Twenty one crossbred yearlings Holstein-Zebu heifers, with average initial age and weights of 14 months and 245 kg, respectively, were used in the performance evaluation. For evaluation of the ruminal parameters and sampling of the consumed pasture, five Limousin x Nelore steers, fistulated in the rumen and esophagus and maintained in an extra pasture of Brachiaria brizantha cv. Marandu, were used to evaluate ruminal parameters, pasture intake and to collect pasture samples. The experiment was carried out during three experimental periods, according to a complete randomized design. The following supplements, daily fed at 10 a.m., were used: mineral salt (SALT), supplements based on corn and corn gluten meal (CMCG) and corn and soybean meal (CSBM), supplied at the level of 0.5 kg/animal. There was supplementation effect on the performance of the yearlings heifers. The animals fed CSBM and CMCG were similar and superior than the animals fed SALT, and the average daily gain were, respectively, 0.920, 0.883, and 0.708 kg/animal. There were effects of supplementation, collection time and interaction between supplement and time on ruminal pH, and supplementation and interaction between supplement and time on ruminal ammonia. The ruminal ammonia concentrations of the steers submitted to the treatment with ruminal degradable protein (CSBM) were 23 and 30% superior, in the average, than the control (SALT) and ruminal undegradable protein (CMCG) treatments, respectively. The pH values and ruminal ammonia concentration, although influenced by supplementation and altered in function of times of collect, kept at adequate levels for ruminal fiber digestion and fermentation.
supplements; pastures; pH; ammonia
