The aim of this study was to evaluate the effect of the level of hay and concentrate on total hay intake and supplied already, the additive/substitutive effect and total apparent digestibility of the diet intake in diets for goats. Experiment I: diets: Alfalfa hay (A1), Alfalfa hay + corn (0.5% LW/day) (A2), + 1% LW/day (A3), + 1.5% LW/day (A4). Experiment II: diets: Natural grassland hay (CN) (R1), hay CN + corn (0.5% LW/day) (R2), hay CN + corn (1% of LW/day) (R3), + 1.5% of LW/day) (R4). Intake, ratio forage/concentrate and total apparent digestibility were calculated. Experiment I: There were no effects (p> 0.05) on the CMST for the corn tested levels and recorded a linear decrease (p <0.05) in the CTFDN, CTFDA and CTPB. The CMSF decreased linearly (p <0.05) with increasing amounts of corn by verifying a hay effect on the concentrate. The F/C was different (p <0.05) in all treatments. The DTAIVMS increases linearly (p <0.05) with the content of corn in the diet. Experiment II: a linear increase (p <0.05) on the CMST and CTPB with increasing corn in diet and no differences (p> 0.05) on the CMSF, CTFDN and CTFDA is observed. The F/C and CTPB differ (p <0.05) among all the diets tested. The DTAIVMS increases linearly (p <0.05) with the content of corn in the diet. Therefore, it can be concluded that the increase of maize levels improved the total digestibility of the ration consumed and the substitute or additive effect depended on the quality of the hay used.Facultad de Ciencias Veterinaria
