumen fermentation, increases the rate and amount of rumen fermentation, and improves digestibility. This improvement provides additional energy that can be used by ruminants to produce milk and by rumen microbiota to produce short-chain fatty acids. Fermented alperujo with a high dose of LY decreased their antinutritional compounds and reduced their high content of lipid. In the rumen, this waste became rapidly fermentable, and rumen bacteria became more abundance. Fermented alperujo with a high dose of LY + EFE accelerated rumen fermentation and improved rumen digestibility, energy available for milk production, and short-chain fatty acids compared to the use of LY or EFE alone. This synergistic interaction between these two additives increased protozoa abundance in rumen and the ability of rumen microbiota to bioconvert ammonia–nitrogen to microbial protein. Ultimately, fermentation alperujo with EFE + LY is a good strategy with minimum investment for a social sustainable economy and environment.