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Animal Sciences

CAFNR

Thermal Aid

Beef Cattle Pasture Tips • Beef Cattle Feedlot TipsGrazing Dairy TipsFree-Stall Dairy Tips

Look for the Clues to an Impending Heat Stress Crisis:

First Clue: Predicted hot weather following precipitation. It is the combined temperature and humidity that determines the severity of heat stress. Days in the high 80’s or 90′s following a precipitation event can be extremely stressful, especially if the wind speed is below miles per hour for extended periods of the day.
Second Clue: Monitor the upper critical temperature limits of your animals. Consider this limit has been reached when the Temperature-Humidity Index reaches 80.
Third Clue: Evening weather forecast for overnight temperatures to remain above 73°F. A potential heat stress crisis situation exists for cattle when there is little or no night cooling. Watch for days following nights in which the ambient temperatures do not drop below 70°F. Feedlot losses have been commonly reported when 3 or more consecutive days with Temperature Humidity Index values above 80 have been tied together with nights in which the temperature stayed above 70°F.
Fourth Clue: Observing cattle will tell you when they are becoming uncomfortable from heat. The cattle will start to move … walk around the pen looking for an area of the pen that is more comfortable. They will start to slobber and their respiratory rate will increase above 75 breaths per minute. They will begin to elevate their head to make it easier to breathe. They will position their body to minimize their exposure to the sun, generally facing the sun.

Beef Cattle Pasture Tips

No Stress

• Moniter Weather Forecasts
- Air temperature and relative humidity: Normal performance losses begin at an air temperature of 75-77F; Normal performance of the newborn calf begins to decrease at 82-84F.
- Watch for the day where THI consistently is above 84.
- Watch for nights with little nighttime cooling (THI stays above 70).
- Days where there is little wind (below 5mph).
• Identify High Risk Animals
- Newly arrived cattle that may already be stressed.
- Cattle on endophyte infected pastures.
- Black of dark-hided cattle.
• Develop Shade on Pastures - Trees are preferable: They allow for greater air movement; Scatter sunlight better and cool the air; Cows prefer natural shade over artificial.
• Create Cooling Ponds
- Fresh water is better.
- Water consumption increases: 3-5lb per lb dry matter intake at 59 to 77F; 4-10lb per lb dry matter intake at 77 to 95F; 8-15lb per lb dry matter intake at greater than 95F.
• Things to Observe for Signs of High Stress
- Animal behavior during heat stress: Body may be aligned with solar radiation; Animal will seek shade; More time is spent standing; Crowding around water trough and standing in ponds; Animals more agitated or restless.
- Respiration rate: Normal respiration rate is 40 or less breaths per minute; In general, respiration rate in full sun starts to increase above 75F; If 10% of the animals have a respiration rate between 70-120 breaths per minute with rapid panting, drooling and no open mouth, all handling and movement should stop; There is danger of death at 120-160 breaths per minute.
- Feeding acivity: Dry matter intake decreases. 1. 3-5% at 77 to 95F; 2. 10-35% at greater than 95K.
- Core body temperature if possible: Normal core temperature is 101.3 - 103.1. 1. 107.6 is critical. Rectal temperature in full sun starts to increase above 77F; Skin or surface temperature especially in the sun will not be helpful.

Alert

• Avoid Handling After 8am
- Moving cattle elevates body temperature one-half to three and one-half degrees F, depending on cattle temperature and time. During heat stress periods, if cattle must be handled, work them in the early morning (prior to 8 am and absolutely not after 10 am) and in a shaded facility if possible.
• Provide Fresh Clean Water
- Add additional water tank space, so that cattle have access to at least five gallons per hour.
• Make Plenty of Shade Available
- If trees are not available, add artificial shade: Cows begin to use shade as air temperature goes above 77-81F (25-27C).
• Control Flies
- Flies cause cattle to bunch and disrupt cooling. Commercial sprays or treated ear tags work best.
• Provide a Quality Trace Mineral Block or Mix
- It is important to replace electrolytes: Increased sweating increases loss of water and electrolytes; Increased water consumption will increase excretion of urine.

