Search

Two experiments were conducted with growing male rats to determine the effects of 120 ppm of dietary sarsaponin (S) on nitrogen (N) metabolism when urea or protein are added to the diet. Growth, feed efficiency, N digestibility and balance, urinary N and ammonia-N (NH3-N), and cecal urease and NH3-N were measured. Growth and feed utilization were unaffected by dietary S. Adding urea or protein to the diet increased apparent N digestibility and increased urinary-N excretion. Urea did not affect N balance, whereas growth, feed utilization and N balance were maximized with 22% compared with either 16 or 28% dietary protein. Urinary NH3-N excretion was decreased by S when urea was added to the diet but was not affected when fed with increasing dietary protein. Cecal urease was decreased by S when urea was added or when the protein level was increased in the diet; effects on cecal NH3-N varied between the two experiments. Plasma urea-N was decreased by S. It is concluded that S has minor effects on N metabolism in rats and that NH3-N formation or excretion is only marginally affected by dietary S. If S decreases NH3-N level in confinement facilities, it is concluded that the effect is after the waste material is excreted by the animal, perhaps through reduced urease activity.

Twelve ruminally and abomasally cannulated lambs (27 ± 1.16 kg) and 16 intact lambs (28 ± 1.49 kg) were used in two trials to study the influence of dairy biomass (a cheese processing wash water sludge) as a protein source in medium-concentrate diets. In Trials 1 and 2, lambs were assigned to one of three concentrate diets containing 0, 10 or 20% biomass with an additional positive control diet in Trial 2. Biomass provided 27.4 and 52.7% of the CP in 10 and 20% biomass treatments, respectively. Diets were similar in N content and were fed at 3.5% of initial BW (as fed). Apparent ruminal OM and N digestibilities were lower (P< .10) in lambs receiving 20% biomass than in lambs fed 0 or 10% biomass. Postruminal N digestibility was higher (P< .10) for lambs fed 20% biomass. Apparent OM and N digestibilities in both trials were reduced (P< .10) in lambs receiving 20% biomass. The molar proportion of acetate in the rumen was higher (P< .10) in lambs receiving 10% biomass compared to lambs fed other treatments. Plasma urea N concentration (mg/dl) was higher (P< .10) at 3 and 9 h after feeding in lambs receiving 10 and 20% biomass compared with control lambs. Although N retention was unchanged, fecal N excretion was higher (P< .10) and urinary N excretion was lower (P< .10) in lambs consuming 10 and 20% biomass treatments. Non-ammonia N and feed N flow (g/d) were higher (P< .10) in abomasal contents of lambs consuming 20% biomass vs other dietary treatments but N digestibility was decreased. In conclusion, digestibility was decreased and site of N digestion was altered by feeding biomass.