Frost

What to Know About Grazing Frosted Forages

Mon, 09 Oct 2023 14:59:27 GMT

The first frost may be welcome for its fly-killing ability, but for cattle producers running cattle on annual forages, a few management steps this time of year can make sure that first frost doesn’t have the same effect on cattle grazing milo, sudangrass and sorghum varieties.

- Check your seed tag to know exactly what is in the field before grazing.

- When grazing, waiting five to seven days after a frost can help limit risk for both nitrate and prussic acid poisoning.

- With haying and cutting, prussic acid is not a concern, but nitrates can be worse. Remember to wait five days after a frost before cutting and raise the cutting height 6 to 8 inches to reduce risk.

- After a non-killing frost, new shoots or regrowth can be high in prussic acid and nitrates. If present, pull animals immediately and do not regraze until the plant has been fully killed or new growth is at least 18 inches high.

Dangers of Prussic Acid to Grazing Cattle

Following a frost, sorghum, sudangrass, sorghum-sudangrass hybrids, and milo have broken cell membranes that allow the formation of prussic acid. Prussic acid is a form of cyanide released from a compound called durrin that is naturally occurring in sorghum species. When ingested and broken down by the digestive system, the cyanide is released can quickly cause lethal results when consumed in high amounts. Monogastric species like pigs and horses can get prussic acid poisoning in extreme cases, but ruminants are more susceptible.

Keeping livestock out of these areas for five to seven days after a frost can limit the risk associated with prussic acid. Each time a new part of the plant is frozen, this five-seven day timer is reset until the entire plant has been killed. This can make grazing difficult this fall when freezing events occur regularly but are not enough to fully kill the plant.

New shoots and especially regrowth on previously frost-damaged plants have the highest concentrations of prussic acid. If you notice new shoots after a frost, animals should not be allowed to graze until the regrowth is 15-18 inches tall or a frost completely kills the plant. This can be especially tricky when warm temperatures follow an early frost.

Unless extremely high levels of prussic acid are present initially, haying or cutting a crop with prussic acid is not a concern. During the drying process, the prussic acid will volatilize and 50% or more of the initial concentration will be lost. Similarly, the fermentation process for ensiled sorghums will reduce prussic acid levels. If you are concerned about high levels of prussic acid in a silage or hay feed, samples can be sent to a lab for analysis.

Prussic Acid Formation

The relative risk for prussic acid formation*
Sudangrass varieties	Low to intermediate
Sorghum-Sudangrass hybrids	Intermediate
Forage sorghums	Intermediate to high
Grain sorghum	High to very high

_{*Adapted from Mark Sulc, The Ohio State University}

Nitrate Poisoning

Grasses are especially susceptible to nitrate poisoning risks. Slower metabolism following a stress like freezing allows nitrates to accumulate within the plant, specifically oats, sudangrass, and millets. Because nitrates do not dissipate like prussic acid, haying or green chopping is not recommended following a freeze and can be potentially dangerous.

Nitrates commonly concentrate in the lower portions of plant stems. Waiting five days before haying or chopping and keeping a cutting height of 6 to 8 inches will help mitigate risk. Like prussic acid, the ensiling process will lower nitrate levels of plants harvested for silage. If grazing, reducing the stocking rate and increasing the animals’ ability to selectively graze can lower nitrate risks. Pull animals off once the upper 2/3 of the plant has been consumed to avoid forcing animals to eat the lower portions of plants where nitrate risk is highest. This is not a good strategy for mixtures with sorghum species due to the prussic acid concerns discussed above.

Feeds that may contain high levels of nitrate aren’t necessarily unusable as long as proper action is taken to minimize risk. Send samples to a lab for analysis on those forages that are suspected to contain high nitrate levels. With these results, rations can be developed that limit the amount of high nitrate forage being fed, minimizing risk.

Avoiding Bloat

One final issue to keep an eye out for following a freeze is bloat. In high-quality forages like alfalfa, clover, and fresh small grain shoots, frost damage in the plant will rupture cell walls and make protein and minerals more readily available for one to two days. Many of the cover crop mixes contain some form of clover. Remember that ladino and white clover can cause bloat. These readily available proteins and minerals increase gas buildup in the rumen to the point animals cannot eliminate them by eructation (belching), creating bloat.

Fresh young plants and naturally higher protein species like legumes have a higher chance of causing bloat. In cover crop mixtures, grazing mature plants and making sure that mixtures don’t contain more than 50% high forage quality species like clover and alfalfa will help lower this risk. Introducing animals to suspect forages with a full stomach and limiting the time they are allowed to graze, supplementing in the meantime with hay, can keep animals from over eating, further exacerbating the problem. Providing free-choice grass hay and limiting animal grazing by strip grazing can help provide a more balanced mixture of plants and decrease the likelihood of bloat even further.

