SummaryThe main objective of this study was to determine the impact of rumen cannulation on the microbial community of goat rumens using 16S rRNA high-throughput sequencing. Twelve Boer crossbred goats were used in the experiment: six goats were surgically fitted with rumen cannula, and the other six were used as controls. All goats were fed the same diet for 20 days, after which their rumen digesta were sampled once per week for three consecutive weeks. Total microbial DNA was extracted from the collected rumen fluid and was used as a template to amplify the V4 hypervariable region of the 16S rRNA gene. High-throughput sequencing was performed using an Illumina MiSeq platform, and the sequences were analyzed primarily using the Quantitative Insights into Microbial Ecology pipeline software. The results showed that the Chao 1 index, the observed species index and the Shannon-Wiener index were not significantly different (p > 0.05) between the two groups. Bacteroidetes, Firmicutes, Tenericutes were the predominant phylum in both groups, and their relative abundance was 60.63%, 29.48%, 2.24% (n = 6, CT group) and 61.17%, 26.92%, 1.66% (n = 6, RC group) respectively. At the phylum level, the relative abundance of Proteobacteria was significantly higher (p < 0.001) in the microbial communities of RC goats, and Planctomycetes and Chloroflexi were significantly lower (p = 0.02). The abundances of other phyla were not significantly different between treatments. A total of 19 lower-level taxa also exhibited significant differences (p < 0.05) in relative abundance between the groups. In addition, there were 18 genera shared within the control group, 26 shared within the rumen-cannulated group, and 16 shared by both groups. Prevotella was the most abundant shared genus, although its abundance was not significantly different (p > 0.05) between the groups. In conclusion, although the most abundant microbes kept stable, rumen cannulation had the potential to significantly change rumen microbial communities in goats.

This study was designed to evaluate the effect of heat stress on endotoxin flux across mesenteric-drained and portal-drained viscera of dairy goats. Three Saanen first lactation dairy goats were surgically fitted with indwelling catheters in the portal vein, the mesenteric vein and carotid, and were kept in thermal-neutral and then heat stress environment, for examining the effect of heat stress on endotoxin absorption and redox status. Average net absorption of endotoxin (EU/h) across mesenteric-drained viscera (MDV) and portal-drained viscera (PDV) during the whole period of heat stress increased by 279.05% and 227.92% in relation to thermo-neutral period. Plasma concentration of glutathione peroxidase (GSH-Px) and catalase (CAT) in mesenteric and portal vein, and that of superoxide dismutase (SOD) in mesenteric vein, increased significantly during heat stress. Main conclusions were: (i) net absorption of endotoxin in portal vein is mainly from non-mesenteric tissues both in heat stress and in thermo-neutral condition; (ii) heat stress may lead to the significant decrease in plasma SOD, GSH-Px, CAT flux across PDV and MDV, and the significant increase in endotoxin flux across PDV and MDV; and (iii) the increase in gastrointestinal permeability in dairy goats during heat stress may not be induced by the increase in oxidative stress.

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