Some preliminary observations on the nature of factors influencing the excretion of non-dietary faecal nitrogen by ruminant animals

Abstract

SUMMARY 1. When roughage rations of medium to high quality were given to steers and aduit sheep, the excretion of non-dietary faecal nitrogen was positively related to the intake of truly digestible dry matter. In these experiments no significant relationships were noted between non-dietary faecal nitrogen excretion and the intake of either truly digestible nitrogen or truly indigestible dry matter. 2. When concentrate rations containing 1.6–3.2% nitrogen were given to lambs weighing 19–27 kg the excretion of non-dietary faecal nitrogen was positively and significantly related to the intake of both truly digestible dry matter and truly indigestible dry matter, but not related to the amount of truly digestible nitrogen consumed. 3. Grinding and pelleting a grass ration for steers resulted in an increase in the excretion of non-dietary faecal nitrogen and bacterial + endogenous debris nitrogen, of 28 and 30% respectively, compared with the chopped material. 4. It is concluded that these responses reflect the dominating influence of nitrogen of microbial residues from the rumen and hind-gut on the excretion of bacterial + endogenous debris nitrogen and non-dietary faecal nitrogen.