Managing Heat Stress…

annecattlebunk.jpgA combination of events provided motivation for the writing of this post.  I received a number of requests for information regarding dealing with heat stress over the past seven days from fellow cattlemen and blog followers.  In addition, I spent the latter part of the week and the weekend trying to effectively care for newly received fall calves experiencing severe heat stress due to grazing toxic fescue grass prior to shipment off of the ranch to my feed yard.

The threat of heat stress to animals is very real and, while it cannot be truly abated by anything other than a reprieve from Mother Nature, there are things that we can do as animal caregivers to help our cattle to more effectively deal with it.  Below is a list of facts that every cattlemen should know about cattle and their tolerance to heat.  The information comes from Dr. Dee Griffin and Dr. Terry Madar.

  • 55 degrees is “short sleeve” weather for cattle — 82 degrees is upper critical temperature.
  • It takes a calf 30 days to acclimate to warm temperatures (approximately 1 degree per day).
  • Heifers are more susceptible to heat than steers due to natural female cycling.
  • Air flow and wind are critical as they decrease the heat index temperatures according to wind speed ( 1 degree = 1 MPH drop in index temperature).
  • Humidity exacerbates heat stress:  cattle are much more comfortable in dry heat.
  • Black hided cattle are more susceptible to heat stress than lighter colored animals as their internal temperature will be 1-1.5 degrees higher.
  • High performing animals often have a faster metabolism and as a result can be affected the most by heat.
  • Stable flies (and other flies and gnats) increase total stress on animals so it is important to maintain the farm to limit insect pests.
  • Water requirements of cattle increase from 10% to 20% per hundred weight of body weight during times of heat stress.  An ample source of cool and clean water provides your best mitigator against heat stress.
  • Hot days combined with nights where the temperature does not fall below 70 degrees are the most problematic, especially if humidity is significant and wind speed is low.
  • There is a two hour lag between the highest heat of the day and when a calf has the highest level of heat stress — after the peak, it takes approximately 6 hours for the calf to cool down.

Below are a list of practices that I employ on my farm to help my animals get through the heat of the summer:

  • I manage the business part of the feed yard such that the majority of our larger animals ship to harvest prior to the high onset of heat in July and early August.
  • I reduce the total number of head of cattle in each pen so that there is more room for air flow across the pen as well as more access to the cool water that the water tank provides for drinking.
  • I maintain my pens such that tall mounds allow for cattle to better take advantage of wind speed.
  • I move in portable shades to the pens of cattle closest to harvest dates, as well as cattle that are more susceptible to heat stress as a result of another challenge (like toxicity from fescue grass on the ranch prior to shipment to the feed yard).
  • Any cattle handling (acclimating, processing or shipping) occurs during the early morning hours during cooler temperatures.
  • Breakfast is delivered early (between 6-8:00am) so that all cattle can eat prior to the onset of heat.  We feed “linner” (my girls’ expression for the combination of lunch and dinner) later in the afternoon so that cattle can eat again at night.
  • Our daily cattle health check is performed early in the morning prior to the onset of heat so that if an animal requires individual attention, it can be provided during the cooler hours of the day.
  • I feed MGA to heifers in the feed yard to prevent the natural female cycling that raises her internal body temperature.
  • My crew and I take special care to not “over feed” our animals during times of heat stress.  Careful feed bunk management is critical to animal health and comfort — especially in the hot summer months.

MegShade1.jpgAs mentioned above, ample cool drinking water (in Nebraska our water comes out of the Ogallala Aquifer in the summer at a temperature of 58 degrees which gives our animals a nice cool drink) and access to air flow (wind) are the two most critical components for alleviating severe heat stress.

It takes a “team effort” to help our cattle, and I am proud of my crew’s dedication to caring.  I am also thankful to have a team of dedicated veterinarians and nutritionists to help us make the best decisions for our animals.

