Water is a vital nutrient that we take for granted. We assume that if there’s water available for the livestock that we’ve taken care of that requirement. However, there are a number of factors that can negatively affect water quality and livestock performance. Earlier I talked about an easily identifiable factor of water quality, cyanobacteria. This time, I’ll cover one you can’t see, nitrates.
Nitrates are utilized by rumen bacteria to produce ammonia. Nitrate/nitrite toxicity happens when higher than normal amounts of nitrates are consumed. This causes a build of nitrites in the rumen, which are absorbed into the bloodstream. Nitrites convert hemoglobin to methemoglobin, rendering it unable to transport oxygen. So the blood is able to transport much less oxygen.
Signs of nitrate toxicity include: chocolate colored blood, bluish or chocolate colored mucus membranes, difficulty breathing, noisy breathing, salivation, tremors and staggering. Unfortunately the first sign of a problem is a dead animal as symptoms can appear 30 minutes to 4 hours after ingestion. If you suspect nitrate poisoning, it’s important to call your veterinarian immediately and tell them what you suspect. Nitrate poisoning is treatable, but only if your veterinarian is prepared. A quick way to check a suspect animal is to give it a small cut and check the blood color.
All water sources have the potential to contain nitrates. Nitrate sources include run off from heavily fertilized (manure, commercial fertilizer, human waste) fields and pastures as well as decomposing organic matter. Surface water sources such as stock damns, ponds, ditches and poorly sealed, shallow wells are more likely to have higher nitrate levels, due to run off. Evaporation of stock dams, ponds, etc. without replenishing the water level will concentrate the level of nitrates.
Nitrate levels in water and forage can have an accumulative effect in the rumen. Testing water sources, and forages, is the only way to know what the total nitrate level is. Nitrate levels can be reported as either nitrate-nitrogen (NO3-N) or nitrate (NO3). Your county extension service can assist you with proper testing techniques as well as interpreting the results.
NO3-N in water
- 0-100 ppm Safe
- 101-300 ppm Use with caution, consider level in feed
- >301 ppm Potentially toxic
NO3 in water
- 0-440 ppm Safe
- 441-1300 ppm Use with caution, consider level in feed
- >1301 ppm Potentially toxic
