CorGest M (Mannanase) CorGest M (Mannanase) CorGest M contains Mannanase. Mannan is one of the components of hemicellulose in plant cell walls.β-Mannanase hydrolyzes β-D-1,4 mannopyranoside linkages of β-1,4-mannan into simple molecules such as manno-oligosaccharides and mannose. Mannanase helps to facilitate more nutrients in feeds in order to improve growth performance.