Analysis of fecal microbiome and metabolome changes in goats with pregnant toxemia

Pregnancy toxemia is a common disease, which occurs in older ewes that are pregnant with multiple lambs in the third trimester. Most of the sick goats die within a few days, which can seriously impact the economic benefits of goat breeding enterprises. The disease is believed to be caused by malnutrition, stress and other factors, that lead to the disorder of lipid metabolism, resulting in increased ketone content, ketosis, ketonuria and neurological symptoms. However, the changes in gut microbes and their metabolism in this disease are still unclear. The objective of this experiment was to evaluate the effect of toxemia of pregnancy on the fecal microbiome and metabolomics of ewes. Eight pregnant ewes suspected of having toxemia of pregnancy (PT group) and eight healthy ewes during the same pregnancy (NC group) were selected. Clinical symptoms and pathological changes at necropsy were observed, and liver tissue samples were collected for pathological sections. Jugular venous blood was collected before morning feeding to detect biochemical indexes, and fecal samples were collected simultaneously using 16SrRNA and Liquid Chromatography-Mass Spectrometry (LC-MS) techniques to detect different flora and metabolites. Autopsy revealed that the liver of the pregnancy toxemia goat was enlarged and earthy yellow, and the biochemical results showed that the serum levels of aspartate aminotransferase (AST) and β-hydroxybutyric acid (B-HB) in the PT group were significantly increased, while calcium (Ca) levels were significantly reduced. Sections showed extensive vacuoles in liver tissue sections. The microbiome analysis found that the richness and diversity of the PT microbiota were significantly reduced. Metabolomic analysis showed that 125 differential metabolites were screened in positive ion mode and enriched in 12 metabolic pathways. In negative ion mode, 100 differential metabolites were screened and enriched in 7 metabolic pathways. Evidence has shown that the occurrence of pregnancy toxemia is related to gut microbiota, and further studies are needed to investigate its pathogenesis and provide research basis for future preventive measures of this disease.