1.5kg. Psyllium Husks are the outer coating of Plantago ovata seeds and are high in indigestible fibre. Horses who graze on sparce, sandy pastures ingest sand into the digestive system where it can settle and potentially cause problems. When Psyllium Husks are wet they swell to form a gel which when passing through the digestive system aids sand clearance from the digestive tract by promoting gut motility.