350 Effects of Adding Yeast Derivatives to High Concentrate Diets on Performance and Feeding Behavior of Beef Cattle Finished in Feedlot

Abstract

Abstract Yeast derivatives enhance beef cattle performance (Torres et al., 2022), allowing farmers to increase feedlot financial income. However, yeast derivatives vary on yeast species, grown medium, purity, technological processing, yeast cell parts marketed.Thus, in these experiments, we aimed to understand the potential of different yeast derivatives to manipulate performance, feed intake, and feeding behavior. In experiment 1, 1,760 non-castrated males were used to study performance and feed intake. These animals were distributed in large pens, mimicking actual feedlot operations. In xperiment 2, 96 animals with radio frequency identification ear tags were allocated in small groups with induvial access to automatic feeders equipped with scales to study daily individual feeding behavior. Animals were allocated to four treatments: 1) Control, no yeast derivative; 2) AY - 7g/animal/day, autolyzed Saccharomyces cerevisiae grown on sugarcane molasses, RumenYeast (ICC, São Paulo, Brazil); 3) YM - 3g/animal day, yeast rich in soluble yeast metabolites; 4) YB - 5g/animal/day, yeast blend (live Yeast plus autolyzed Yeast. Orthogonal contrasts were performed comparing control against AY, YM, and YB. Differences were declared significant at P < 0.05 and as a trend when 0.05 < P < 0.10. Pen was considered as the experimental unit for experiment 1. For experiment 2, animals were considered the experimental unit. Regarding experiment 1, AY tended to increase adjusted average daily gain and hot carcass weight (Table 1). Dry matter intake did not differ between treatments in experiment 1 (large pen trial). Looking at individual intake data, experiment 2, feeding behavior and water intake changed when yeast derivatives were included in the diet. In general, animals supplemented with AY spent less time eating, which was more evident in the adaptation period (Table 1). AY and YB had stimulated feed intake in some periods of experiment 2. However, the evident less time spent eating by the AY group promoted a greater feeding rate (kg ingested/min) markedly compared with YM and YB, but in general, also greater than control. Considering the initial period of feedlot operations, this greater feeding rate could favor animals supplemented with AY to adapt faster to feedlot diet/feeding conditions. All yeast derivatives increased water intake. In summary, autolyzed Saccharomyces cerevisiae grown on sugarcane molasses increased beef cattle performance and feeding rate. This change in feeding behavior may accelerate the adaptation of beef cattle in the transition from the backgrounding phase to the feedlot operation.