changes in gene expression of metabolically active proteins in ruminal epithelium of lambs fed with oil and monensin

background: high grain diets in ruminants increases the risk of digestives disorders such as acidosis which may lead to high economic loss. objectives: this experiment was conducted to determine the effects of an unsaturated and polyunsaturated fatty acid and monensin on gene expression of enzymes involved metabolic pathway of cell proliferation and rumen epithelial intracellular ph regulation. methods: twenty two male afshari lambs with live body weight of 45 ± 8 kg and six month age were used in a completely randomized design with 3 treatments replicates for 77days including 21 days adaptation period. experimental diets were consisted of a basal high concentrate diet (16% cp and 2.75 mcal/kg me) and 1) no additive (control, c= 8 lambs), 2) 30 mg monensin/day/head during the whole experimental period (t1= 8 lambs), and 3) (polyunsaturated fatty acidduring the whole experimental period (t2 = 6 lambs). lambs were killed after 77 days on the treatment diets. results: compared with the c treatment, relative abundance of mrna of monocarboxylate transporter isoforms mct1, mct4 and the ketogenic enzyme 3-hydroxy-3 methyl-glutaryl coa-synthase (hmgcs2) were higher for the t1 treatment. the expression of cholesterolgenic enzyme hmgcs1 was down-regulated for the t1 treatment and that of hmgcs1 was up- regulated for the t2 treatment. the expression of mct1 and mct4 were down-regulated for the t2 treatment. monensin had an additional impact on the mrna abundance of epithelial scfa- and acid-base transporters with concurrent changes in rumen epithelial thickness. conclusions: the results suggest that adding monensin and oil as nutritional means to reduce acidosis cause changes in mrna expression of vfa transferring proteins and limiting enzyme in the synthesis of cholesterol and ketone bodies in the rumen epithelium.