Danger

• Remove Animals From Endophyte Infected Pastures
- Flies cause cattle to bunch and disrupt cooling. Commercial sprays or treated ear tags work best.
• Shade Water Troughs to Keep Water Temp Down
• Provide Supplemental Feed at Night

Emergency

• Do Not Move Animals
• Keep Animals Off Endophyte Infected Pastures
• Move Shade and/or Water Closer Together
• Set Up Sprinklers to Spray the Animals

« Beef Cattle Feedlot Tips

No Stress

• Moniter Weather Forecasts
- Air temperature and relative humidity: Normal performance losses begin at an air temperature of 75-77F; Normal performance of the newborn calf begins to decrease at 82-84F.
- Watch for the day where THI consistently is above 84.
- Watch for nights with little nighttime cooling (THI stays above 70).
- Days where there is little wind (below 5mph).
• Identify High Risk Animals
- Newly arrived cattle that may already be stressed.
- Finished of nearly finished cattle.
- Black of dark-hided cattle.
- Cattle that have been sick in the past.
• Prepare a Heat Stress Feeding Program - Diets should have a reduce energy level. Ration energy level reduction will reduce fermentation and the associated heat production. This is done by reducing the grain concentration in the ration. You can add fat back to the diet to prevent loss of gain.
• Provide Mounds for Cattle in the Pens
- Mounds, the taller the better, help prevent cattle from bunching and will enhance cattle exposure to air movement (5 to 10 mph wind for optimum cooling in cattle). Cattle use mounds like bleachers with animals finding spots that minimizes the air-flow blockage by an adjacent animal.
• Add Additional Shade
- The shade structure should provide approximately 20-40 sq. ft. of floor space per feedlot animal. Shade height should be in the range of 7 to 14 ft.

Alert

• Remove Manure Build Up
- Remove manure build up from around waterers, feed bunks, and under shade. Build up should not exceed 1 inch in depth.
- Shift to a Late Day Feeding Schedule: 70% or more of the daily feed should be given two to four hours after the peak ambient temperature of the day. Moving to a late day feeding schedule may minimize the sub-clinical acidosis.
• Make Sure There is Good Air Flow
- Lots should have minimal trees, other buildings, or obstructions within at least 50 feet of all sides. Cut all weeds or tall grass within a 150 foot perimeter of the yard.
- Move cattle if there is a windbreak stopping air flow during hot weather. For example, a 10-foot windbreak will create calm air for a distance of 100 feet (ten feet for every one foot of windbreak height).
• Provide Additional Fresh Clean Water
- Providing 5 ½ inches of linear space per animal can be lifesaving in feed yards and ensure that all cattle can get water when needed. A 1,100-lb steer will need to consume approximately 24 gallons of water per day.
- Above 80°F, cattle may require approximately two gallons of water per hour per 100 pounds of body weight.
• Control Flies and Parasites
- Flies cause cattle to bunch and disrupt cooling. Removing weeds and brush within 100 ft of pens and spraying the shaded areas of building with a residual insecticide will help control flies.

Danger

• Avoid Handling or Moving Animals After 8am
- Cattle that must be handled during hot days should spend no more than 30 minutes in the handling facility.
• Reduce Stocking Density
- Keep stocking densities below100 percent with 30 inches of feed bunk space per cow to encourage DMI while keeping cows cool and comfortable.
• Modify Diet to Maintain Feed Intake
- Keep stocking densities below100 percent with 30 inches of feed bunk space per cow to encourage DMI while keeping cows cool and comfortable.
- For optimum efficiency, maximize the use of low heat increment feeds like fats and oils. This can be followed by grains – high quality roughages (corn or cottonseed hulls) and finally high fiber roughages.
- Corn and concentrates may produce less heat of fermentation and, as a result, less of a heat load. Concentrates may lead to acidosis.
- Heat production peaks about 3-4 hours after feeding.
- Feed smaller amounts more frequently and more in the evening and night.
• Wet the Animals and/or Ground
- Wetting 20 sq. ft of pen space or more per animal will allow sufficient room for all animals to get relief from the heat.
• Grind light-colored Bedding (straw or hay) into pens
- This will provide a cooler surface to rest on than the dark-colored pen surface.

