PSXIV-10 Performance of ½ Angus-Nelore cattle in feedlot receiving diets with different fiber levels.

Abstract High-grain, low-fiber diets can cause acidosis, reduced intake, gastrointestinal tract epithelial damage and inflammation, impacting gain, efficiency, and morbidity. Therefore, different levels of forage neutral detergent fiber (fNDF) inclusion were evaluated for their effects on the performance of 60 intact 1⁄2 Angus- Nelore cattle with an initial average weight of 398±10 kg. During the first 50 days, two fNDF levels were tested, 12% or 7% fNDF (23.9% or 13.9% in total dry matter), using corn silage as forage fiber source. These diets contained 64% and 73.8% ground corn and 0.2% and 0.5% potassium chloride, respectively, for the 12% and 7% FDNf levels. Both treatments included soybean meal (1.5%), cottonseed (7%), urea (1.2%), mineral mix (2.1%) and monensin (25 ppm). Diets were formulated to meet protein and mineral requirements according to the RLM model (rlm.app.br). Weight gain and feed intake were measured in real- time with Intergado scales and Growsafe feeders respectively Weight gain was estimated by linear regression based on live weights (non-fasted) obtained from real-time scales at the water troughs. A completely randomized design was used, considering each animal as an experimental unit. All statistical analyses were performed using SAS UNIVERSITY (2012). At the end of the first 50 days of feedlot, the animals in the 12% and 7% fNDF groups reached average weights of 501.8 kg and 503.5 kg, respectively (P = 0.86). Dry matter intake also did not vary, being 11.4 kg/day for the 12% fNDF group and 11.6 kg/day for the 7% fNDF group (P = 0.24). Gain followed the same trend, with 2.14 kg/day for the 12% fNDF group and 2.30 kg/day for the 7% FDNf group (P = 0.20). Feed conversion was 5.56 for 12% fNDF and 5.23 for 7% fNDF (P = 0.13). Feed efficiency was 0.183 for 12% fNDF and 0.194 for 7% fNDF (P = 0.14). The results indicate that reducing the fNDF level from 12% to 7% did not significantly affect animal performance throughout the experimental period.