Drought Toxicity Risks for Cattle

A drought does more than shorten the grass. It changes the plants, the water and the cattle's behavior, and several toxic hazards rise at once. Planning before the dry spell deepens helps you avoid losses.

Key points

Drought raises several toxic risks at the same time.
Test stressed forage and hay for nitrate before feeding.
Check water daily for algae, salt and changes in cattle behavior.
Inspect pastures and purchased hay for toxic weeds.
Write a drought plan early and talk to your lender and FSA.

Why drought raises poisoning risk

When forage is short, cattle eat things they would normally skip. Stressed plants also change their chemistry. Some build up nitrate, some release more cyanide-producing compounds and some toxic weeds hold up better than grass in dry conditions.

Water changes too. Ponds shrink, salts and minerals concentrate and algae can bloom. Several risks stack up at the same time, which is why drought deserves its own plan.

Write down what you see on each pasture and pond as the dry spell develops, with dates and photos. Those notes help your vet and extension agent give specific advice rather than general warnings.

Forage hazards to know

Stressed forages such as sorghum types, corn, small grains and some weeds can hold dangerous levels of nitrate. Sorghum family plants can also release prussic acid after stress or frost. Do not feed or graze them without testing and professional advice.

Baled drought-stressed forage can still carry nitrate, since baling does not remove it. Ask your extension office how to sample and what the results mean for your cattle.

Water quality problems

Water becomes the neglected hazard when ponds are low and hot. Blue-green algae can form scum, and some blooms produce toxins that kill cattle quickly. High concentrations of salts, sulfate or other minerals in shrinking sources can cause illness or poor performance.

Check water daily. If it looks, smells or tastes different from normal, keep cattle away and ask your vet or extension office about testing. Never assume that dry-weather water is fine because it was fine last year.

Fence cattle off from any pond you cannot trust and haul clean water if you must. Hauling is a chore, but it costs far less than a die-off.

Scum, odd color or foul smell on pond water
Cattle refusing to drink or drinking much less
Dead birds or fish near the water
Sudden illness or death in cattle after drinking
Mineral crusts or heavy salt buildup around the edge

Toxic plants and bare ground

Overgrazed pasture invites weeds, and some of those are poisonous. Cattle that have little else to graze may eat them anyway. Walk pastures often during dry spells and compare what you see to a plant list from your extension office.

Hay purchased during drought is another way for toxic weeds to arrive. Ask the seller what is in the field and inspect bales before feeding.

Feeding decisions under pressure

Drought pushes ranchers to use unusual feeds: crop residues, byproducts, silage from stressed crops and purchased hay of uncertain origin. Each carries its own risk. A nutritionist can help you balance a ration that keeps cows in decent condition without introducing new hazards.

Do not experiment with urea or non-protein nitrogen sources on your own. Those products can be toxic when used wrong, and rates are for a nutritionist and the label to set, not a neighbor.

Planning ahead

Build a written drought plan before the dry spell arrives. It should cover when you destock or sort cattle, how you will watch water, who you call for forage testing and what triggers a change in feeding. Talk with your lender and USDA Farm Service Agency about assistance programs, which change over time and have deadlines, so ask early.

Keep body condition scores on your cows and watch for decline. Beef condition scoring uses a 1 to 9 scale, and your extension specialist can tell you the range to aim for at each stage of production.

Review your herd's vaccination and health plan in a drought year too. Stressed, thin cattle are more vulnerable to disease, so ask your vet whether anything should change.

Common mistakes and what to ask

Waiting too long to cut numbers, feeding stressed forage untested and ignoring water quality are the top errors. Ask your vet which drought-related problems are showing up locally, ask your nutritionist for a ration review and ask extension about water and forage testing. Call the vet right away for any sudden illness or death.

When to get help: Ask extension about forage and water testing, ask a nutritionist to review drought rations, and call your veterinarian immediately for sudden illness or death. For financial help, contact USDA FSA or your lender, since program terms change.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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