Raman spectroscopy of fresh feces is a practical tool for identifying animal species and estimating diet characteristics

This study evaluated for the first-time a handheld Raman spectroscopy (RS) device to differentiate animal species and estimate diet characteristics by detecting biomolecules in fresh feces from large (bovine) and small (goat) ruminants, hindgut fermenter (equine), and non-ruminant (swine). The herbivores` diets were forage-based, with access to pasture and ad libitum coastal bermudagrass hay. The pigs received a commercial pelleted grower ration with 160 g/kg of crude protein. Of the 46 fecal samples collected, 21 were from bovine (cattle; 16 cows and 5 calves), 5 from equines (horses, all mares), 8 from goats, and 12 from swine (pigs). Distinct concentrations of undigested biomolecules such as carotenoids, cellulose, and lignin in the feces of each species could be identified by RS. The RS indicated that cattle, goat, and horse diets consisted of 24%, 53%, and 14% fresh grass and 76%, 47%, and 86% hay, respectively. Calves and adult cattle could be distinguished by their feces using the RS. Cellulose, nonstructural carbohydrates, proteins, and fat digestion by ruminants, equines and pigs substantiated RS utilization for nutrition physiology studies in species with different digestive systems. Therefore, RS is a practical tool for identifying animals with different digestive systems and understanding diet specificities. •For the first time, Raman spectroscopy was used in fresh feces.•Species with distinct digestive systems could be identified.•Diet composition was estimated, and digestibility of certain molecules indicated.•Young and mature cattle could be identified.