Abstract
The aim of this study was to investigate the effect of a probiotic, Saccharomyces cerevisiae I-1077 (Levucell ® SC), on microbial colonization of the rumen of newborn lambs. Results from two experiments, both including 12 lambs, half of lambs receiving daily 0.2 g of Levucell ® SC, are reported. The yeast tended to stimulate growth of cellulolytic bacteria. These species were present earlier and their numbers were higher in SC lambs than in controls. Establishment of protozoa also took place earlier in the rumen of lambs receiving SC daily. During the first week after birth and when lambs began to ingest solid feed, the physico-chemical and fermentative parameters were altered in the rumen of lambs, which had received yeast, suggesting more efficient fermentation processes. These effects were partly due to the oxygen-scavenging capacity of SC, which was characterized by lower redox potential in the rumen of SC lambs. These results represent good arguments to suggest that this probiotic may be able to accelerate the functionality, or improve the stability of the rumen ecosystem in young ruminants.