216 Autolysed yeast supplementation in finishing beef steers diets during feedlot
Abstract The objective of this study was to evaluate the productive performance, the ingestive behavior, the apparent digestibility of the feed, and the carcass characteristics of finishing beef steers during feedlot under different inclusions of autolyzed yeast (AY). For this, 36 ½ Angus steers (average BW 330 kg and 11 months of age), were distributed in a completely randomized way, consisting of three treatments and six replications (of two animals each): T1 - Control; T2 – AY 4g (diet with 4 g/animal/day of AY Saccharomyces cerevisiae product RumenYeast®), and T3 – AY 7g (diet with 7 g/animal/day of RumenYeast®), for 105 days, being 14 days of adaptation, two periods of 28 days and 1 of 35 days. The performance was evaluated, as well as the apparent digestibility of the diet, at the end of the 1st and 3rd periods with the total collection of feces. The carcass gain in the period was also calculated, and the thickness of fat on the Longissimus dorsi muscle was measured, as well as on the front, side, and back, using a digital caliper. The data were submitted to analysis of variance and the means compared to 5% of significance. The supplementation of AY 4g promoted higher daily BWG and better FCR during the adaptation feedlot period (P < 0.05), and the AY 7g did not differ from the other treatments. The animals that received AY ended up with higher fat thickness in the carcass than the control group (P < 0.05). The apparent digestibility of diets containing AY was higher than the control diet (P < 0.05). Based on these results, the supplementation of AY 4g yielded positive results in the initial phase of the feedlot, improved the apparent digestibility of DM, and resulted in better carcass finishing.