Why Spring Kills More Cattle Than Any Other Season
Spring is the most dangerous season for toxic plant poisoning in Texas. Hungry cattle coming out of winter, toxic plants that green up before grasses do, and limited forage availability — it's a recipe for disaster. Knowing the spring-specific risks and putting preventive measures in place can save your herd and your investment.
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Why Spring Is So Dangerous
The Perfect Storm
- Toxic plants emerge first - Many poisonous species green up 2-4 weeks before grasses
- Forage is limited - The "spring gap" occurs when winter stockpile is gone but grass isn't ready
The Spring Gap
The "spring gap" or "hungry period" typically occurs:
- South Texas: Late January - February
- Central Texas: February - March
- Panhandle/North Texas: March - April
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High-Risk Spring Plants
Locoweed: Spring Is Peak Season
- May be the only green forage available
- Cattle begin eating and become addicted
- Early spring is when most locoweed poisoning begins
- Green material in manure when grass isn't growing
- Depression, weight loss, staggering
- Supplement with hay during spring gap
- Scout for locoweed before turning out
Oak: Buds and Young Leaves
- Emerge before grasses in many areas
- Shinnery oak (West Texas) is especially problematic
- Cattle may browse heavily during forage shortage
- 2-3 weeks of highest risk during bud break
- Risk decreases as leaves mature
- Reduced urination
- Swelling (edema)
- Provide supplemental hay
- Consider calcium hydroxide supplementation
Cocklebur: After Flooding
- Cocklebur seedlings emerge in low areas
- Cotyledon (2-leaf) stage is extremely toxic
- Cattle access low areas as water recedes
- Stock tank overflow areas
- Low spots in pastures
- Recently flooded fields
- Scout for cocklebur seedlings
- Wait until plants have several true leaves
Larkspur (Where Present)
- Young plants are most palatable
- Alkaloid levels highest in early growth
- More common in mountain regions, but present in some Texas areas
- Know if larkspur is present on your ranch
- Delay grazing until plants are mature
Spring Risk Assessment
Before Turnout Checklist
- [ ] Note locations of locoweed patches
- [ ] Check oak bud development stage
- [ ] Assess grass growth status
- [ ] Check low areas for cocklebur seedlings
- [ ] Identify any new toxic plant populations
- [ ] Is there at least 3-4 inches of green grass?
- [ ] Have you compared grass growth to previous years?
- [ ] Is forage quality adequate to meet cattle needs?
- [ ] Are they excessively hungry from winter?
- [ ] Are any animals showing signs of previous locoweed exposure?
- [ ] Have you introduced new, naive cattle?
Management Strategies
Delay Turnout
- Wait until grasses are actively growing
- Aim for 3-4 inches of green grass minimum
- Better to feed hay a few more weeks than lose cattle
Supplemental Feeding
- Feed before cattle go out on pasture
- Continue until grass is adequate
- Consider protein supplementation
- Fills cattle before they graze
- Provides buffer during critical period
- Cheaper than dead cattle
Strategic Pasture Rotation
- Avoid locoweed-infested areas until grass is growing
- Rotate to higher-risk areas later in spring
- Keep "clean" pastures for spring turnout
Monitor New Cattle
- They may sample unfamiliar vegetation
- Watch new cattle especially closely
- Keep new arrivals on safe pastures initially
Weekly Spring Monitoring Protocol
Week 1-2 After Turnout
- Look for cattle browsing low plants
- Watch for early signs of locoweed consumption
- Monitor water source areas
- Green material in manure (when grass isn't dominant)
- Staggering or depression in any animals
- Cattle congregating in oak-heavy areas
Week 3-4
- Continue monitoring locoweed areas
- Watch oak consumption if still in bud break
- Check cocklebur status in low areas
Throughout Spring
- Late frosts can set back grass, extending risk
- Drought conditions maintain hungry period
- Rain can trigger cocklebur germination
Regional Spring Considerations
South Texas
- Nightshades emerging early
- Oak species budding earlier than other regions
Central Texas
- Locoweed in western portions
- Cocklebur in creek bottoms after spring rains
West Texas / Panhandle
- Shinnery oak in sandy areas
- Spring gap can be extended
- Drought years are especially dangerous
East Texas
- Earlier green-up reduces spring gap somewhat
- Perilla mint locations should be noted (for fall)
- Wetter conditions favor some toxic plants
Emergency Response in Spring
If You Suspect Spring Poisoning
- Identify what they've been eating
- Provide clean hay and water
- Call veterinarian
- Isolate affected animals
- How long have cattle been on this pasture?
- What symptoms are you seeing?
- How many animals are affected?
- What have they been fed recently?
Treatment Resources
- Cyanide treatment kit (if using sorghum-sudan)
- Methylene blue (for nitrate poisoning)
- Activated charcoal
Economic Considerations
Cost of Spring Losses
| Loss Type | Typical Cost |
|---|---|
| Death loss per cow | $1,500-2,500+ |
| Locoweed-related performance loss | 30-50% of value |
| Abortion from toxin exposure | Value of calf + rebreeding costs |
| Treatment costs | $200-1,000+ per case |
Cost of Prevention
| Prevention Measure | Typical Cost |
|---|---|
| Supplemental hay (2 weeks) | $20-40/head |
| Delayed turnout | Hay cost only |
| Pasture scouting | Time investment |
| Toxic plant control | Varies by method |
Case Example: The Early Turnout
- One cow developed bloody diarrhea
- Investigation showed cattle had been browsing oak buds heavily
- Grass was only 1-2 inches—not enough forage
- Two recovered with supportive care
- Rancher moved cattle back to dry lot
- Resumed hay feeding for 3 more weeks
Bottom Line
- Spring is highest risk - More toxic plant deaths occur in spring than any other season
- Wait for grass - Don't turn out until 3-4 inches of green grass is growing
- Feed through the gap - Hay is cheap insurance against dead cattle
- Scout before turnout - Know what toxic plants are in your pastures
- Locoweed starts in spring - Early consumption leads to addiction
- Oak buds are toxic - Young leaves and buds are most dangerous
- Watch flooded areas - Cocklebur seedlings appear after water recedes
- New cattle are vulnerable - Monitor introduced animals closely
Related Resources
- Complete Guide to Texas Toxic Plants
- Locoweed: Identification and Prevention
- Oak Poisoning in Cattle
- Cocklebur and Pigweed Dangers
References
- Texas A&M AgriLife Extension. (2024). "Seasonal Toxic Plant Risks."
- Burrows, G.E. & Tyrl, R.J. (2013). Toxic Plants of North America. Wiley-Blackwell.
- Ralphs, M.H. (2002). "Ecological Relationships Between Poisonous Plants and Rangeland Condition."
- Knight, A.P. (2001). A Guide to Plant Poisoning of Animals in North America. Teton NewMedia.
- Texas Veterinary Medical Diagnostic Laboratory. (2024). "Seasonal Poisoning Case Data."
"The first green of spring can be the last green your cattle see"
