Fermentation pattern of tropical grass haylage and digestibility compared to hay in equine diet

Hay production is the most common form of forage conservation methods for horse feeding. However, haylage can be an alternative to hay. The present research assessed the nutritional value of Tifton-85 haylage by fermentation pattern, bromatological composition, and apparent digestibility compared to hay in the diet of Quarter Horse mares. Haylage was prepared with 700.0 g of dry matter (DM) kg-1 added with a biological inoculum and was assessed at 1, 3, 7, 14, 28, and 56 days of production. At 14 days, the protein content had decreased from 192.0 to 173.2 g kg-1 DM. The opposite was found for ammoniacal nitrogen, which rose from 0.61 to 1.14 g kg-1 DM of total nitrogen. No differences were found for the variables NDF, ADF, hemicellulose, pH, acetic acid, propionic acid and butyric acid, whose values were 734.3, 316.5 and 416.9 g kg-1 DM, pH 5.47 and 0.06, 0.003, 0.03 g kg-1 DM, respectively. Lactic acid contents were higher after 28 days of haylage production, reaching 2.39 g kg-1 DM at the last assessment. The contents of aflatoxins, fumonisin, and zearalenone in the plant were similar to those in the haylage at 0.95 µg kg-1, 0.60 mg kg-1, and 0.71 µg kg-1, respectively. The digestibility assay showed an increase in protein digestibility in the diet with haylage (675.1 g kg-1 DM) compared to hay (579.1 g kg-1 DM) of the same grass. Haylage can potentially be used to feed horses and its use is recommended starting at 28 days of production.