Cressleaf groundsel, or yellowtop, is a butterweed that’s toxic to cattle. It’s native to Florida, North and South Carolina, Georgia, Indiana, and Texas, and is also found in states including South Dakota and Ohio. This weed grows in prairies and floodplains in clay and loam soils. Below we’ve summarized what you need to know about this toxic weed that could prove fatal to your herd, according to research by Ohio State University Extension.
Pyrrolizidine alkaloids are the main toxins found in cressleaf groundsel. In cattle these toxins are known to cause liver disease and produce symptoms like listlessness, decreased appetite, diarrhea, anorexia, and even sensitivity to sunlight, or photosensitization, in severe cases. Cressleaf groundsel has also caused abortions in cattle.
Most beef cattle will eat between 2 and 2.5 percent of their body weight in dry matter each day. Since Pyrrolizidine alkaloid toxins in cressleaf groundsel are cumulative when hay contains more than 5 percent of this harmful weed in dry matter weight, enough of it can be consumed within 20 days to kill an animal in your herd.
Cattle are 30 to 40 times more likely to die from the consumption of cressleaf groundsel than animals like sheep or goats. Calves and younger cattle are more susceptible to death than older cattle, but at high enough doses, this weed can be lethal to all age groups.
With some plants toxicity decreases as they dry, but that’s not so with cressleaf groundsel. Even when this plant is dried and baled its toxins are not diminished. Ensilaging will decrease the concentration of toxins, but it won’t eliminate them. Livestock producers with high concentrations of cressleaf groundsel in their fields may do well to bale first cutting and throw it away to avoid poisoning their livestock.