The objective of this trial was to evaluate the effect of the partial replacement of corn by forage cactus (Nopalea cochenillifera Salm Dyck) in the diets of lactating goats on the nutrient intake, milk production and composition and ingestive behavior. Five crossbreed Saanen x Pardo Alpina goats with body weights of 47 ± 3.3 kg were used in the study. The design was 5x5 Latin square design, in which the treatments were as follows: 20, 25, 30, 35 and 40% of girl cactus included in the diet as a partial replacement of corn, with 0, 18, 36, 54 and 72% of the added the cactus comprising of gliricidia (Gliricidia sepium (Jacq) Walp) as roughage in all treatments. Treatment did not affect (P > 0.05) the dry matter intake, crude protein, neutral detergent fiber, acid detergent fiber and total digestible nutrients with the increasing levels of cactus in the diet, presenting means of 1.64, 0.26, 0.82, 0.54 and 1.17 kg day-1, respectively. In the same way, no influence was observed on the daily milk production and levels of fat, protein, lactose and total solids of milk, which averaged 1.18 kg day-1; 3.74, 3.34, 5.06 and 13.56%, respectively. The inclusion of cactus also had no influence (P > 0.05) on the ingestion behavior. The treatment with 35% cactus showed a lower impairment of food intake (31%). The partial replacement of the corn by the girl cactus in the diets of dairy goats can be accomplished because it does not alter the intake, milk yield and composition and feeding behavior. The replacement of up to 54% corn by the cactus is recommended to reduce producer costs for food.