Effects of 3-nitrooxypropanol on methane production using the rumen simulation technique (Rusitec)

The purpose of this study was to evaluate the effect of different doses of 3-nitrooxypropanol (NOP) to a backgrounding diet on methane (CH4) emissions using the in vitro rumen simulation technique (Rusitec). 3-Nitrooxypropanol is an enzymatic inhibitor that has consistently reduced CH4 emissions in sheep, dairy and beef cattle (up to 59% reduction on a long term basis). Two Rusitec apparatuses each equipped with 8 fermenters were used in a completely randomized block design with 2 blocks (apparatus) and 4 treatments: 0, 5, 10 and 20 mg of NOP. Within each apparatus, 2 fermenters were randomly assigned to a treatment. Treatments were supplied daily with 10 g of diet (6 g of barley silage, 3.5 g of barley grain and 0.5 g of supplement; dry matter [DM] basis). The experiment included an adaptation period without treatment supplementation (8 days) and a treatment period (7 days) with NOP addition. 3-Nitrooxypropanol did not affect dry matter (DMD; P = 0.79) or organic matter disappearance (OMD; P = 0.50) but reduced CH4 production (mL g−1 DM) by up to 86.2% (P 0.12); however, that for methanogens in the solid phase was reduced (P