Emergency

• Do Not Move Animals
- Processing cattle can elevate their body temperature by 0.5 to 3.5F.
• Spray Animals with Water if Possible
- Wet the animals using large droplets not a fine mist. Wetting is more efficient when there is wind and low relative humidity. Night sprinkling may be effective.
- Greater evaporation occurs during the day when the humidity is possibly lower.
• Consider Wetting the Ground
- Wetting 20 sq. ft of pen space or more per animal will allow sufficient room for all animals to get relief from the heat.
• Shift to a Low Heat Increment Diet
- Consider a lower energy 'storm ration' to reduce heat production in cattle. Higher fat diets have lower heat increment and also help in heat stress situations.
• Shade as Much of the Pens as Possible
- For emergency situations to reduce mortality risks, more than 40 sq ft/head can be beneficial.

« Grazing Dairy Tips

No Stress

• Moniter Weather Forecasts
- Air temperature and relative humidity: Normal performance losses begin at an air temperature of 75-77F; Normal performance of the newborn calf begins to decrease at 82-84F.
- Watch for the day where THI consistently is above 84.
- Watch for nights with little nighttime cooling (THI stays above 70).
- Days where there is little wind (below 5mph).
• Identify High Risk Animals
- Newly arrived cattle that may already be stressed.
- Cattle on Endophyte Infected Pastures.
- Cattle that have been sick in the past.
• Develop Shade on Pastures - Trees are Preferable
- They allow for Greater Air Movement.
- Scatter Sunlight Better and Cool the Air.
- Cows Prefer Natural Shade Over Artificial.
• Create Cooling Ponds
- Fresh Water is Better.
- Water Consumption Increases.
- 3-5lb per lb dry matter intake at 59 to 77F.
- 4-10lb per lb dry matter intake at 77 to 95F.
- 8-15lb per lb dry matter intake at greater than 95F.
• Things to Observe for Signs of Heat Stress
a. Animal behavior during heat stress: - i. Body may be aligned with the solar radiation
- ii. Animal will seek shade. - iii. More time is spent standing. - iv. Crowding around water trough and standing in ponds. - v. Animals more agitated or restless.
b. Respiration rate: - i. Normal respiration rate is 40 or less breaths per minute. - ii. In general, respiration rate in full sun starts to increase above 75F. - iii. If 10% of the animals have a respiration rate between 70-120 breaths per minute with rapid panting, drooling, and no open mouth, all handling and movement should stop. - iv. There is danger of death at 120-160 breaths per minute.
c. Feeding activity: - i. Dry matter intake decreases. - 1. 3-5% at 77 to 95F. - 2. 10-35% at greater than 95F.
d. Core body temperature if possible: - i. Normal core temperature is 101.3-103.1F. - 1. 107.6F is critical. - ii. Rectal temperature in full sun starts to increase above 77F. - iii. Skin or surface temperature especially in the sun will not be helpful.

Alert

• Move Cows to Paddock Closets to the Dairy with Access to Sprinklers
- Moving cattle can elevate their body temperature by 0.5 to 3.5F.
- The shorter the walk to the milking parlor the better
• Delay Milking Time Until Later in the Day
- Milking prior to sunrise and near sunset or after will reduce heat stress level.
- During heat stress, cattle will tend to eat more during the cooler times of the day
• Control Flies
- Flies cause cattle to bunch and disrupt cooling.
- Eliminate fly breeding areas weekly. Commercial sprays or treated ear tags work best.
• Pregnant Cows Need Extra Care
- These animals have a higher level of heat production and stress.
- It takes about a week to reduce heat production in the heat with adaptationi:
- Only after a week will heat stress be less and the cow get relief
• Provide a Quality Trace Mineral Block or Mix
- a. It is important to replace electrolytes:
- Increased sweating increases loss of water and electrolytes.
- Increased water consumption will increase excretion of urine.

