Consumo, parâmetros ruminais e concentração de uréia plasmática em novilhos alimentados com diferentes níveis de torta de girassol em substituição ao farelo de algodão

The objective of this study was to assess the effects of five substitution levels of cotton meal by sunflower cake in the concentrate ration, on dry matter intake (DMI), pH and ammonia nitrogen (N-NH3) in the rumen liquid and plasmatic urea in beef steers. The diets were isoprotein (13.0% CP) and isoenergetic (72.0% TDN). In natura sugarcane silage was the only ronghage (40% DM). Five 1/2 Simental x Nelore, castrated males were used, with average weight of 380 kg and 24 months old, all fistulated in the rumen. The treatments were: 0% sunflower cake (TG0); 25% sunflower cake (TG25); 50% sunflower cake (TG50); 75% sunflower cake (TG75); and 100% sunflower cake (TG100), based on DM, substituting cotton meal (FA). The experiment was carried out in a 5x5 Latin square experimental design, with five animals and five periods. Each experimental period lasted 15 days. The dry matter intake (DMI) presented significant difference (P < 0.05), showing that substituting cotton meal by sunflower cake resulted in lower DM intake, but this substitution did not (P > 0.05) alter the pH and N-NH3 values of the rumen liquid and plasmatic urea values. It was concluded that sunflower cake can be used in substitution to the cotton meal when mean daily gains are expected, since in high levels of substitution it caused a decrease in DMI.