One final option that can be utilized in situations where bloat is a concern is a diet supplement. Bloat reducers like poloxalene or monensin can be effective if consumed regularly. To ensure uniform intake, these supplements can be mixed into a daily feed ration (poloxalene and monensin) or use a molasses or salt based block that cattle will regularly consume (poloxalene). Be sure to remove other salt and mineral choices if you choose to use this as a delivery method to ensure animals are regularly consuming the supplement.

Brutal Blast of Cold Set to Bring Widespread Freeze to the Western Corn Belt and Plains

Wed, 19 Apr 2023 18:43:48 GMT

Meteorologists say much of the country should brace for freezing temperatures this weekend and into early next week. The late April blast of cold weather doesn’t pose a big risk for the corn already planted in fields, but there are growing concerns about the potential damage to winter wheat.

USDA meteorologist Brad Rippey thinks the freezing temperatures could drop as far south as Texas.

“We are going to be watching at the end of this week on into next week some cold air that’s been kind of pulled up over Alaska in western North America swinging southward,” says Rippey. “And by the time we get to this weekend and on into early next week, we can easily see sub-freezing temperatures all the way down into north Texas. So, that means everybody north of that, including the northwestern half of Oklahoma, much of Kansas, all those areas should experience freezes.”

Friday night expected Kansas freezing temps. 22-27F West. 30-35F C and E. pic.twitter.com/p7M3yKjIxp
— Allen Motew (@QTweather) April 19, 2023

Rippey points out winter wheat is already heading in some of those geographies, including southern Oklahoma and parts of Texas.

“So, that is a concern where you overlap some freezing temperatures and heading winter wheat, with the part of the crop that’s even still viable, could be harmed by sub-freezing temperatures over the next few days,” says Rippey. “And unfortunately, that pattern seems like it’s going to continue. Although I think in time as we head into late April and early May, some of that colder air may spill more into the Midwest than the Great Plains. But this initial shot will deliver freezes likely as far south as at least the northern panhandle of Texas.

Rippey says he’s not as concerned about the corn crop that’s already planted since the crop either hasn’t emerged or the crop is still young enough that the growing point is below the soil.

“I think soils are warm enough to help insulate that growing point at this early stage. And as you move to the far north where it’s going to be really cold, we don’t have any corn planted yet. So I think we’ll be okay with the summer crops at this early stage,” says Rippey.

Western Belt freezing temps Friday night. pic.twitter.com/mlVKk4LYNp
— Allen Motew (@QTweather) April 19, 2023

Drew Lerner of World Weather has been keeping an eye on this weather pattern for more than a week. He originally warned about the possibility for a crop-damaging freeze late last week, but also said it was too early to see just how widespread the cold would be.

His latest forecast is colder than NOAA’s, but he points out crops may not be far enough along in potential problem areas.

“NOAA’s map is too warm, though, frost and freezes will occur southward into northern Oklahoma, southern Missouri and parts of Kentucky with Saturday’s coolest in the central Plains and Sunday’s and Monday’s coolest in the Midwest and middle Atlantic Coast States respectively,” says Lerner.

“Wheat, rye and oats are heading in the south of Oklahoma while canola is flowering. We are not expecting much more than frost in those areas, but it might be an area to watch. Most of the wheat in the lower Midwest is not far enough advanced to be impacted in a permanent negative manner,” says Lerner.

For the week ending April 16, 2023, there were 6.1 days
suitable for fieldwork, according to @USDA_NASS Winter wheat condition rated 60% very poor to poor, 26% fair, 14% good to excellent. Winter wheat jointed was 27%, behind 32% last year and 35% for the five-year average. pic.twitter.com/KkW31zYOdL
— KansasWheat (@KansasWheat) April 18, 2023

Winter wheat conditions are already in historically poor condition. Kansas’ crop is rated 60% poor to very poor, Oklahoma has 53% of the crop in the worst two categories and the Texas winter wheat crop is rated 52% poor to very poor.

“If you look at U.S. winter wheat conditions as a whole, as of April 16, we are seeing our lowest overall U.S. winter wheat conditions since the spring of 1996, and it’s really driven by these really abysmal numbers across the Central and Southern Great Plains,” says Rippey. “Right up and down the Central and Southern Great Plains everywhere, it’s almost every day that passes here, we’re losing more of this crop. Some of it never emerged. Some of it’s incredibly poorly established. And each passing day now in April, as the warmth, the wind and the dryness continue, we’re seeing lowering of those yield prospects and expectations for higher abandonment.”

From the dry weather and intense winds, to now the frigid air that could hit the crop into the weekend, winter wheat conditions continue to see weather challenges this year.

Late Frost and Freeze Warnings: What Does This Mean for Greening Pastures?

