Healthy cows perform better. Better performance can lead to greater production and profitability. Two things are vital when it comes to optimal rumen health: a stable, active, and healthy microbial population; and a suitable pH. The goal should be to minimize the time that rumen pH drops below 5.8. Thankfully, there are tips and tricks to combat the impact of heat stress on cow health.
National Accounts Manager, Ruminant Field Technical Specialist
Diamond V
Heat stress poses significant risks to both rumen and hoof health in dairy cows. With the potential to cause lameness and hinder overall performance, it is crucial to address the issue proactively. According to the Agriculture and Horticulture Development board, approximately one quarter of dairy cows may experience some degree of lameness at any given time, with the number of cows treated for lameness in early fall being more than twice as high as any other time of the year. This article explores the proactive measures that should be taken to prevent and detect lameness, focusing on rumen management and diet adjustments. By implementing effective strategies to combat the negative effects of heat stress, dairy farmers can safeguard their herd’s health and productivity.
MAINTAINING RUMEN HEALTH IN THE FACE OF HEAT STRESS
Heat stress in dairy cows can cause rumen dysfunction, intestinal damage, and immunity suppression. Higher temperatures can lead to decreased feed consumption, milk production, milk fat yield, milk quality, and reproductive efficiency. How does this happen? During times of heat stress, cows will stand more, eat less, and are at an increased risk of periods of low rumen pH, also known as subacute rumen acidosis (SARA). A lower rumen pH leads to a decrease in the number of bacteria that can digest fiber in the ration. In turn, there is less food energy available to the cow. Other rumen fermentation functions, blood parameters, and metabolites are negatively impacted by a cow’s physiological responses to heat stress. This is due in large part to heat stress-induced pH decrease and leaky gut. Leaky gut is a condition characterized by a weakening of the intestinal lining, allowing bacteria and pathogens to pass through.
The health of your herd starts with good rumen management. Healthy cows perform better. Better performance can lead to greater production and profitability. Two things are vital when it comes to optimal rumen health: a stable, active, and healthy microbial population; and a suitable pH. The goal should be to minimize the time that rumen pH drops below 5.8. Thankfully, there are tips and tricks to combat the impact of heat stress on cow health.
• Keep water filled, fresh, and clean: On average, a cow can consume up to 30 gallons of water on a normal day. When you factor in high humidity, that number can double. Make sure to increase water availability for your herd. Cows will not be as willing to walk longer distances in warmer weather. They must have constant access to cool, clean water in a location that is shaded or close to shade. By keeping water troughs cool and clean, your cows will have a better chance of beating the heat.
• Provide proper cooling: Cows have very little ability to sweat and cool themselves. Allowing access to misters, sprinklers, and fans can help. Look to see where the cows are congregating – this would be a great spot to install misters and sprinklers. To avoid water saturating the udder, don’t leave misters or sprinklers on for too long. Place your sprinklers on a timer to help avoid issues. Always remember to make sure misters are clean, and continuously provide proper airflow with fans. Air flow and constant water are critical to help your cows stay cool.
• Allow access to feed frequently: It is common for feed intake to decrease during hotter months. To keep their appetites up, make sure they have constant access to fresh feed. Feeding more frequently during cooler parts of the day keeps feed fresh, flavorful, and can increase intake. A tasty tip is to incorporate a covered feed structure that offers shade for cows, so they are more comfortable while eating.
By implementing heat abatement strategies, you can control the negative impacts of heat stress during the summer while working to prevent dairy cow lameness from showing up in the Fall.
MANAGING LAMENESS: THE IMPACT OF HEAT STRESS ON HOOF HEALTH
Heat stress is one of the biggest factors contributing to dairy cow lameness. Two of the main reasons are:
• Cows that experience heat stress tend to stand more, to increase their surface area to dissipate heat. This can cause trauma on their feet, allowing lesions to appear. If you have poor heat abatement, you are going to see sore and bruised feet.
• During heat stress cows will experience a decrease in energy and nutrient intake, which can lead to a reduction in hoof production and quality.
Lame dairy cows may experience diet changes, weight loss, limping, increased lying down time, pain, discomfort, changes in gait, and changes in posture. If a cow is showing any of these signs, it could mean lameness is taking its toll, and the necessary steps should be taken to treat the condition.
According to the University of California, locomotion scoring is a tool that determines the extent of lameness in order to determine if the problem is serious enough to justify attempting to alleviate it. Visually scored on a scale of 1 to 5, where a score of 1 reflects a cow that walks normally and a score of 5 reflects a cow that is three-legged lame, a locomotion score is made in a few seconds per cow.
When it comes to avoiding and treating lameness, one way is through regular hoof maintenance. Cow’s hooves should be trimmed at least twice a year, and regularly inspected and repaired. Regular hoof trimming provides an opportunity to check for hoof disorders, which commonly cause lameness, such as:
• Heel erosion
• Hemorrhaging
• Ulcer in the sole
• Ulcer in the whiteline
• Cracked hoofs
• Bruising of the sole
• Foot rot
• Digital dermatitis
Work with your nutritionist, veterinarian, and hoof trimmer to develop a lameness prevention program.
OPTIMIZING RUMEN HEALTH WITH POSTBIOTICS: A SOLUTION FOR LAMENESS CHALLENGES
Although it is vital to provide proper heat abatement strategies, there are also feeding strategies that may assist in reducing lost performance. Incorporating a proper postbiotic feed ingredient product can help stabilize the rumen, enhance microbiome populations, support gut integrity, and maintain intake and digestion – providing more available energy to the animal. Ultimately, this can result in greater profitability on the farm.
In fact, Dr. Lance Baumgard and team did a study at Iowa State University (Baumgard et al., 2020) to determine if a postbiotic moderated impacts of an induced heat stress (through thermal blankets) on production, metabolism, and immune/stress indicators of lactating dairy cows. They concluded that during heat stress, cows fed a postbiotic compared to control cows experienced:
• Reduced somatic cell count (SCC)
• Lower magnitude of heart rate increase
• Reduction in stress hormone of cortisol
• Increased circulating immune cells (white blood cells and neutrophils)
In another study done during the warm summer months on a large commercial dairy in Mexico (field trial 2020), the researchers looked to determine the effects of feeding a postbiotic to lactating Holstein dairy cows. They observed that cows fed a postbiotic had reduced body temperature compared to Control cows during the time of the day when body temperature was increasing.
Consult with your nutritionist about what ration changes might be appropriate for warmer temperatures, including the addition of a postbiotic to optimize rumen health.
In conclusion, heat stress in dairy cows can have serious negative impacts on both rumen and hoof health. In fact, according to Pennsylvania State University, in the United States, the prevalence of lameness on dairies ranges from 13 to 55%. However, there are strategies that can be implemented to help prevent and control the negative effects of heat stress. Proactive measures such as ensuring adequate water availability, providing proper shade, frequent access to fresh feed, and incorporating effective postbiotics can help in combating the harmful impacts of heat stress on cow health. It is important for farmers and industry professionals to prioritize heat abatement strategies to maintain optimal herd health and prevent dairy cow lameness from showing up in the fall.
About Jeff Wheeler, M.S.
As National Accounts Manager, Ruminant Field Technical Specialist, Jeff Wheeler is responsible for providing sales and technical leadership for Diamond V’s business in North America.
Wheeler attended the University of Georgia (UGA) in Athens, graduating with a B.S. in Dairy Science. He then continued his education at UGA and received his M.S. in Ruminant Nutrition. He brings over 20 years of dairy industry expertise to his position at Diamond V.
