Experimental acute rumen acidosis in sheep: Consequences on clinical, rumen, and gastrointestinal permeability conditions and blood chemistry1

Abstract

Acute acidosis was induced in sheep, and gastrointestinal permeability was assessed by using lactulose as a permeability marker. Metabolism was evaluated by monitoring blood metabolites. Four rams (72.5 ± 4.6 kg BW) were used in a 2 × 2 changeover design experiment. The experimental period lasted 96 h from -24 to 72 h. After 24 h of fasting (from -24 to 0 h) for both controls and acidosis-induced rams (ACID), 0.5 kg of wheat flour was orally dosed at 0 and 12 h of the experimental period to ACID, while the basal diet (grass hay, ad libitum) was restored to control. At 24 h, a lactulose solution (30 g of lactulose in 200 mL of water) was orally administered. Blood samples were collected at -24, 0, 24, 48, and 72 h of the experimental periods for the analysis of metabolic profiles and during the 10 h after lactulose dosage to monitor lactulose changes in blood. In addition, rumen and fecal samples were collected at 24 h of the experimental period. The acidotic challenge markedly reduced (P < 0.01) rumen pH and VFA but increased rumen d- and l-lactic acid (P < 0.01). Concurrently, a decrease of fecal pH and VFA occurred in ACID (P < 0.01), together with an abrupt increase (P < 0.01) of lactate and fecal alkaline phosphatase. Blood lactulose was significantly increased in ACID peaking 2 h after lactulose dosage. Blood glucose, β-hydroxybutyrate, Ca, K, Mg, and alkaline phosphatase showed a significant reduction (P < 0.05) at 24 h, whereas urea and NEFA declined (P < 0.05) from 48 to 72 h. A strong inflammatory acute phase response with oxidative stress in ACID group was observed from 24 to 72 h; higher values of haptoglobin (P < 0.01) were measured from 24 to 72 h and of ceruloplasmin from 48 (P < 0.05) to 72 h (P < 0.01). Among the negative acute phase reactants, plasma albumin, cholesterol, paraoxonase, and Zn concentration also decreased (P < 0.05) in ACID at different time points between 24 and 72 h after acidotic challenge start. A rise (P < 0.05) of reactive oxygen metabolites and a drop of vitamin E (P< 0.01) between 24 and 72 h were indicative of oxidative stress in ACID. The perturbation of these blood metabolites suggests that acute acidosis was effectively induced by our model. The increase of lactulose in blood in ACID indicates that gastrointestinal permeability for the marker increased and the large increment after 2 h from dosage suggests that most of the passage occurred through the rumen or abomasal walls.

Abundance of ruminal bacteria, epithelial gene expression, and systemic biomarkers of metabolism and inflammation are altered during the peripartal period in dairy cows

“…However, damages of epithelium permeability (Minuti et al, 2013(Minuti et al, , 2014 make the interaction between LPS and other bacterial immunogens and resident immune cells (macrophage and dendritic cell) more probable, hence, increasing the risk of inflammatory events originating from the gastrointestinal tract (Minuti et al, 2013(Minuti et al, , 2014.…”

Ruminal acidosis: strategies for its control

“…Health disorders which result from acidogenic diets, in acute acidosis are based on the degree of pH ruminal decrease (Garret et al 1999, Kleen and Cannizzo 2012, Minuti et al 2014. The presence of large amounts of lactic acid in the ruminal fluid and its rapid entry into the blood system demand a great challenge from the buffering capacity of the ruminal intake and body fluids.…”

Innate immune responses to metabolic stress can be detected in rumen fluids

“…Moreover, some of the signs attributed to SARA are dysfunctions common also to other digestive and metabolic disorders. These may affect the complex perception of satiety (Sartin et al, 2011), cause the release and absorption of immune-stimulating molecules such as lipopolysaccharides or histamine (Eckel and Ametaj, 2016;Minuti et al, 2014;Minuti et al, 2015;Nocek, 1997) and determine the modification of the microbiota (Minuti et al, 2015;Weimer, 2015;Yáñez-Ruiz et al, 2015). Because of this complexity, we have investigated the possible role of other factors involved in the forestomach functions.…”

“…The pH of the rumen fluids was measured immediately after withdrawal by a pH meter (GLP 21; Crison Instruments SA, Alella, Barcelona, Spain). An aliquot of the remaining fluid was immediately cooled in ice water and centrifuged at 3,000 × g for 10 min at 10°C; 2-mL aliquots of the supernatant were transferred into tubes with 1 mL of 0.12 M oxalic acid and frozen at -20°C for later gas-chromatographic analysis of volatile fatty acids (VFA), according to methods described in Ahmed et al (Ahmed et al, 2013) and Minuti et al (Minuti et al, 2014). …”