Triple Creek Journal: Feeding management for high nitrate hay

For many years, we made all our hay on the farm near Virgilina, VA.  Most of that hay was toxic KY-31 tall fescue.  This took a lot of effort, and we fertilized and pushed for a strong first cutting, which is more reliable than later cuttings due to the weather in our area.  We would spend much of the late spring and early summer putting up round bales and then getting them into storage.  I am a strong believer in good hay storage so nearly all of ours goes into a variety of sheds or on tires and under a tarp. It is a lot of work but worth every bit of effort.

Unrolling high nitrate hay as part of the diet can help cows adapt and safely use high nitrate hay.

As my parents started getting older it was harder and harder for me to get all the help I needed to make hay.  We also were in the midst of the “Kick the Hay Habit” craze, thanks to my friend Jim Gerrish.  After reading his book by that title, I realized that I was actually addicted to hay making, explaining how I could keep going and going during the hay season like the energizer bunny, well beyond what a reasonable day’s work is.  After being “strung out” on hay for a month or so, I was so exhausted that I was not interested in doing much for several weeks after we were done.  As a result, all other aspects of our late spring and early summer management was pretty poor. 

The first year I decided to address my hay problem, I quit cold turkey and didn’t roll a single bale that year.  It was a very difficult thing to do, but once I turned my attention to buying good hay and getting it in storage I realized that I had a lot of energy left for my grazing management and other tasks.  Today, we do make a limited amount of hay, but purchase most of our needs from several growers with whom we have developed a relationship.  I buy an arranged amount from each every year, and that way I am sure I will get the hay in the years when I need it worst.

This all works fine until there is a major drought and your hay suppliers don’t have enough to meet your needs.  The fall of 2019 was very dry, and followed a pretty poor spring growing season as well.  We didn’t have much stockpile for our normal winter grazing and fed through our normal hay supply by mid-winter. Our normal suppliers fulfilled our annual order, but they didn’t have any extra they could sell us.  Nothing feels worse than having a lot of cows and not enough hay! We searched and searched for hay, and bought a lot locally that was really expensive.  Most of what we found was suitable for mature cows, but some of it was terrible quality as well. 

To try to find hay as the winter went on, we had to go farther and farther away from home.  We found that there was still some hay available in southeastern NC, where many hog farms use their effluent to grow bermudagrasss and other forages.  This region usually has a big hay surplus, but it is about 150 miles away, so freight can get expensive.  In January 2020, I called one of the farmers I knew in Bladen County to see if he had hay.  He did at a very competitive price.  With freight it was still less expensive than hay we were purchasing locally. 

Because of the high amount of nitrogen used in those swine waste management systems, there is always a risk of high nitrate, especially in a dry year.  The farmer indicated his hay was usually low in nitrate, so I decided to get a load and test it once it got to our place.  This analysis showed a level of 0.6% nitrate ion, which is moderately risky for unadapted cows.  I knew we could work around that with our hay feeding system where we unroll bales so all the cows eat at the same time, so I ordered 3 more tractor trailer loads which would just about get us through to spring.

I was very relieved when the hay arrived, but when the forage analysis came back and it showed 1 to 1.1% nitrate, my heart sank.  This is a more difficult level to manage around with unadapted cows.  One thing to understand about nitrate is that cows can adapt to it.  If you feed an unadapted cow 1% nitrate hay there is a real risk of abortion and death.  However, in adapted cows, 1% is generally not a problem.  This adaptation process occurs because bacteria in the rumen can process nitrate to ammoinia which is used to synthesize microbial protein.  If these bacteria are not present at a high enough level, then nitrite can accumulate and be absorbed into the body where it is very toxic.  If you gradually increase nitrate level, then the bacteria that use it can increase in population, protecting you from a sudden increase in forage nitrate. 

We had no choice but to feed this hay to our 82 mature cows. We started by unrolling one bale a day of the 0.6% nitrate hay and 3 bales of low nitrate hay for three weeks.  Next we unrolled 1 of 4 of the 1% hay for a week, then 2 of 4 for a week, and finally 3 of 4 for the rest of the winter.  As we progressed through this sequence the cows improved in body condition because this bermudagrass hay was much better than hay we had been buying locally (13 to 18% crude protein and 60% TDN!). 

We put our bulls in about the time we started feeding this hay, and I knew our breeding outcome would tell the tale.  We didn’t have any dead cows or notice any other symptoms of nitrate poisoning, but the pregnancy results would reveal if we had caused a problem or not.

When the cows started calving the following October we had 67% of the cows calve in the first 21 days, another 17% the second 21 days and 5% in the third 21 days.  We sold some cows before calving that were confirmed pregnant (5%), and only had 7% that were open.  This is actually slightly better than we usually do, so it was clear that we were successful in managing that high nitrate hay without any problems.  

Purchasing hay is something many farmers in our area have turned to rather than making their own.  This makes a lot of sense, but to make it work, you need a regular relationship with hay growers that make good hay, you need to develop a good hay budget, and you need to be prepared to find additional hay early in the season when the hay and forage supply dictate.  As you work through possible hay suppliers, make sure you test for nitrate.  Nitrate is something you can manage around (within reason), so if you find nitrate is in the danger zone for unadapted cows, use adaptation to help them safely utilize the hay.  For more details, see Nitrate Management in Beef Cattle.

~ Dr. Matt Poore, NC State and Chair of The Alliance for Grassland Renewal

The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion.  For more resources or to learn more about the Alliance for Grassland Renewal, go to

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