Nitrate toxicity in annual forages: Survey of beef producer perspectives and samples submitted to a commercial testing laboratory in Nebraska

Abstract

The objective was to assess the prevalence and management of nitrate toxicity when beef producers use annual forages. A survey was distributed online and advertised via extension outlets in Nebraska and Kansas. Additionally, examination of the various annual forage samples submitted to Ward Laboratories Inc. (Kearney, NE) for nitrate-nitrogen (NO 3 -N) analysis was conducted to determine the frequency that various annual forages have been evaluated for nitrate content. Most survey respondents (n = 107/115; 93%) were from the midwestern United States, and 85% indicated that they use annual forages in 3 or more years out of 5. These producers were more ( P = 0.02) likely to test annual forages fed as hay (53%) than grazed (38%). There was a tendency ( P = 0.09) for more producers to suggest that they have had nitrate toxicity issues with annual forage pasture (34%) than with hay (24%), though the majority had not experienced issues (62%) with either. When small grains, millet, and sorghum × sudangrass were evaluated, fresh forage (<26% DM) had greater ( P < 0.01) nitrate content than dry forages (>84% DM). Overall, 48% of the fresh brassica samples, 23% fresh annual grasses, and 5% of the dry annual grasses were considered at risk for causing nitrate toxicity as they exceeded 2,100 mg of NO 3 -N/kg of DM. These data suggest that annual forages are infrequently tested for nitrates and that the majority of survey respondents have not experienced nitrate toxicity when using annual forages.