Abstract
Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen. Early separation of newborns from the dam and distribution of artificial milk (Artificial Milking System or AMS) could impair rumen microbial colonization, which would not only affect rumen function but also have possible negative effects on hindgut homeostasis, and impact animal health and performance. In this study, we monitored microbial communities in the rumen and the feces of 16 lambs separated from their dams from 12 h of age and artificially fed with milk replacer and starter feed from d8, in absence or presence of a combination of the live yeast Saccharomyces cerevisiae CNCM I-1077 and selected yeast metabolites. Microbial groups and targeted bacterial species were quantified by qPCR and microbial diversity and composition were assessed by 16S rDNA amplicon sequencing in samples collected from birth to 2 months of age. The fibrolytic potential of the rumen microbiota was analyzed with a DNA microarray targeting genes coding for 8 glycoside hydrolase (GH) families. In Control lambs, poor establishment of fibrolytic communities was observed. Microbial composition shifted as the lambs aged. The live yeast supplement induced significant changes in relative abundances of a few bacterial OTUs across time in the rumen samples, among which some involved in crucial rumen function, and favored establishment of Trichostomatia and Neocallimastigaceae eukaryotic families. The supplemented lambs also harbored greater abundances in Fibrobacter succinogenes after weaning. Microarray data indicated that key cellulase and hemicellulase encoding-genes were present from early age in the rumen and that in the Supplemented lambs, a greater proportion of hemicellulase genes was present. Moreover, a higher proportion of GH genes from ciliate protozoa and fungi was found in the rumen of those animals. This yeast combination improved microbial colonization in the maturing rumen, with a potentially more specialized ecosystem towards efficient fiber degradation, which suggests a possible positive impact on lamb gut development and digestive efficiency.
Highlights
Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen
In current commercial dairy systems, early maternal separation of the newborn combined with distribution of milk replacer (MR), which could be defined as Artificial Milking System (AMS) are put in place in order to maximize farmer revenue from raw milk
Previous research conducted in our team showed that the distribution of a live yeast additive very early in age could accelerate microbial establishment of functional communities in the rumen of lambs reared with their dams[16] and stimulate the set-up of fibrolytic bacteria in gnotobiotically-reared lambs maintained into sterile isolators[17]
Summary
Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen. A higher proportion of GH genes from ciliate protozoa and fungi was found in the rumen of those animals This yeast combination improved microbial colonization in the maturing rumen, with a potentially more specialized ecosystem towards efficient fiber degradation, which suggests a possible positive impact on lamb gut development and digestive efficiency. The less vigorous or smaller ones are directed to AMS These rearing practices induce animal stress and increase the risk that young ruminants suffer from digestive problems during the pre-weaning phase, which may affect growth performance, and deteriorate gut health with pathogen emergence. These troubles might be linked to perturbations of the maturation of the digestive tract, correlated with poor rumen/intestine colonization by functional beneficial microbial communities after birth. We measured the development of microbial diversity, abundance, composition of Bacteria, Archaea and Eukaryotes, and of the fibrolytic potential of the microbiota in the rumen as a proxy of rumen function and digestive capacity and in the feces as a proxy of gut health
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