Buttercup in Pastures

The UK Forage Specialists have had several calls on the safety of yellow buttercup in KY pastures and asked Dr. Megan Romano to comment on the potential risks to horses.

Buttercup

According to the current USDA PLANTS database, nearly 30 different species of Ranunculus, or buttercups, are found in Kentucky. Leaves, flowers, and stems of have a sharp, pungent taste and the plants are generally avoided by grazing livestock.

Some Ranunculus species contain ranunculin, a compound hydrolyzed to protoanemonin when the plants are damaged – for example, when they are chewed. Protoanemonin is a vesicant, causing blistering of the skin, mouth, and digestive system. Those Ranunculus species with the highest ranunculin concentrations are the most toxic. Damage to the plant cells also occurs when buttercups are cut and dried in hay.  Hydrolysis of ranunculin to protoanemonin likely occurs as the plants dry. Protoanemonin then forms anemonin, which is not a vesicant. Dried Ranunculus plants are therefore expected to lose toxic potential fairly rapidly, although specific research has not been published to confirm this. The risk posed by Ranunculus species in Kentucky is minimal if there are plenty of other forages present – animals avoid grazing the unpalatable fresh plants, and the dried plants appear to be much less toxic.

Buttercups can cause mouth pain and blisters, drooling, oral and gastric ulcers, colic, and diarrhea. Horses are probably the most sensitive species to the gastrointestinal effects of Ranunculus species. These effects can be severe if buttercups are ingested in large quantities, but their acrid taste usually deters further grazing. Clinical signs are typically seen only in animals forced to consume buttercups when they have nothing else to eat.

A few anecdotal reports have suggested an association between the presence of Ranunculus species in the pastures and abortions in cattle and horses; these reports are unconfirmed, and attempts to reproduce the disease have been unsuccessful. Bur buttercup (Ceratocephalus testiculatus) can cause significant illness but this plant occurs primarily in the Western U.S. and is not a true buttercup, as it belongs to a different genus.

A review of UKVDL records over the last 13 years found no cases of livestock deaths attributable to Ranunculus. It is possible, however, that cases of colic or diarrhea have unknowingly been caused by ingestion of Ranunculus species and were never attributed to the plant. Buttercup toxicosis poses the greatest risk to starving animals with nothing else to eat; it can be easily prevented by providing animals with adequate forage. Because animals avoid grazing Ranunculus, it proliferates in overgrazed pastures. Overgrazing can be prevented by maintaining appropriate stocking rates.

According to UK publication “Broadleaf Weeds of KY Pastures, AGR-207” Late February or March is the time of the year to spray for buttercup control. Maintaining good grass cover prevents many weeds including buttercup from germinating in fall or winter. Resting pastures and not overgrazing are key to improving pasture health. Thin stands with bare areas or that contain summer annual grasses like crabgrass can be overseeded with a pasture mix in September. Be sure to soil test every 2-3 years and apply amendments based on soil test recommendations. In most horse pastures, nitrogen is most beneficial in the fall to improve root density and thicken stands.  For more information, check out our publications Establishing Horse Pastures or Soil Sampling and Nutrient Management of Horse Pastures. Additional information on buttercup in pastures and control methods can be found in here.  ~ Dr. Ray Smith, Dr. Megan Romano and Krista Lea

 

Clip Pastures to Reduce the Risk of Ergot

The UK Horse Pasture Evaluation program has observed ergot bodies in headed out tall fescue pastures and hay fields in the last two weeks on several central KY farms.

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Photo: Dr. Jimmy Henning

Claviceps fungal spores are found in the soil of much of the US and can infect the seeds of many grasses, particularly when there is frequent and heavy rainfall during seedhead development.  This infection results in the growth of sclerotia (also called ergot bodies) instead of a healthy seed and look similar to mouse droppings. The sclerotia contain concentrated levels of many ergot alkaloids, a number of which are similar to the major toxin found in endophyte-infected tall fescue and cause symptoms similar to fescue toxicosis in all livestock. Since ergot bodies are not associated with the endophyte found in infected fescue, they can also be found in endophyte free and novel endophyte tall fescue varieties.

