1998 Volume 1998 Issue 35 Pages 5-11
Three rumen cannulated sheep offered corn silage (CS) and chopped timothy hay (TH) ad lib. were used to examine the effect of an altered rumen fluid outflow rate on microbial nitrogen (MN) yield. Four levels (0, 1, 2 and 3l/d) of artificial saliva was infused into the rumen of sheep offered the two diets. The intraruminal infusion level had little effect on the rate constant of rumen fluid outflow and rumen fluid volume in sheep offered the two diets. The rate constant of rumen fluid outflow tended to be higher in TH group than CS, while rumen fluid volume was higher (P<0.05) in CS than TH group. Rumen fluid outflow (l/d) did not differ (P>0.05) across the treatments. The MN yield was markedly greater (P<0.05) in TH than CS group. The effect of saliva infusion level on MN was not detected. Available energy and N supply were higher for TH compared with CS feeding, this resulted in an increase in MN yield.