Cow Not Chewing Cud: Causes, Rumen Problems & What to Do

Cud chewing slows or stops when the rumen is not moving normally, when the cow is painful, or when fermentation is off balance. A mild case may follow a sudden feed change, spoiled feed, too much grain, or not enough effective long fiber. Merck notes that simple indigestion in cattle commonly causes decreased appetite and reduced forestomach motility, while high-grain feeding can lead to ruminal hypomotility or even atony. Diets lacking coarse roughage also reduce normal rumination.

More serious rumen problems include bloat, grain overload, and subacute ruminal acidosis. Bloat happens when gas cannot be released normally, and the left side may look distended. Grain overload can cause a static rumen, diarrhea, dehydration, weakness, and rapid decline. Subacute ruminal acidosis may be harder to spot early, but it is linked to inadequate fiber and feeding patterns that reduce rumination.

Not every cow that stops chewing cud has a primary rumen problem. Hardware disease, also called traumatic reticuloperitonitis, can cause pain, reduced rumination, fever, and reluctance to move. In fresh dairy cows, displaced abomasum and ketosis are also important causes, especially when cud chewing drops along with appetite and milk production. Esophageal obstruction, pneumonia, metritis, mastitis, and other systemic illnesses can also shut rumination down because sick cows often stop eating and the rumen slows with them.

Young calves are a little different. In milk-fed calves, abnormal milk entering the rumen can lead to ruminal drinking and acidosis rather than normal cud-chewing problems seen in adult cattle. That is one reason age, diet, and production stage matter when your vet works through the cause.

See your vet immediately if your cow has a tight, enlarged left abdomen, trouble breathing, open-mouth breathing, repeated lying down and getting up, collapse, choking signs, severe weakness, or sudden illness after getting into grain. Free-gas bloat with distress is an emergency, and esophageal obstruction with bloat is also considered urgent because pressure can build quickly.

Same-day veterinary care is wise if cud chewing has stopped for several hours and your cow is off feed, has a fever, seems painful, has very little manure, has diarrhea, shows a sharp milk drop, or recently calved. Fresh cows with reduced rumination may have displaced abomasum, ketosis, metritis, or another postpartum disorder that needs prompt treatment. Hardware disease is also a same-day problem because early treatment is more likely to help.

You may be able to monitor briefly while arranging guidance from your vet if the cow is bright, still drinking, has no abdominal swelling, no breathing trouble, and only had a mild recent diet upset. Even then, monitor closely for appetite, manure output, rumen fill, left-side distension, temperature, and whether cud chewing returns. If there is no clear improvement within a few hours, or if any new signs appear, move from monitoring to a veterinary visit.

Your vet will start with a full history and physical exam. Helpful details include when cud chewing stopped, recent feed changes, access to grain, calving date, milk drop, manure changes, and whether other cattle are affected. On exam, your vet may assess rumen contractions, listen and percuss for a ping, check hydration, temperature, heart rate, manure output, abdominal contour, and signs of pain or choke.

Depending on the findings, your vet may pass a stomach tube to relieve gas or check for obstruction, collect rumen fluid, run bloodwork, test for ketones, or use ultrasound. In suspected displaced abomasum, simultaneous percussion and auscultation can help identify the classic ping. If hardware disease is a concern, your vet may recommend a rumen magnet, antimicrobials, anti-inflammatory treatment, and sometimes imaging or surgery.

Treatment depends on the cause. Options may include oral fluids or transfaunation support, IV fluids, correction of acidosis, anti-inflammatory medication, treatment for ketosis or metritis, decompression of bloat, or surgery for displaced abomasum, severe hardware disease, or obstruction. Your vet will also discuss feed management, because restoring safe rumen function usually requires diet correction along with medical care.

Home care should support your vet's plan, not replace it. If your cow is stable and your vet agrees, remove grain and rich concentrates for now, keep clean water available, and offer good-quality long-stem hay or other appropriate roughage. Avoid force-feeding. Sudden diet swings can worsen rumen upset, especially after grain exposure or when acidosis is possible.

Watch the left side of the abdomen for swelling, and monitor appetite, manure output, attitude, temperature, and whether cud chewing returns. If you can safely observe rumen activity, note whether contractions seem absent or weak. Fresh cows also need close watching for milk drop, ketone smell, fever, vaginal discharge, or other postpartum changes that could point away from a simple rumen problem.

Keep the cow in a quiet area with secure footing and easy access to water and feed. Reduce stress and unnecessary movement if she seems painful. Do not give over-the-counter medications, magnets, drenches, or mineral products unless your vet tells you to, because the right choice depends on the cause. If bloat, breathing trouble, choke signs, or worsening weakness develop, stop home monitoring and contact your vet immediately.