ABSTRACT.- Livestock production in southern South America heavily relies on extensive native grasslands, characterized by high plant species diversity, which makes estimating forage digestibility and intake by ruminants in this pastoral ecosystem challenging. Therefore, the aim of this study was to generate regression models to establish the relationship between total faecal nitrogen excretion (FNe) and intake, and faecal nitrogen content (FNc) and digestibility in sheep fed multispecies native forage. In a completely randomized design, 16 Corriedale sheep averaging 44.4 kg of body weight (BW) were housed in metabolism cages and received forage in amounts of 15, 20, 25 g of dry matter per kg of BW or ad libitum. During the spring of 2019 and the summer of 2020, four measurement periods were carried out. The sheep had 5 days of adaptation to the metabolic cage, 10 days to adapt to the treatments of amounts of forage offered, and 5 days for intake and digestibility measurements. The forage was harvested once a day, and then the fresh forage was offered at two different times, 8 and 17 h. © 2024 Elsevier B.V.