No-till drilling cereal rye (Secale cereal L.) and triticale (x Triticosecale Wittm. ex A. Camus.) into existing perennial pastures may increase the early spring forage inventory while maintaining beneficial ecosystem services inherent in no-till pasture systems. This interseeding system has not been well documented with cereal rye and triticale in majority tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) and orchardgrass (Dactylis glomerata L.) pastures. An equal mix of cereal rye and triticale was drilled into existing pastures in early fall of 2020 and 2021. Cereal rye and triticale were interseeded at 0, 67, and 135 kg ha–1 with either 0 or 45 kg nitrogen ha–1 at planting in a 2 × 3 factorial randomized complete block design with four replications. The forage was harvested the following spring at boot stage and analyzed for herbage accumulation and nutritive value. Herbage accumulation increased by 500 kg ha–1 after interseeding 135 kg ha–1 of rye and triticale. Adding 45 kg nitrogen ha–1 independently increased dry matter herbage accumulation by 474 kg ha–1. Although, interseeding rye and triticale moderately reduced nutritive value parameters compared to the pasture, the nutritive value in all treatments remained high (relative feed value  135 with 17% crude protein). Fall nitrogen fertilizer increased herbage accumulation but had no effect on nutritive value. This shows that interseeding rye and triticale into pastures can be an applicable strategy to boost spring herbage inventory in perennial cropping systems dominated by cool-season grasses while maintaining good nutritive value.