Alternative Forages as Roughage for Ruminant: Nutritional Characteristics and Digestibility of Six Exotic Plants in Azores Archipelago

SIMPLE SUMMARY: The potential use of exotic plants in animal feed provides a source of fiber for grazing ruminants when there is a shortage of pasture. The objective of this research was to evaluate the nutritional value, digestibility, and gas production potential of six exotic plants present in the Azores. Samples of these plants were collected and their chemical composition and potential as forage food were evaluated. Data analysis included univariate and multivariate methods. The results obtained showed variations among the studied forages in terms of crude protein, and fibers: NDF, ADF, and ADL. The gross, metabolizable, and digestible energy of E. globulus and C. japonica showed higher values than the other plants. P. undulatum with a relative food value of 92.12% stood out from the other plants. In gas production, the values of gas produced by A. donax stand out, as the species that presented the highest gas production, observing a significant difference) for the other plants. P. undulatum stands out for presenting good quality in the RFV index and A. donax for having good digestibility, both can be used as forage in periods of greater scarcity of pastures. ABSTRACT: This study aimed to evaluate the nutritional potential of unconventional plants: Pittosporum undulatum, Cryptomeria japonica, Acacia melanoxylon, Hedychium gardnerianum, Eucalyptus globulus, and Arundo donax, as an alternative roughage for ruminants. Chemical composition, gross energy, in vitro gas production, kinetics, and digestibility of dry matter and organic matter in vitro were determined for each species. The obtained results showed variations between the studied forages concerning crude protein, and the different fiber fractions: NDF, ADF, and ADL The P. undulatum with a relative food value of 92.12%, showed a significant difference compared to the other species under study. After 96 h of incubation, the plants that produced, on average, less in vitro gas were A. melanoxylon and E. globulus. Among the studied species, A. donax stands out as the species that presented the highest gas production, with 31.53 mL. 200 mg(−1) DM, observing a significant difference compared to the other plants. This is a reflection of it having the highest DMD (60.44 ± 1.22%) as well. P. undulatum was the species with the longest colonization time (4.8 h). Among the plants studied, we highlight P. undulatum as presenting a good quality in the RFV index and A. donax as having good digestibility. Both can be used as roughage in periods of greater shortage of pastures.