The Effect of Energy Supplementation on Intake and Utilisation Efficiency of Urea-treated Low-quality Roughage in Sheep II. Rumen Kinetics and Acetate Clearance Rate

Inadequate supply of glucose or glucogenic substrates to the body tissues can affect metabolism of absorbed acetogenic metabolites from the gut and therefore, influence feed intake in ruminants. This study investigated the effect of energy supplementation on rumen kinetics in the gut, and the acetate clearance rate in the body tissues of sheep fed low quality basal roughage. A basal diet consisting of urea-treated mixture of wheaten chaff and barley straw (3:1 DM) containing 22.2 g N/kg DM was used. Four Merino cross wethers weighing 45 +/- 4.38 kg fitted with permanent rumen and abomasal cannulae were allocated to four treatments in a 4x4 LSD. The treatments were basal diet (E(0)), or basal diet supplemented with sucrose (112.5 g/d) administered intraruminally (E(R)), abomasally (E(A)), or via both routes (50:50) (E(RA)). There was no difference (p>0.05) in the rumen liquid kinetics parameters between the four dietary treatments. However, there was a trend of animals supplemented with sucrose wholly or partly through the abomasum having lower faecal DM and therefore poor pellet formation, and low pH. Although the glucogenic potential of the fermentation products absorbed from the rumen was increased (p<0.001) by intra-ruminal supplementation with sucrose (E(R) and E(RA)), there was no significant difference (p<0.05) in acetate clearance rate between the four dietary treatments.