How barometric pressure affects cattle performance on grain

We’ve all seen cattle go off their feed or break with respiratory disease just before a weather system hits. One of the key culprits behind this pattern is something often overlooked: barometric pressure.

When barometric pressure drops quickly—usually ahead of a cold front or storm system—it puts stress on a cow’s respiratory system and immune function. This makes cattle more susceptible to illnesses like Bovine Respiratory Disease (BRD), especially in feedlot environments where animals are already under pressure. Appetite can drop, behavior changes, and animals with subclinical infections may suddenly show symptoms.

Why do treatment rates increase when pressure falls?

Low barometric pressure slightly reduces oxygen availability and can cause discomfort in the sinuses and lungs—especially for animals with existing respiratory issues. This physiological stress can affect rumen motility and decrease appetite. Cattle are very sensitive to these environmental changes, and even subtle shifts can disrupt normal feeding behaviour.The reciprocal issue is that empty, hungry cattle may then hit feed hard and over-eat. This disrupted feeding pattern stresses the already pressured rumen buffering system of cattle on grain rations and can lead to sub-acute rumen acidosis (SARA) and associated production loss and reduced disease resilience. This is felt keenly by many Merriwa-Cassilis grain-assisted enterprises using self-feeders, because self-feeders provide ad lib ration access, and lower roughage length & volume, compared to bunk-style feeding yards.We can’t control the weather, but here’s what you can do:

Monitor weather forecasts for sudden pressure changes - you can monitor barometric pressure on the Iphone app.

• Minimize stress (avoid processing or transport during major shifts).

• Ensure vaccinations are current and booster timing is optimal.

• Be ready to treat early—don’t wait for an outbreak to spread.

Stay safe and keep them healthy,