LAUSR

This study, conducted at São Paulo University feedlot, Dracena, Brazil, was designed to evaluate the effect of adding either high-moisture corn, calcium salts of fatty acids (CSFA), or organic Zn+Cr on feedlot performance and carcass traits of Nellore cattle fed for 112 days. One-hundred fifty 18-mo-old Nellore bulls (404±24kg) were used and initially ranked, according to sires’ information, into groups of high and low EPD. Secondly, cattle were blocked by weight and randomly allocated to 30 pens (n = 5/pen), which were randomly assigned to the following 2x2 + 1 arrangement of treatments: Finely-ground corn, High-moisture corn, Finely-ground + CSFA, High-moisture corn + CSFA, and High-moisture corn + CSFA + Zn (90 ppm) and Cr (0.45 ppm). All diets contained 25 ppm of monensin. On day 0, one animal per pen was randomly selected to be slaughtered for baseline purposes. The replacement of finely-ground by high-moisture corn increased (P < 0.05) final BW (585 vs. 573 kg), ADG, HCW (321 kg vs. 315 kg) and decreased (P < 0.01) DMI (9.7 vs. 10.1 kg). Likewise, the addition of CSFA increased final BW, ADG (1.62 vs. 1.50 kg), and HCW (321 vs. 314 kg). The addition of Cr+Zn led to increased (P = 0.02) dressing percentage. No treatment effect was observed on final marbling (P > 0.55). It was observed interactions between treatments and EPD for G:F (P = 0.02) and final 12thrib-fat thickness (P = 0.03), where cattle from low-EPD groups needed high-moisture corn, CSFA and organic Zn+Cr to improve G:F and increase fat deposition; however, animals from high-EPD groups required only high-moisture corn. The adding of either high-moisture corn, CSFA, or organic Zn+Cr improved feedlot performance of Nellore cattle, and its effects seemed to be more effective in animals from low-EPD groups.