A study was conducted to determine chemical composition and ruminal nutrient degradability of eight spineless cactus cultivars grown in northeastern Brazil. Results showed that neutral detergent fiber was similar for all cultivars and averaged 249 g · kg⁻¹ ± 7.3 SEM. Acid detergent fiber ranged between 148 g · kg⁻¹ and 207 g · kg⁻¹ with some significant differences between cultivars. Starch and water-soluble carbohydrates were similar for all cultivars and averaged 198 g · kg⁻¹ ± 6.3 SEM and 155 g · kg⁻¹ ± 9.0 SEM, respectively. Protein content was less than 50 g · kg⁻¹ with some significant differences between cultivars. Calcium was the mineral with the highest concentration followed by potassium and magnesium with no differences between cultivars. Effective ruminal degradability of dry matter and neutral detergent fiber were unaffected by cultivar and averaged 701 g · kg⁻¹ ± 8.4 SEM and 503 g · kg⁻¹ ± 5.8 SEM, respectively. It was concluded that cultivars had little impact on chemical composition and ruminal degradability of spineless cactus. Based on chemical composition and in situ ruminal degradability, spineless cactus can be considered an excellent source of fermentable carbohydrates for grazing and nongrazing ruminants. Because of its high carbohydrate quality, spineless cactus can be used an emergency feed or as part of a complete diet providing that the diet contains an adequate amount of degradable protein.