A review of feeding supplementary nitrate to ruminant animals: nitrate toxicity, methane emissions, and production performance

Abstract

Lee, C. and Beauchemin, K. A. 2014. A review of feeding supplementary nitrate to ruminant animals: Nitrate toxicity, methane emissions, and production performance. Can. J. Anim. Sci. 94: 557-570. The purpose of this review is to discuss the risks and benefits of using supplementary nitrate to reduce enteric methane emissions in ruminants based on the results of a meta-analysis. The meta-analysis confirmed possible nitrate poisoning triggered by higher blood methemoglobin levels with increasing nitrate consumption of ruminants: methemoglobin (%)=41.3×nitrate [g kg-1 body weight (BW) d-1]+1.2; R 2=0.76, P<0.001. However, acclimatizing animals to nitrate reduced the toxicity of nitrate: methemoglobin (%)=4.2×nitrate (g kg-1 BW d-1)+0.4, R 2=0.76, P=0.002. Animals fed nitrate reduced enteric methane emissions in a dose-response manner: methane [g kg-1 dry matter intake (DMI)]=-8.3×nitrate (g kg-1 BW d-1)+15.2, R 2=0.80, P<0.001. The reduction of enteric methane emissions due to supplementary nitrate was effec...