Fri, 20 May 2022 17:33:00 GMT

While many pastures endure an ongoing drought, some areas have been fortunate enough to catch timely rains to boost spring pasture growth. Unfortunately, forecasted frost advisories for this weekend may not be a welcomed event for cattle producers in the Midwest.

According to the National Weather Service Weather Prediction Center , areas in the western half of Nebraska, the Dakotas and much of Colorado, Wyoming and Montana might see temperatures drop below freezing Saturday night through Sunday morning.

What does this mean for new spring pasture growth?

“When conditions are moist, it may reduce the impact of a slight frost since temperatures change more slowly in wetter soil conditions than in dryer soils. The water outside of the plant can reduce freeze injury because the water will freeze before the water inside plant cells freeze,” says Victor Shelton, NRCS agronomist and grazing specialist in a news article .

The National Weather Service Weather Prediction Center forecasts a dry overnight during the coldsnap for much of the area.

The effects are compounded as temperatures rise quickly from below freezing levels.

“Warming up slowly after freezing conditions can reduce the effects of the freeze/frost. Abrupt, rapid warming, especially under dry conditions, aggravates frost injury. Then the chance of plant recovery is reduced,” Shelton says.

Temperatures are predicted to reach lows of 20s and 30s in these areas by early Sunday morning.

By end of day Sunday, temperatures may warm to highs in the 60s and 70s for parts of the region.

“Depending on the extent of stunting caused by heavy frosts or freezing, grass plants will feel some stress from this and may move slightly quicker towards reproductive stages. This will be intensified if pastures are also overgrazed. If you maintain adequate residual or stop grazing heights, and have good healthy soil, you probably won’t see much impact,” Shelton explains.

Shelton warns that close grazing on frost-damaged forage, especially early in the season, may reduce total production of the field for the year.

“For the most part, the adage of ‘short grass, short roots’ is very accurate. Not only are you potentially reducing production, but you also reduce the plants ability to seek out nutrients deeper in the soil profile and moisture and, most importantly, decreased its resilience,” Shelton says.

Shelton suggests being cautious of overgrazing by providing extra hay to cattle during these times to help with grazing pressure.

Planning to Frost Seed Pasture in 2016? Start the Prep Work Now

Sun, 15 Nov 2020 21:28:31 GMT

Frost seeding of pastures in late winter can be successful especially if the preparation is started in the fall.
By: Jerry Lindquist, Michigan State University Extension

Improving pastures with late winter frost seedings of certain legumes and grasses can be successful. If the planning and preparation is not started until seeding time however the odds of success may be diminished.

Frost seeding of clovers, birdsfoot trefoils, and some grasses such as annual and perennial ryegrass can be a very economical way to improve pasture forage growth and nutritional quality. Frost seeding is usually performed in late winter typically 40 to 50 days before grass growth begins in the spring. Frost seeding works best on clay and loam soils that experience soil movement with the freezing and thawing action that takes place that time of year. Part of the popularity of frost seeding is its ease of implementation and low cost. Producers have to simply buy the seed, broadcast the seed and watch it grow. There is no spraying, tillage, stone picking, nor loss of grazing for a summer that comes with re-seeding a new pasture. And in many cases the end result can be almost as good as a new seeding.

The common practice is to add a red or white clover seeding to a pasture when the legume percentage in the pasture is less than 40 percent. The existing grass pasture is not tilled or sprayed, just the clover seed is broadcast over top with the hope that the clover seedlings will compete and grow with the grass in the summer. Even thin stands of grass can be very competitive in the spring of the year. These existing grasses can out-compete the new seedlings for moisture, especially during a dry period in the spring, and the frost seeding may fail.

To give the frost seeded plants a better chance in the spring, over-grazing the grass stand in the fall is advised. When frost seeds are planned, it is the one time that Michigan State University Extension forage educators will advise you to weaken, or hurt the pasture stand in the fall before seeding.

Over-grazing does two things to help the success of the frost seeding. First it reduces the root food reserves of the pasture stand that will cause the grasses to be less aggressive in the spring. Secondly, by taking the grasses right down to two inches of stubble in late fall it removes the thatch layer on the soil surface, exposing more soil, which will lead to better soil-to-seed contact in the spring. Erosion is a slight risk as a result of this practice but the live roots and stubble remain in place preventing the risk of serious erosion. The set back of the stand is only temporary in the spring and the grasses will recover as the frost seeded plants start filling in by June. The benefit of letting the grazing animal be the plant retardant versus tillage and/or herbicide is quickly realized as pasture grazing does not skip a beat in the spring. The additional stand diversity that the new plants provide will benefit the grazing herd, beneficial insects and soil microorganisms in the pasture environment as well.

Frost seedings are beneficial when they work. To shift the odds of success more in your favor, weaken the pasture stands this fall that you are planning to frost seed.