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Feeding and Managing High Nitrate Feeds

As grain and hay prices continue to climb, many producers are attempting to control feed costs by buying lower priced “alternative” forages.  These would include straws, stressed cereal grain hays, baled corn stalks, drought stressed forages and lower quality baled hay.

We’ve often discussed the concern about high nitrate forages and how to interpret analyses and manage higher nitrate feeds.  A brief discussion of sampling, interpreting reports and safely feeding higher nitrate feeds might help to avoid any potential problems.

Nitrate susceptible forages  

In most cases, the forages we are most concerned about are drought-stressed warm season annual forages, such as sorghum/sudan “cane” hays and millet hays. Weed species such as kochia, lambsquarters, sunflower and pigweed can also accumulate nitrates, so emergency feed resources should be watched closely. Finally, under extremely stressful conditions, additional crops such corn, wheat, oats and barley can also accumulate nitrates.  

From a management standpoint, the plant nitrates are generally located in the lower one-third of the stalk.  Raising the cutterbar when swathing or reducing the grazing pressure so animals are not forced to graze the lower portion of the stalk will help reduce the nitrate concerns. 

Nitrate testing

When testing forages for nitrate levels, pay close attention to how the nitrate levels are reported.  

Depending on the lab, nitrate levels may be described as nitrate (NO3), nitrate nitrogen (NO3N) or potassium nitrate (KNO3).  General nitrate recommendations are that NO3 levels of 6,000 parts per million (ppm), or one percent KNO3, or less are generally safe.  

Nitrate levels of 6,000 to 9,000 ppm, or one to 1.5 percent KNO3, are potentially toxic and should be fed with caution.  

Nitrate levels over 9,000 ppm, or 1.5 percent KNO3, are extremely dangerous and must be diluted and blended with other feeds.  

When testing hay for nitrates, be sure to sample from at least 10 bales, as there is a lot of variation in nitrate levels from bale to bale.  It is generally safer to feed susceptible forages to non-pregnant animals, and remember that nitrates remain in the plant, no matter how long the hay is stored.  

Feeding recommendations

Once you know the nitrate level of the forage, you can manage accordingly.  

The best situation is to keep the overall ration nitrate level below 6,000 ppm nitrate, or one percent KNO3.  This may mean blending or mixing hays.  When feeding nitrate-susceptible forages, the safest method is to tub grind and blend with low-nitrate hay.  If you are unable to tub grind, there are some important management considerations.

As mentioned before, feeding susceptible forages to growing, non-pregnant, animals is the safest route.  

When feeding, introduce the high nitrate feeds gradually.  Cattle do have a limited adaptation to higher nitrate levels.  This means that if you introduce the feed slowly, you will reduce the risk of having problems, but it definitely does not eliminate them.  

Also, making sure the overall ration is balanced, providing adequate energy by utilizing small amounts of supplemental grain, will also reduce the risk. 

If you are forced to feed bales of high nitrate feed, most recommendations are, after you have introduced it slowly, to feed some of both the high nitrate and safe hay each day. Generally feed the high nitrate feed first, followed by the safe feed.  

There is still the risk that some cows will eat only the high nitrate hay.  For example, dominant cows may push the thin or timid cows away from the better hay, forcing them to eat only the high nitrate forage.  You may reduce the risk of this by sorting the cattle into two groups – twos, threes and thin or weak cows and the adult cows.

When managing high nitrate forages, it is better to feed frequently and don’t allow the cattle to go hungry.  

Also, it is important to manage feeding closely, especially during severe weather.  If cattle go without feed for a day, they may go back and pick through the coarse stalks from previous feedings.  Those lower stalks are where most of the nitrate is located, increasing the risk of nitrate problems.

Finally, be aware of all sources of nitrates.  Some stock water sources can be high in nitrates, adding to the risk. 

Also, poor water sources may reduce the herd’s water consumption, also adding to the problem. 

While there are risks associated with feeding high nitrate feeds, weather conditions, hay availability and hay prices may limit any other alternatives.  Following a few basic guidelines and managing the cattle closely will definitely reduce the risk of nitrate problems.


SIDEBAR:
Recommendations for managing high nitrate forages

There are several things you can do to improve your safety when feeding nitrate susceptible forages.

Work cattle up slowly on nitrate forages.  Cattle will adapt to higher nitrate levels, decreasing the risk of having any problems.

Do not introduce hungry, naïve or not adapted cattle to nitrate susceptible forages. Work cattle up gradually.

Feed a balanced ration, supplying adequate energy and supplementation to meet vitamin A and E requirements.

Feed accurately, consistently and often to reduce risk.

Grinding and blending feed is the safest method.  If you are unable to grind, be sure to closely manage feeding so that all cattle have access to both low and high nitrate forages each day

Doing any of the above management will dramatically reduce risk.  

At UW in the 80s, they tried to induce nitrate toxicity with some cows by feeding 9,000 ppm nitrate forage as the only hay source.  They were unable to cause any toxicity and no abortions.  This is not going to happen every time, and as you can see, we don’t recommend this. 

If you manage the feeding closely, feeding the same time every day, working cattle up slowly so that they adapt, and providing adequate mineral and vitamin supplementation, as well as providing adequate energy in the ration, the risk is minimal with one percent KNO3 or lower feeds. 

NO3, ppm

KNO3, %

Effect

0 to 3,000 

0% to 0.30%

0.48 (I use .5 for simplicity)

Safe for all classes of livestock.

3,000 to 4,500

.30% to .45%

0.48 to 0.72

(0.5 to 0.75 rounded)

Usually safe for all classes of livestock under normal management.

4,500 to 6,000

.45% to .60%

0.72 to 0.96

(0.75 to 1.0)

Usually safe, consider feeding to growing animals, potential risk of early abortions if used as the only source of feed.  As levels approach 6,000 ppm, consider blending with low nitrate feeds to reduce risk.

6,000 to 9,000

.60% to .90%

0.96 to 1.44

(1.0 to 1.5)

Potentially toxic to cattle depending on situation; should not be the only source of feed, blend to 50% of the ration, keeping total diet NO3 levels below 6,000 ppm.

9,000 and above

0.90% and up

1.5 and above

Should not be fed to pregnant animals, be sure to blend at 1/4 to 1/3 of the ration.  Total NO3 should be below 6,000 ppm.