The nutrient content of available native fodders for sheep under tropical conditions is low, while the nutrient requirements of sheep, particularly during late pregnancy, are high. This study aimed to enhance the nutritive value of various indigenous fodders using formulated feed block supplementation to address nutrient insufficiency in late-pregnant crossbred Batur sheep. Five basal diets were formulated from native fodders with and without feed blocks supplementation (FS). Treatments were arranged in a 5 × 2 factorial design, with the first factors being five basal diets and the second factors being supplementation with and without feed block. Each treatment had six replicates. The results showed significant interactions effect (p < 0.01) between the basal diets and supplementation on in vitro digestibility, ruminal pH value, NH3-N, total volatile fatty acids (VFA) concentration, ...