The present study investigated the effects of a feed additive and rumen microbial modifier, monensin sodium (monensin), on selected variables in lactating dairy cows. Monensin fed cows (MON, 600 mg d(-1)) were compared with untreated control cows (CON, 0 mg d(-1)) with respect to the effects of monensin on the production of three greenhouse gases (GHG), methane (CH(4)), nitrous oxide (N(2)O), a...

This study was undertaken to measure the effect of maximal stimulation of sodium pump activity on the rate of energy metabolism in mouse cerebral astrocytes. The rate of uptake of 3H-2-deoxyglucose (3H-2-DG) was measured in astrocyte cultures sodium-loaded either by incubation in a K+-deficient solution or by use of the carboxylic sodium ionophore monensin. Sodium-loading by the first method ca...

Twenty-four Holstein dairy cows were used to evaluate the single and combined effects of different levels of crude protein (CP) and monensin treatment during early lactation on blood metabolites, milk yield and digestion of dairy cows. The experiment was designed as a completely randomized block with a 3×2 factorial arrangement of treatments. The factors were three concentrations of CP suppleme...

This study investigated the relative contribution of ion-trapping, microsomal binding, and distribution of unbound drug as determinants in the hepatic retention of basic drugs in the isolated perfused rat liver. The ionophore monensin was used to abolish the vesicular proton gradient and thus allow an estimation of ion-trapping by acidic hepatic vesicles of cationic drugs. In vitro microsomal s...

Many feedlot finishing diets include wheat when the relative wheat prices are low. This study was conducted to examine the responses in ruminal pH and fermentation as well as site and extent of digestion from substituting soft or hard wheat for barley grain and to determine whether an elevated monensin concentration might decrease indicators of ruminal acidosis in feedlot heifers. Five ruminall...

Stimulation of astroglial glucose utilization by the Na(+)/H(+) exchanger monensin is only partially blocked by ouabain. The present studies show that monensin also raises intracellular pH in astroglia. Because increased pH stimulates phosphofructokinase activity, the ouabain-insensitive portion of the stimulation of cerebral glucose utilization (CMR(glc)) appears to be due to stimulation of gl...

Batch culture fermentations were used to determine the effects of avoparcin, lasalocid, monensin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, monensin + tylosin combination, and two new ionophore compounds (RO22-6924/004 and RO21-6447/009) on lactic acid and volatile fatty acid (VFA) production. Ruminal fluid from cattle fed a high alfalfa hay diet was incubated with glucose for 1...

Isometric force and "Ca efflux from the sarcoplasmic reticulum were measured at 19°C in frog skeletal muscle fibers skinned by microdissection . After Ca" loading, application of the ionophores monensin, an Na+(K+)/ H' exchanger, or gramicidin D, an H+ > K' > Na' channel-former, evoked rapid force development and stimulated release of ^"30% of the accumulated "Ca within 1 min, whereas CCCP (car...

To assess the nature of the aversion frequently shown by cattle for feed containing Rumensin, cattle were prepared with rumen cannulas and adapted to either a 93% ground alfalfa hay diet (n=12) or an 85% concentrate diet (n=12) They were assigned to one of three treatments for 6 hr/day for 7 days: 1) Basal feed and continuous intraruminal injection of a total of 50 ml alcohol (Control); 2) 250 ...

Twelve ruminally cannulated cattle, adapted to forage or grain diet with or without monensin, were used to investigate the effects of diet and monensin on concentration and duration of ruminal persistence and fecal shedding of E. coli O157:H7. Cattle were ruminally inoculated with a strain of E. coli O157:H7 (10(10) CFU/animal) made resistant to nalidixic acid (Nal(r)). Ruminal and fecal sample...