Nutrient digestibility in horses of tropical grasses found in semi-arid areas of the Brazilian Northeast region assessed using mobile bags

ABSTRACT The present study used mobile bags to estimate horse nutrient digestibility of tropical grasses found in semi-arid areas of the Brazilian Northeast region. Five female mixed-breed horses with a mean weight of 400±23 kg were assigned to a 5×5 Latin square design with five periods of seven days and five grasses: Tifton 85 hay ( Cynodon spp. ), sixweeks threeawn ( Aristida adscensionis Linn.), Alexandergrass ( Brachiaria plantaginea (Link) Hitchc), capim-de-raiz ( Chloris orthonoton Doell), and Sabi grass ( Urochloa mosambicensis ). The nutrient content of forages was determined prior to inoculation in horses and after recovery of mobile bags from feces. The digestibility coefficients were determined from the difference between the inoculated and recovered material. The dry matter, organic matter, mineral matter, crude protein, neutral detergent fiber, and acid detergent fiber contents of the grass species were analyzed. Digestibility data were subjected to analysis of variance using the Statistical Analysis System (SAS, version 9.0) software. Higher dry matter digestibility coefficients were observed in Tifton 85 (74.61%), Alexandergrass (74.30%), and capim-de-raiz (68.88%) than in sixweeks threeawn (48.40%) and Sabi grass (52.89%). The highest crude protein digestibility coefficients were found for Alexandergrass (95.70%), Tifton 85 (93.50%), and sixweeks threeawn (93.35%). Sixweeks threeawn had lower apparent mineral matter digestibility than the other grasses. The digestibility coefficients of Alexandergrass and capim-de-raiz indicate that those grasses have potential to be used in equine feed.