Danger

• Allocate Best Paddocks for Grazing Overnight.
• Make Sure Holding Pens are Comfortable
a. Do not leave cows in holding pen for more than 35-40 minutes before milking.
b. Cows may be cooled in the holding pen by short-term sprinkling: - Approximately 0.5 to 3 minutes spraying with 0.05 inches of water per cycle should be just enough to soak the skin; - Water should not run on the udder because it might result in bacterial contamination; - Blowing air on to the animal during this process will increase cooling; - Floor should be grooved or have a rough surface so that the cows will not slip; - A slight slant on the floor will help with drainage and prevent water accumulation.
c. Shade over the holding area will help the animals stay cool; - Another shade covering over the area where the sun enters the holding area would be helpful
• Wetting Animals as They Exit the Milking Parlor is Helpful
- The additional evaporation of water at this time will help to dissipate additional heat.
More sweat glands are located in the shoulder area than the rump region so the sprays should be directed to this area.
• Delay Milking Until Later in the Day
- Milking prior to sunrise and near sunset or after will reduce heat stress level.
- During heat stress, cattle will tend to eat more during the cooler times of the day.
• Provide Supplementary Feed at Night
- Dry matter intake decreases 10-15% when air temperature goes above 78F.
- Maintenance requirements may increase 25% under severe heat stress when feed intake decreases.

Emergency

• Let Animals Move at Their Own Pace
- a. Moving cattle can elevate their body temperature by 0.5 to 3.5F.
- The more comfortable the walk to the milking parlor the better.
• Spray Animals with Water if Possible
- The water should not be cold because it will reduce heat loss. Preferably mild to lukewarm.
- Greater evaporation occurs during the day when the humidity is possibly lower: - Avoid night sprinkling.
• Reduce Time Spent in Holding Pens
- Do not leave cows in holding pen for more than 35-40 minutes before milking.
- Bring up smaller groups to ensure as little time as possible is spent in holding pens.
• Setup Sprinklers and Shade in Holding Pens
- 36 to 48” fans should be spaced 8ft apart and 8ft apart. Fans should be 30° from the vertical. Sprinklers should spray every 15 minutes (Foggers should spray at 200-225 psi).
• Cool Exit Lanes
- Spray the animals as they leave the parlor (An electric eye or motion sensor works well). Water troughs in travel lanes and in holding pens.
• If more than 5 cows out of 10 have a respiration rate above 100 breaths per minute, then immediate steps should be taken to decrease heat stress.

