Effects of nitrate supplementation and forage level on gas production, nitrogen balance and dry-matter degradation in sheep

Abstract

The present study was conducted to evaluate the effect of nitrate supplementation on dry-matter (DM) degradation and ruminal fermentation parameters by using in vitro gas production and in situ technique. In vitro gas production and in situ DM degradation in the presence or absence of nitrate were recorded at all incubation times. At all incubation times, diets incubated with nitrate gave a significantly lower gas production than did the other diets, except at 2-h incubation. Ruminal DM degradation did not differ among the experimental treatments. Furthermore, at most incubation times, total volatile fatty acids in diets containing nitrate were lower than those in the other treatments. Nitrate supplementation considerably increased gas production from the insoluble fraction, whereas it decreased gas production from the quickly soluble fraction, and potential gas production. Moreover, in all incubations, there were significant correlations between gas production and in situ DM-degradation parameters. The control diet had the greatest retained nitrogen content, but the diets containing nitrate had the greatest faecal nitrogen. The results showed that nitrate addition resulted in a lower gas production and volatile fatty acid production in in vitro assay. It was concluded that considering the strong posetive relationship between the two methodologies, the degradability parameters can be predicted from obtained gas production.