 

10 Comments

Filed under Animal Welfare, General

10 responses to “Managing Heat Stress…

  1. James Ingram

    A perfect example of your awareness, thoughtfulness, consideration and professionalism, Ann. Having worked for the guys in BB for three years and becoming aware of their detailed operations (and similar consideration), I love the level of detail in this post. So informative! (Jim)

  2. Jim and Carol Ingram

    Please explain (with photos) “portable shade” — our ducks and some of our garden plants have too little shade, and I’m looking for ideas on something that won’t flap in the breeze (scaring the ducks) or blow away and is easy to move. No doubt on a smaller scale than yours! Thanks in advance! (Jim)

    • Hi Jim, glad that you enjoyed the post! The base of our shades are recycled tractor tires filled with concrete. They have “umbrella” arms that are made from steel pipe that look similar to a tree with large branches. You attach the mesh tarp to the umbrella arms to get the shade. They are portable and can be picked up and moved with a payloader. I would think that you could make a smaller variation with a regular tire filled with concrete and then smaller (lighter) pipe welded together to get your “branches”. The most expensive part of the shade is the tarp. I will try to send you some more pictures.

      I hope that all is well!
      Anne

      • Jim and Carol Ingram

        Now that you described it, I see that’s what you’re sitting on/under in that last photo. (No other photos are necessary.) All is indeed well with us, other than no longer being bright enough to pick up on the obvious… (Jim)

      • Jim and Carol Ingram

        The eyes are going too… I see now (when I blow it up) that’s Megan, not you. Oh, well. Take it as a compliment that you look as young as your daughters, at least from a distance. (Jim again)

      • You make me laugh, Jim — love your sense of humor! Yes, you are correct that it is Megan under the shade. Thank you for the smile and good luck making your shade. Send me a picture when you are finished🙂

        Anne

  3. theranchwifechronicles

    Anne,
    Good Luck caring for your cattle during Nebraska’s summer heat and humidity. I know it can be miserable.

    The information you shared from Dr. Dee Griffin and Dr. Terry Madar was very interesting. There are several facts I didn’t know.

    One question: Water requirements of cattle increase from 10% to 20% of body weight. On a 1,000 lb animal that is 200. Is that 200 lbs of water or 200 gallons? That would be a lot of gallons of water.

    Keep Cool
    Robyn

    • Fortunately, we have not been very humid and mostly have a nice breeze at our farm. The Eastern half of Nebraska has had a tougher time with increased humidity. This time of year I am always glad that I live in the western half of Nebraska! The dryer heat is a bit easier to deal with. The humidity that we have is nothing compared to the humidity in Florida that I grew up with🙂

      A 1000# animal will have water needs that go from 10 gallons in the cooler temperatures to 20 gallons in the hotter temperatures. I made a typo and it should have been “10% to 20% per hundred weight of the animal.” I will change it!

      I hope that you are doing well,
      Anne

  4. Great read and thanks for the awareness. One thing not mentioned, that may help during those hot humid days when the temperature doesn’t drop at night, consider feeding an electrolyte that is designed for heat stress and mature ruminants. When cattle are under heat stress they lose a lot of potassium and sodium chloride. Cattle will crave potassium when under heat stress. A heat stress electrolyte, is like Gatorade for cattle. Like a marathon runner, it is important to hydrate before the race, during the race and after the race. Same with cattle trying to cope with a hot spell. Pre-hydrate a couple of days before the on set of a hot streak, during the hot streak and 3 to 4 days after. I think you will see, cattle will do less slug feeding, and recover quicker from a hot spell. If putting an electrolyte in feed, its best to do this in the evening TMR so they have the opportunity to get the best absorption rates and retention rates in the cell walls for hydration.. This is also a great way to help bunk break calves coming into a lot during warmer temps. Putting an electrolyte in the water will help get them hydrated quicker and on feed faster.
    The new research out indicates that heat stress starts now at lower temps. and as humidity starts to increase..

  5. Pingback: Raising Food Builds Character… | Feed Yard Foodie

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