Table 2. Summary of the studies evaluating effects of nitrate on ruminal methane reduction

Study no.	Authors	Year	Animal	Nitrate level (% of DMI)	Methane reduction (% of control)	References
1	Van Zijderveld et al.	2010	Sheep	2.6	32	[28]
2	Nolan et al.	2010	Sheep	2.5	23	[29]
3	Li et al.	2012	Sheep	2.3	34	[30]
4	El-Zaiat et al.	2014	Sheep	2.7	33	[31]
5	Hulshof et al.	2012	Beef cattle	2.2	32	[32]
6	Leng et al.	2012	Beef cattle	1.8	21	[33]
7	Newbold et al.	2012	Beef cattle	0.6–3.0	9–28	[34]
8	Troy et al.	2015	Beef cattle	2.2	12	[35]
9	Lee et al.	2015	Beef cattle	0.2–2.5	3–21	[36]
10	Duthie et al.	2018	Beef cattle	2.2	11	[37]
11	Rebelo et al.	2019	Beef cattle	1.4	19	[38]
12	Villar et al.	2020	Beef cattle	2	26	[39]
13	Van Zijderveld et al.	2011	Dairy cow	2.1	16	[40]
14	Guyader et al.	2014	Dairy cow	2.3	22	[41]
15	Guyader et al.	2015	Dry cow	2.3	28	[42]
16	Veneman et al.	2015	Dairy cow	2	22	[43]
17	Olijhoek et al.	2016	Dairy cow	0.5–2.1	6–23	[44]
18	Klop et al.	2016	Dairy cow	2.1	28	[45]
19	Meller et al.	2019	Dairy cow	1.5	17	[46]

DMI, dry matter intake.