Utilizing high nitrate feeds safely

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Source: Manitoba Agriculture, Food and Rural Initiatives

Avoid feeding high nitrate feeds to sick, hungry, pregnant or lactating animals. These animals have a lower tolerance level to the nitrate then compared to healthy cattle. Make sure all animals have access to plenty of clean drinking water as this will help dilute the nitrate in the animal’s body.

To effectively dilute high nitrate feeds you must have a feed test done. Once you know how much is in the feed you can dilute it to the safe level of 0.5% nitrate (NO3) (dry matter basis). Different labs will express the nitrate levels in various ways. Below is a conversion table (Table 2) so that you can determine the level of nitrates in your forage.

Table 1.

% Nitrate DM basis Effect on Animal
0-0.3 Virtually safe
0.3-0.6 Moderately safe in most situations, if animals are stressed limit to 50% of the ration
0.6-0.9 Potentially toxic to cattle, do not use as sole feed source
0.9 and up Dangerous to cattle, often causes death

Animals will need to be adapted slowly to feeds containing nitrates. After a period of adaptation (one to two weeks) the animals tolerance level to nitrates increase and higher levels can be fed. However, if the animals are off high-nitrate feeds for a few days they will need to be re-adapted to the problem feed if it is to be fed again. Adaptation periods can be sped up by feeding limited amount of the ration frequently throughout the day instead of one large feeding once a day. As mentioned above, the low and high nitrate feeds need to be blended together to decrease the toxicity. This does not mean putting out one bale of low and one bale of high nitrate hay free choice because the animals may eat the high nitrate feed solely which would be toxic.

Feeding supplemental grain (2 to 5 lbs/head/day) with high nitrate forages can assist with the dilution of the nitrate level, as well the energy provided by the grain helps the rumen micro organisms convert the nitrite into ammonia which can than be excreted via the urine and feces. Balancing rations is important with feeding high nitrate feeds since the nitrate level can increase the animal’s requirements of vitamin A. If the ration requires supplemental protein avoid using non-protein nitrogen such as urea since this can make the situation worse.

Avoid feeding high nitrate feeds to sick, hungry, pregnant or lactating animals. These animals have a lower tolerance level to the nitrate then compared to healthy cattle. Make sure all animals have access to plenty of clean drinking water as this will help dilute the nitrate in the animal’s body.

To effectively dilute high nitrate feeds you must have a feed test done. Once you know how much is in the feed you can dilute it to the safe level of 0.5% nitrate (NO3). Different labs will express the nitrate levels in various ways. Below is a conversion table (Table 2) so that you can determine the level of nitrates in your forage.

Table 2. Conversion table

Unit Chemical Designation To convert to nitrate multiply by
Nitrate NO3 1.0
Nitrate-nitrogen NO3-N 4.4
Potassium nitrate KNO3 0.6
Sodium nitrate NaNO3 0.7

Prussic Acid Toxicity

Prussic acid is also known as hydrogen cyanide (HCN) and HCN levels exceeding 500 ppm on a dry matter basis can be very dangerous for livestock. To avoid problems do not allow hungry cattle to graze crops with prussic acid problems. Ensiling forages that have high levels of HCN can reduce the toxic compound as well as nitrate by as much as 50%. However, if the levels were extremely high to begin with this reduction may not be enough to avoid problems. Test all suspect feeds.

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