The effects of a nutritional packet (live yeast, vitamins C and B1, and electrolytes) offered during the final phase of feedlot steers on growth performance, nutrient digestion, feeding behavior, and methane emissions
Tonelli Nardi, Kaue
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The effects of a nutritional packet offered to beef steers during the final 64 d of the feedlot finishing phase on growth performance, carcass characteristics, total tract apparent nutrient digestibility, and feeding behavior were evaluated. Crossbred-Angus steers (n = 120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment) in a randomized complete block design where pen represented the experimental unit. A steam-flaked corn-based finishing diet was offered ad libitum, and the treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet. Ground corn was used as a carrier for the nutritional packet and included at 1 % of diet DM. The nutritional packet was formulated to provide 1.7 × 1010 CFU/steer-daily of Saccharomyces cerevisiae, 162 mg/steer-daily of Vitamin C; 400 mg/steer-daily of Vitamin B1; 2.4 g/steer-daily of NaCl, and 2.4 g/steer-daily of KCl. Data were analyzed using the GLIMMIX procedure of SAS. Average daily gain of BW (P = 0.89), DMI (P = 0.57), and gain efficiency (P = 0.82) were not affected by the inclusion of the nutritional packet. The 12th rib fat deposition increased (P = 0.02) by 17.5% for cattle offered the nutritional packet, followed by a also greater (P = 0.03) calculated yield grade. The NDF and ADF digestible intake (kg/day) were 7.53 and 11.9% greater (P ≤ 0.02) for treated cattle, respectively. Steers offered the nutritional packet had increased (P ≤ 0.02) digestibility of DM, OM, NDF, and ADF, while a tendency (P = 0.08) was observed for hemicellulose. Steers feeding behavior treatment × period interactions (P ≤ 0.03) were observed for eating time (min/d) and eating rates (min/kg of consumed DM, OM, fiber, and digestible DM, OM, and fiber), in which steers offered the nutritional packet did not differ between periods, while steers offered the control treatment decreased such behavior activities on d 63. Rumination, drinking, active, chewing, and resting times were not affected (P ≥ 0.28) by treatments. The nutritional packet improved nutrient digestibility with no effect on nutrient intake which may have led an increased carcass-fat deposition. Such effect associated with no deleterious effects on growth performance, and a more stable eating behavior during the final 64 days on feed can potentially warrant less days on feed when cattle receive such nutritional packet.