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Background: In ruminants, physiological and nutritional changes occur peripartum. Weinvestigated if gastro-intestinal microbiota, rumen metabolism and antioxidant status were affectedaround parturition and what could be the impact of a daily supplementation of a live yeast additivein late gestating ewes. Methods: Rumen, feces and blood samples were collected from 2 groupsof14 ewesone month and a few days before parturition, and 2 weeks postpartum. Results: In thecontrol ewes close to parturition, slight changes in the ruminal microbiota were observed, witha decrease in the concentrationF. succinogenesand in the relative abundance of the Fibrobacteresphylum. Moreover, a decrease in the alpha-diversity of the bacterial community and a reducedrelative abundance of the Fibrobacteres phylum were observed in their feces. Control ewes wereprone to oxidative stress, as shown by an increase in malondialdehyde (MDA) concentration, alower total antioxidant status, and higher glutathione peroxidase (GPx) activity in the blood. Inthe yeast supplemented ewes, most of the microbial changes observed in the control group werealleviated. An increase in GPx activity, and a significant decrease in MDA concentration weremeasured. Conclusions: The live yeast used in this study could stabilize gastro-intestinal microbiotaand reduce oxidative stress close to parturition. [ABSTRACT FROM AUTHOR]

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Summary: The gastrointestinal tract (GIT) of healthy cattle is the main reservoir of enterohaemorrhagic Escherichia coli (EHEC). Therefore, it is crucial to better understand the physiology of EHEC in the bovine GIT. In this study, we demonstrate that aspartate present in bovine small intestine content (BSIC), was exhausted after incubation of the reference EHEC strain EDL933 but was poorly assimilated by the endogenous microbiota. Furthermore, the bovine commensal E. coli strain BG1 appeared less efficient than EDL933 in aspartate assimilation suggesting a competitive ability of EHEC to assimilate this amino acid. Our results strongly suggest that aspartate, internalized via the DcuA aspartate: succinate antiporting system, is then converted to fumarate and carbamoyl‐aspartate, the precursor for UMP biosynthesis. Aspartate assimilation by these two pathways conferred a competitive growth advantage to EHEC in BSIC. In summary, supply of intracellular fumarate due to aspartate deamination and used as an electron acceptor for anaerobic fumarate respiration, as well as de novo synthesis of pyrimidine from aspartate appear to be important pathways favouring EHEC persistence in the bovine gut. Aspartate probably represents an ecological niche for EHEC in the bovine small intestine. [ABSTRACT FROM AUTHOR]

High morbidity and mortality rates of calves dramatically impact the sustainability of the dairy industry. Probiotics are investigated for their potential to alleviate health challenges. The objective of the study was to determine the effect of live yeast Saccharomyces cerevisiae var. boulardii CNCM I-1079 (SB) supplementation in pre-weaning calves. Thirty Holstein calves were enrolled at d6 of age and were offered daily 8 L of milk replacer with ad-libitum access to water and pelleted starter. Calves were balanced in term of parity of the dam and birth weight and randomly assigned to two experimental groups, designated as supplemented and Control. Supplemented calves received 2x109 cfu/d of SB added in the milk replacer. Every abnormal health condition, such as gut and respiratory disorders, as well as therapeutic treatments were recorded daily for each animal. A linear mixed model was performed to assess the impact of the supplementation on the different variables measured. Two fecal samples were collected at d10 and d60 of the trial to analyze bacteria diversity and taxonomic composition by amplicon sequencing. The overall health was improved in SB calves with fewer diarrhea cases detected compared with Controls (0.7 vs 2.2/calf, respectively, P = 0.001) and fewer SB calves experiencing respiratory disease (6.3 vs 50% respectively, P = 0.090). Along with those observations, a lower number of SB calves received a therapeutic treatment (18.8 vs 62.5% respectively, P = 0.029). Consequently, SB calves weighed 3 kg more compared with the Controls at the end of the experiment (P = 0.087). SB calves significantly presented a greater relative abundance of Akkermansia, a genus involved in immune system maturation, and a greater proportion of Lactobacillales and Negativicutes (lactate users) indicating likely better adaptation of their fecal microbiota to the milk diet than in Controls. [ABSTRACT FROM AUTHOR]

Dietary, environmental, and social stresses induced by weaning transition in pig production are associated with alterations of gut microbiota, diarrhea, and enteric infections. With the boom of -omic technologies, numerous studies have investigated the dynamics of fecal bacterial communities of piglets throughout weaning but much less research has been focused on the composition and functional properties of microbial communities inhabiting other gastrointestinal segments. The objective of the present study was to bring additional information about the piglet bacterial and archaeal microbiota throughout the entire digestive tract, both at the structural level by using quantitative PCR and high-throughput sequencing, and on functionality by measurement of short-chain fatty acids and predictions using Tax4Fun tool. Our results highlighted strong structural and functional differences between microbial communities inhabiting the fore and the lower gut as well as a quantitatively important archaeal community in the hindgut. The presence of opportunistic pathogens was also noticed throughout the entire digestive tract and could trigger infection emergence. Understanding the role of the intestinal piglet microbiota at weaning could provide further information about the etiology of post-weaning infections and lead to the development of effective preventive solutions.