Pur-A-Plus is a vitamin enriched viable yeast culture (Saccharomyces cerevisiae) supplement for horses. Yeast improves the micro- ora in the hind gut by increasing the number of cellulytic and lactic-acid-utilizing bacteria, and this enhances bre digestion. Pur-A-Plus is ideal for older horses, horses prone to colic, horses under stress (shipping and training), horses receiving antibiotics and horses with hay bellies.