Small - grain cereals are promoted as forage alternatives that may substitute for other traditional crops when short cycle forages are required for cattle feeding. The objective of the work was to assess in vitro the nutritive quality, ruminal fermentation kinetics and digestibility by the gas production technique of forage from common oat ( Avena sativa cv. Canadiense) = AC, black oat ( Avena strigosa cv. Saia) = AN, Triticale ( ×Triticosecale Wittm . cv. Criollo) = T, and rye ( Secale cereale of national production) = C . The forage crops were sown in 250 m 2 plots, harvested and sampled 72 days after sowing in a completely randomised design with five replicates. Both oat species (AC and AN) had significantly higher crude protein and neutral detergent fibre contents (P<0.05) compared to T and C. In vitro gas production showed a higher fermentation rate for black oat and common oat, with no differences for in vitro digestibility (P>0.05) for the evaluated forages. There were also no differences in the estimated ME content (P>0.05). Results indicate that black and common oats are forages with a better nutritive quality when harvested at a similar time compared to triticale and rye forage.