The aim of the present study was to evaluate the effect of substituting Tifton-85 grass hay with different quantities of xiquexique (Pilosocereus gounellei) (0, 12, 24, and 36%) on the nutrient intake and physiological responses of lactating dairy cows. Eight multiparous crossbred cows at approximately 100 days in milk, with an average milk yield of 15 kg of milk per day(-1), and an average body weight (BW) of 465.20 +/- 39.37 kg, were distributed in a 4 x 4 double Latin square design. Each experimental period lasted 16 days, consisting of 10 days for adaptation and 6 days for data collection, giving a total of 64 experimental days. The roughage: concentrate ratio was 60: 40, on a dry matter (DM) basis. The DM intake, expressed in kg day(-1), was affected quadratically by the levels of xiquexique in the diets. The intakes of DM, expressed in % BW and g kg-(0.75), and neutral detergent fiber (NDF) in the three units analyzed (kg day(-1), % BW, and g kg(-0.75)), as well as the intakes of organic matter (OM), crude protein (CP), ether extract (EE), and total carbohydrates (TC), expressed in kg/day(-1), decreased linearly with the levels of xiquexique in the diet. Milk yield (kg day(-1)) was reduced by the addition of xiquexique into the diet, but feed efficiency was not influenced. Water intake from feed (WIFeed), expressed in kg day(-1) and % BW, incresed linearly with increasing levels of xiquexique in the total diet, while voluntary water intake, expressed in kg day-1 and % BW (WIVoluntary), decreased linearly. The total water intake (WITotal) was not affected by experimental treatments. Participation of WIVoluntary in the WITotal linearly reduced with Xiquexique levels in the diet. The respiratory rate and surface temperature during both periods of the day (morning and afternoon), and rectal temperature during the morning were not influenced by the levels of xiquexique in the diet. Therefore, xiquexique can be utilized in the feeding of medium and high producing dairy cows, as a means of reducing nutrient intake, milk yield, and voluntary consumption of water without changing feed efficiency or the animals' physiological responses.
