High temperatures and humidity are tough on cattle and productivity. In addition, stress starts to compound in animals, as pink eye, summer pneumonia and flies can also threaten cattle performance.
According to Iowa State University, once temperatures reach above 80 degrees Fahrenheit, beef cattle endure physiological stress dealing with their heat load.
Heat abatement, or the reduction of heat stress, along with managing other summer stressors, is critical for beef producers to minimize production losses and keep cattle healthy all summer long.
Preparing for Heat Stress in Cattle
Cattle sweat very little - about 10% of the human rate. To cool themselves, cattle will dissipate heat through respiration or panting, radiating heat from their bodies with vasodilation (pushing blood to the body's surface for heat removal) and reducing feed and forage intake.
Cattle generate heat in their rumen during fermentation, which causes core temperatures to rise even more. They also typically congregate at water troughs or under trees during the summer months, making it hard for heat to escape, escalating the impact of heat stress.
Cattle’s ability to dissipate heat depends on:
Air temperature and relative humidity
Energy level in the feed ration
According to the Journal of Dairy Science, economic losses from heat stress to the United States cattle industry are estimated at more than $370 million a year. The dairy industry experiences more than double that loss at $897 million.
What Are the Signs of Heat Stress in Cattle?
Cattle experience visible and internal signs of heat stress as they attempt to dissipate heat.
Visible Signs of Heat Stress
Internal Signs of Heat Stress
Open mouth breathing and panting
Productivity stops as energy is diverting to returning the body to homeostasis, decreasing performance
Inflammation and immune activation
Decreased feed intake and increased water intake
Lower reproduction rates
Decreased activity, lying down
Reduced average daily gain (ADG)
Increased insulin levels
Agitation and restlessness
The USDA states that production losses have already begun once cattle start experiencing visible signs of heat stress.
How to Manage Heat Stress in Cattle
Cattle producers can prepare for and combat heat events with a combination of management practices and tools such as:
Ensuring cattle have access to plenty of fresh water. Add more tanks before a heat event to help alleviate congregation around main water tanks.
Using droplets, not mist. Make sure the droplets of misters are large, not small. If the droplets are too small, they can create added humidity, worsening heat stress.
Providing shade. Shade structures should be open and 8 to 14-feet tall to allow for proper ventilation. They should provide between 20 and 40 square feet per animal, depending on animal size.
Fresh feed. Heat also impacts feed quality and increases the growth of bacteria, mold and yeast, making feed less appetizing to cattle. Ensure cattle have fresh feed in a feedyard setting.
Supporting their immune system. Heat stress equals gut stress. More than 70% of the immune system is contained in the gut. As heat stress erodes immunity and gut health of cattle, which can lead to disease challenges and performance losses, it is essential to support their immunity. Research shows that feed additives using essential oils and capsicum can help boost immunity, provide antioxidant support and help cattle reduce the impact of heat stress.
Related: Why Heat Stress Equals Gut Stress in Cattle
Controlling Summer Pink Eye
Beef producers know the threat of pink eye is more prevalent in the summer.
Also known as infectious bovine keratoconjunctivitis (IBK), pink eye is a highly contagious disease that severely impacts productivity and is incredibly painful to cattle.
According to the University of Wisconsin, pink eye is primarily caused by the bacteria Moraxella bovis, which produces a toxin that attacks the eye. It is commonly understood that Moraxella bovis is the cause of traditional IBK or summer pink eye.
What Causes Pink Eye in Cattle?
Several things can predispose cattle to pink eye. The eyes have natural defense mechanisms to thwart infection and damage. However, eye irritants or trauma allow pathogens to pass through the eyes’ defenses and get to the cornea.
Predisposing factors associated with pink eye include:
Dust and sand
Weeds, tall grass and stalks
Other animals, overcrowding from heat stress and tails swishing from flies
Physical hazards like barbed wire or trauma during handling and transport
Pink eye occurs in stages as the eye tries to repair itself. Stage two occurs when blood vessels spread throughout the cornea to help with healing. The eye becomes bright pink, explaining how the term ‘pink eye’ was derived.
What’s the Impact of Pink Eye?
The University of Illinois estimates the cost of pink eye to the U.S. cattle industry at more than $150 million per year due to decreased weight gain, milk production, treatment costs and permanent scarring to the eye that reduces sale price. Recent studies show a 17 – 65 lb. weight loss from pink eye, with treatment costs exceeding $100 per incident.
How to Manage Pink Eye in Cattle
Many beef producers use pink eye vaccines with varying levels of success
in the summer months. Yet, the best way to reduce the incidences of pink eye is to manage the associated predisposing factors. Face flies can carry pink eye from animal to animal, so fly control methods are critical. Additionally, ensuring animals are not overcrowded or near hazards, reducing heat stress and handling them as little as possible can help. If pink eye cases are discovered, immediately isolate cattle away from the herd and treat until the infection is gone.
Related: How Garlic Can Help Minimize Pink Eye in Cattle
Preventing Summer Pneumonia in Calves
Summer pneumonia in nursing calves is another challenge for beef producers to watch out for. This problem can come on quickly and be unpredictable, with the first sign often being sick or dead calves.
The University of Nebraska identifies summer pneumonia as a respiratory disease in pre-weaned calves on pasture. While the direct cause of summer pneumonia is unknown, researchers and veterinarians have found a few direct correlations between outbreaks and these varying factors:
Poor colostrum quality from cows lacking in nutrition