Different Ground Corn Particle Size in Supplements for Young Bulls Grazing During Intensive System Production

Abstract We hypothesized that a decrease in flint corn particle size in the supplements of young bulls during grazing promotes better use of starch in the total gastrointestinal tract, with less starch lost in the feces, thus increasing growth performance. This experiment aimed to evaluate the effects of supplements with different ground corn particle sizes on the growth performance, economic analysis, intake and apparent digestibility of nutrients for beef cattle in Urochloa brizantha cv. Marandu pastures during the rainy-dry transition season. Sixty-four Nelore bulls, with an average age of 16 months and 303.6 ± 18.0 kg of body weight (BW), were distributed in a completely randomized design. The treatments were WG = whole grain (geometric mean particle size, dgw, 6.262 µm); CG = coarse ground grain (dgw, 2.882 µm); MG = medium ground grain (dgw, 1.011 µm); and FG = fine ground grain (dgw, 0.621 µm). The supplements with ground grain or whole grain were similar (P > 0.05) in terms of intake and the digestibility of dry matter (DM), forage, organic matter (OM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), and total digestible nutrients (TDN). However, the starch digestion in the total tract was higher (P  0.05) the starch digestion in the total tract. The starch fecal concentration decreased with ground grain compared with that for whole grain (P  0.05). Supplementation with CG promoted a slightly greater net revenue (+ 11.51%) and return per ha (+ 12.8%) compared with WG, while MG and FG yielded worse economic results. Therefore, CG showed higher economic performance and efficiency utilization of starch, suggesting it is a better strategy for providing supplements to young grazing bulls.