« Free-Stall Dairy Tips

No Stress

• Moniter Weather Forecasts
- Air temperature and relative humidity: Normal performance losses begin at an air temperature of 75-77F; Normal performance of the newborn calf begins to decrease at 82-84F.
- Watch for the day where THI consistently is above 84.
- Watch for nights with little nighttime cooling (THI stays above 70).
- Days where there is little wind (below 5mph).
• Identify High Risk Animals
- Newly arrived cattle that may already be stressed.
- Cattle on Endophyte Infected Pastures
- Cattle that have been sick in the past.
• Prepare a Heat Stress Feeding Program
a. Decrease forage to concentrate ratio (may need to increase bi-carb to help with concentrate). Supplement fat such as whole cottonseed, soybean, tallow, or a combination. May also raise the vitamins in the diet.
b. High quality forages should be used if available. Energy density of diet should be increased.
c. Low fiber feed traditionally results in less heat increment than high fiber diets.
d. Diets high in grain and low in fiber should be used for high-producing dairy cows: - Care should be given to adjust these diets properly because this combination might result in digestive problems.
Buffers such as sodium bicarbonate and magnesium oxide can help when feeding these types of diets.
Proper minerals should also be used in these diets: - 1. Recommendations include increasing potassium to 1.3-1.5%, sodium to 0.5-0.6%, and magnesium to 0.3-0.4%
• Check Water Tanks for Adaquate Fresh Water
a. Troughs should be clean so there is no algae growth.
b. Water should not be cold but cool or slightly warm: - Ground temperature is good.
c. Water should be available where they rest and preferably under shade. d. Cows will not walk more than 100 feet in the field during extreme heat. e. Ideally, there should be 2 feet of available trough space for 15 cows: - Water flow rate through the trough should be 3 to 5 gallons per minute; - At least 3 inches should be available on the bottom for the cow’s muzzle.
• Avoid Overcrowding for Extended Period
a. Floor space may be 19-65 ft2 (1.76-6.04m2)per animal.
b. As the environment becomes more hot and humid, the floor space should be increased.
• Shade and Cooling Should be Around the Feed Trough
a. Animals will be more interested in eating if the feed is shaded.
b. Water sprays should be directed away from the feed: - Low pressure sprays (10 psi) work well; - Fans should be off at first or the mist will be blown out of the area; - They are then turned on after a period of time; - Concrete floors should be sloped 1.5-4% and grooved to provide animal traction on the slippery surface.
c. Fans can be used to keep the water off the feed: - Also keep excess water off the floor and animal udder.

Alert

• Monitor Weather Forecasts
- If no relief as noted for No Stress within 48 hours, additional cooling approaches are needed.
• Shift to a Late Day Feeding/Milking Schedule
• Install Fans to Air Flow
• Control Fly Population
- Flies cause cattle to bunch and disrupt cooling. Removing weeds and brush within 100 ft of pens and spraying the shaded areas of building with a residual insecticide will help control flies.
• Do Not Leave Cows in Holding Pen for More Than 35-40 Minutes before Milking
• If Dry Matter Intake or Milk Production has Decreased 10% or More, Then Steps Should be Taken to Decrease Heat Stress
- A 25% reduction in feed intake and milk production is severe, and death may occur.

Danger

• Make Sure Holding Pens are Comfortable
- Do not leave cows in holding pen for more than 35-40 minutes before milking.
- Cows may be cooled in the holding pen by short-term sprinkling: - Approximately 0.5 to 3 minutes spraying with 0.05 inches of water per cycle should be just enough to soak the skin; - Water should not run on the udder because it might result in bacterial contamination; - Blowing air on to the animal during this process will increase cooling; - Floor should be grooved or have a rough surface so that the cows will not slip; - A slight slant on the floor will help with drainage and prevent water accumulation.
c. Shade over the holding area will help the animals stay cool: - Another shade covering over the area where the sun enters the holding area would be helpful.
• A Device for Wetting Animals as they Exit the Milking Parlor is Helpful
- The additional evaporation of water at this time will help to dissipate additional heat.
- More sweat glands are located in the shoulder area than the rump region so the sprays should be directed to this area.
• Modify Diet to Maintain Feed Intake

Emergency

• Run Smaller Groups at Their Own Pace
• Run Water Over the Shade or Roof of the Barn
- Outer surface of metal roofs could be painted white or aluminum to reflect solar radiation outward and not toward the animals.
- Durable insulation can be placed just below the roof to reduce radiation of heat downward toward the animals.
• Spraying Cows with Mild to Lukewarm Water to Increase Heat Loss
- Greater evaporation occurs during the day when the humidity is possibly lower: - Avoid night sprinkling.
• Animals Will Eat Very Little in This Condition
- Attempt to feed at night.
• Increased Sweating in the Heat Increases Loss of Water and Electrolytes
- Remember to replace electrolytes: - Work with nutritionist to provide more sodium and potassium.
b. Cows need much more water under these conditions: - Provide extra
• Cool Exit Lanes
- Spray the animals as they leave the parlor (An electric eye or motion sensor works well). Water troughs in travel lanes and in holding pens.
• Do Not Leave Cows in Holding Pen for More Than 35-40 Minutes Before Milking

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