Small intestinal sodium-glucose cotranshort in ruminants effects of adaptation to small intestinal starch

Three crossbred sieers (860 kg), 5 Angus sleers (500 kg), and I 2 crossbred lambs (43 kg) were allotted to two treatments in a completely randomi/ed design to determine the effect of small intestinal adaptation to a partial α-amylase starch hydrolysate (SH). Both sleers and sheep were fed ground fescue hay twice daily The crossbred steers were fed 10.0 kg/d, the Angus steers were fed 9.1 kg/'d, and the sheep were fed 0.8 kg/d. Adaptation to intestinal digestion of starch was accomplished by infusing SH abomasally (adapted) in steers (40 g/h) and sheep (6 g/h) for 7 d. The unadapted steers were infused ruminally and the sheep were fed lyophilized SH (144 g/d) twice daily On d 7 of SH infusion, steers were rendered unconscious, exsanguinated, and eviscerated. A 1-rneter section of jejunum \\as collected starting at the duodenojejunal flexure Sheep were overdosed on pentobarbital and the second meter of small intestine (measured from the pyloric sphincter) was collected. Brush border membrane vesicles were prepared from the tissues and sodium-dependent glucose uptake activity was measured using the rapid uptake/filtration technique. Brush border membrane enzymes, alkaline phosphatase and maltose, were enriched 8.4 and 8.5 fold in the vesicle preparation, respectively, and were not different between treatments. Adaptation increased (/' - 0.04) Na/glucose colransport activity 2.1 fold from 50.8 to 105 8 ±17 5 pmol·mg^-1·s^-1 in both cattle and sheep. Thesteer Na/glucose cotranspor activity (42 o pmol·mg^-1·s^-1) was lower (P = 0.01 ) than sheep (105.8 pmol·mg^-1·s^-1) and may reflect the longer lime in collecting the small intestine {> 45 vs < 10 min). This indicates Na/glucose colransport responds lo luminal carbohydrate in rummants.