Impact of live yeast and selenium supplementation on blood metabolites and rumen pH of young bulls after long-transport to the fattening unit

Long-distance transport and the receiving phase at the fattening unit are sources of stress for young beef cattle. This randomised controlled study involved 80 Charolais young bulls that underwent 12 h of transport from France to Italy and aimed at testing whether the animals have some benefits from the supplementation of live yeast and selenium through slow-release boluses and diet. The bulls were randomly allocated into two supplementation groups of 40 animals each, named Yeast and Control groups. Bulls of the Yeast group received a supplementation of Saccharomyces cerevisiae and selenium-enriched yeast (1.5 × 10¹⁰ CFU/bull per day of live yeast and 1.5 mg/bull per day of selenium) by two slow-release ruminal boluses 1 day before leaving France, and a live yeast supplemented diet once in Italy (8 × 10⁹ CFU/bull per day of live yeast). Yeast and control bulls underwent the same manipulations. Individual BW and complete blood metabolic profile were assessed at the arrival to the Italian fattening unit (day 0), after 7 days (day 7), and at the end of the receiving phase (day 30). The rumen environment was continuously monitored through reticulum-rumen sensors that measured several parameters in a subsample of 60 bulls, equally distributed between Yeast and Control groups. Saccharomyces cerevisiae and selenium supplementation did not affect growth performance and metabolic profile. However, the supplementation stabilised the rumen environment by limiting the daily pH amplitude and SD and the inter-animal variability. The Yeast group increased the time spent ruminating (+39 min/day) at day 30 compared to Control group. More stable ruminal conditions are important to support beef cattle health during the receiving period at the fattening unit, when animals face the delicate transition to high-energy diets.