Dietary nitrate and presence of protozoa increase nitrate and nitrite reduction in the rumen of sheep.

Nitrate ( ) supplementation is an effective methane (CH ) mitigation strategy for ruminants but may produce nitrite ( ) toxicity. It has been reported that rumen protozoa have greater ability for and reduction than bacteria. It was hypothesised that the absence of ruminal protozoa in sheep may lead to higher accumulation in the rumen and a higher blood methaemoglobin (MetHb) concentration.