| LPS (Lipopolysaccharide), which is an important part of Gram-negative bacteria, will be released during the death and rapid growth process of Gram-negative bacteria and cause various diseases in ruminants such as respiratory tract infections and mastitis. In the dairy industry, it is a common practice to feed dairy cattle with a high concentrate diet in order to improve milk production. Intaking large amount of high grain feeding would lead to a rapid fermentation. The greater accumulation of VFA decreases the rumen pH and induces SARA(subacute ruminal acidosis) of the dairy cow. Dramatic changing of the rumen environment alter the rumen microbiota and result in the death of bacteria. The released LPS is absorbed into peripheral blood through some ways and result in further effects on the dairy cattle. In order to study the physiological affect and the ruminal changing of dairy cattle under SARA, we used three primiparous lactating Holstein cows (260 to 285 d in milk) in a 3×3 Latin square design to assess the effects of three doses (0.0,0.4, and 0.8 μg/kg of body weight) of lipopolysaccharide (LPS, Escherichia coli O111:B4) and collected the blood sample and ruminal sample. Finally study the changing at the level of physiological,rumen fermentation and rumen microbiota.1 Influence of lipopolysaccharide infusion on the levels of amino acid, protein and lipid in peripheral blood in dairy cattleThree primiparous lactating Holstein cows (500±25 kg) were used in a 3×3 Latin square design to assess the effects of three doses (0,0.4, and 0.8μg/kg of body weight) of LPS (Escherichia coli O111:B4) on the levels of levels of amino acid, protein and lipid in peripheral blood in dairy cattle in dairy cattle. The results showed that LPS infusion significantly increased (P<0.05) the concentrations of blood urea nitrogen and triglyceride, while decreased(P<0.05)the levels of globulin, albumin, glucose, total protein, cholesterin, taurine, threonine, serine, glycine, citrulline, a-amino butyric acid, isoleucine, lysine, proline and arginine, while no significant changes (P> 0.10) were observed for the levels of D-Aspartic acid, valine, ornithine, P-Alanine, P-serine, glutamic acid, α-aminoadipic acid, alanine, cysteine, methionine, cysthi, leucine, tyrosine, phenylalanine, hydroxylysine, y-aminoadipic acid,3-methyl histidine, monoethanolamine, cystathionine, β-aminoisobutyric acid,1-methylhistidine, histidine and carnosine between the control and the LPS treatment. Collectedly, these findings indicate that LPS administration influenced the concentrations of the amino acid, protein and lipid in peripheral blood in dairy cattle and could result in a lower milk quality. These findings also imply that the translocated LPS during high grain feeding is one of main inducers for the decrease in the quality of milk.2 Intravenous lipopolysaccharide challenge rumen metabolism in dairy cattleThree primiparous lactating Holstein cows (260 to 285 d in milk) were used in a 3×3 Latin square design to assess the effects of three doses (0.0,0.4, and 0.8 μg/kg of body weight) of lipopolysaccharide (LPS, Escherichia coli O111:B4) on changes in rumen fermentation. Ruminal pH was linearly decreased (P< 0.001) by LPS challenge, and the concentrations of acetate, propionate, butyrate, total volatile fatty acid and amino nitrogen increased linearly (P< 0.001) according to the LPS dose. LPS infusion linearly decreased (P< 0.001) the organic matter degradability of alfalfa hay and soybean meal in the rumen, but did not affect (P> 0.10) the gene expression of Na+/K+ ATPase and monocarboxylic acid transporter 1,2 and 4. Our data suggest that systemic LPS could alter rumen environment, leading to a general decrease in fermentative activity.3 Intravenous lipopolysaccharide challenge alters the ruminal bacterial microbiotaThree primiparous lactating Holstein cows (260 to 285 d in milk) were used in a 3×3 Latin square design to assess the effects of three doses (0.0,0.4, and 0.8 μg/kg of body weight) of lipopolysaccharide (LPS, Escherichia coli O111:B4) on changes in rumen microbiota. A plot of principal coordinates analysis based on unweighted UniFrac values and molecular variance analysis revealed that the structure of ruminal bacterial communities in the control was distinct from that of rumen microbiota in the cattle exposed to LPS.At the phyla level, when compared with the control group, LPS infusion in the tested cows linearly increased (P< 0.05) the abundance of Firmicutes, and linearly decreased (P< 0.05) the percentage of Bacteroidetes, Tenericutes, Spirochaetes, Chlorobi and Lentisphaerae. To our knowledge, this is the first study to report that intravenously LPS challenge altered the rumen bacterial microbiota and fermentation profiles. Our data suggest that systemic LPS could alter rumen environment and ruminal microbiota composition, leading to a general decrease in fermentative activity. |
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