Effect of replacing ground corn with cactus pear Nopalea cochenillifera (L.) on feed intake and digestibility, water intake, milk production and composition in Holstein × Gyr cows.

The objective of this study was to evaluate the intake and digestibility of nutrients, production and composition of milk, and water intake of lactating dairy cows fed standard diets in which ground corn (C) was replaced by up to 100% in the diet by cactus pear (CP). Eight Girolando cows (½ Gyr x ½ Holstein), 3rd calf multiparous, with 60 to 80 days of lactation and an average weight of 450.0 ± 30.0 kg, were randomly distributed in a double Latin square (4 × 4). Four experimental diets were evaluated: (100% C + 0% CP), (66.6% C + 33.3% CP), (33.3% C + 66.6% CP), and (0% C + 100% CP). There was a difference (P < 0.05) in the intake of CP and EE (kg.day^- 1), with a quadratic effect and a linear reduction, respectively, with substitution. The maximum CP intake of 3.05 kg.day^- 1 was found at 46.07% and EE intake fell by 3.81 g for each percentage unit of cactus pear added to the diet. There was a quadratic difference (P < 0.05) for DM intake in %BW and g.kg BW^0,75, with maximum values of 3.97%BW and 186.8 g.kg BW^0,75 with the substitution of 54.83 and 53.17%, respectively. There was a quadratic effect (P < 0.05) for the intake of NDF in %BW, with the maximum intake of 1.3% at the 74.69% substitution level. There was a linear reduction (P < 0.05) in the digestibility of DM, NDF, and TDN, and for the other nutrients there was no substitution effect (P > 0.05). There was no difference (P > 0.05) in milk production and composition. There was a linear reduction (P < 0.05) in water intake. Cactus pear can be used in a promising way to replace ground corn up to 100% in the diet of lactating dairy cows.