To reduce the risk of ergot poisoning by grazing animals, keep pastures clipped to remove seedheads. Check tall fescue hay and bedding for presence of ergot bodies. Because of the raking and baling process, ergot bodies in hay or bedding are rare, but can occur. ~ Dr. Cynthia Gaskill, Dr. Ray Smith and Krista Lea.

Read a full publication on ergot here.

 

National Forage Week: June 16-22

The American Forage and Grassland Council is excited to celebrate the 5th Annual National Forage Week on June 16-22, 2019 as an effort to raise awareness to the importance and impact of forages. As the leader and voice of economically and environmentally sound forage focused agriculture, AFGC understands the impact of forages on the world and wants to share that knowledge by focusing our education efforts during National Forage Week.

Have a fun forage fact you would like to share? Email to tina.bowling@afgc.orgNFQ.png

Managing Pastures this Summer

Setting a sustainable stocking rate.  Setting the proper stocking rate, defined as animals per acre per year, is a primary determinant in grazing system success.  A stocking rate set too high will result in the degradation of the entire grassland ecosystem.  A stocking rate that is set too low will result in wasted forage and decreased profitability.  In addition, stocking rate also impacts the amount of conserved forage that will be needed.  A stocking rate set too high will result in less grazing and more hay feeding.  Stocking rate depends on many factors such as forage species, soil type, soil fertility level, and grazing management.  In general, supplying each cow-calf unit with 2 to 3 acres of grazable pasture is a good place to start.  In most cases it is better to start with a lighter stocking rate that can be gradually increased as soil fertility increases and grazing management improves.

Grazing management.  Controlled grazing or rotational stocking is a management practice that allows producers to determine how closely pastures are grazed and how long they are rested between grazing events.  Leaving residual leaf area and resting pastures between grazing events allows pastures to re-grow quicker and produce up to a third more forage in a given grazing season (Sollenberger, et al., 2012).  Some forage species are better adapted to close and frequent grazing than other.

Soil fertility.  The soil fertility can have a profound impact on both the productivity and botanical composition of pastures.  When fertility is low, improved forage species like tall fescue and orchardgrass and red and white clover become less productive and weed species that are better adapted to lower fertility fill in the gaps. Fertilizer and lime applications should ALWAYS be based on a recent soil test.  If funds are limited, apply lime if needed.  Lime not only reduces soil acidity, but also makes nutrients in the soil more available to plants.

Hay and silage remove large quantities of nutrients.  In contrast to grazing, making hay or silage removes large quantities of nutrients.  These nutrients must be replaced to maintain soil fertility, and stand health and productivity.  Each ton of hay that is removed from a field takes with it approximately 15 lb of phosphate and 50 lb potash.  In a good year a tall fescue-clover mix may yield 4 tons per acre and remove 60 lb phosphate and 200 lb of potash.

Successful pasture management requires an integrated approach that involves the soil, plant, and animal.  This means we need to select well adapted forage species and manage them in a manner that creates a healthy and vigorous sod that excludes weeds from our pastures.  When we combine this with clipping and the judicial use of herbicides, we will have a winning combination! ~ Dr. Chris Teutsch. See the full article in the upcoming June issue of Cow Country News.

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Broom sedge is often an indication of low soil fertility. In this photo Greg Brann discusses approached to reclaiming broom sedge infested pastures. 

 

Forage Timely Tips: June

  • Continue hay harvests. Minimize storage losses by storing hay under cover.
  • Clip pastures for weeds and seedheads as needed.
  • Slow rotation allowing for a longer recovery period.
  • Use portable fencing to decrease paddock size and increase paddock number.
  • Do NOT grazing below the minimum desired residual height.
  • Crabgrass, a warm-season annual grass, can provide high quality summer grazing. Remember crabgrass needs some annual soil disturbance to keep coming back.