Victor Shelton is a retired Agronomist/Grazing Specialist with the Natural Resources Conservation Service (NRCS). He continues to write Grazing Bites in his spare time from his property in southwest Indiana.
Livestock Weather Hazard Guide; Samuel Roberts Noble Foundation, Inc.
I’m writing this during the last part of August and during an absolute dog day of summer. Dog days of summer signifies very hot, sultry days. I’m really not sure that it has anything to do with dogs except they do tend to be less active and seek the coolest place they can find on such a day – I probably should have done more of the same.
On such dog days, shade does become a lot more valuable. If the shady area is big enough, it is almost always at least ten degrees cooler with shade than without.
Humidity is what really makes it miserable. Now, don’t get me wrong, hot is hot, but humid hot, well, it’s just downright miserable and sometimes barely fit for man or beast!
Sometime in the late 70’s, the term “heat index” was first utilized. It was supposed to indicate the “real feel” for temperatures of 80°F or higher, and relative humidity of 40% or more. I don’t know about you, but hot didn’t seem that hot until they created this new term!
The Samuel Roberts Noble Foundation has done some work on hazardous heat and humidity for livestock. That data has been updated at least once. The latest chart can be found at Heat Stress In Cattle: When It's Hot It's Hot and When It's Not, It's Still Hot! – Noble Research Institute.
In the Midwest, the average humidity in the morning around 5AM is about 80% and about 55-60% in the afternoon at about 4PM. Certainly, there is some fluctuation but to keep it simple, as the temperature goes up, the worse it feels even at the same humidity it was when it was cooler. After a rain, there is more moisture in the air, so it usually feels even muggier than average.
There has been a lot of discussion by people about whether shade is needed or not for grazing livestock. When livestock are not provided adequate shade, heat distress occurs and one of the first things noticed is intake of feed/forage is reduced, slowing or stopping rate of gain with the possibility of weight loss.
The preferred temperature range for cattle (polled cattle), in which they do not need to expend energy to keep their body temperature stable, is about 41°F to 77°F. When the temperature is above 77°F, especially with high humidity, cattle can have heat stress, particularly if nighttime temperatures stay over 70˚F. This is especially true if nighttime temperatures are not at least ten degrees cooler than daytime temperatures.
Quite often, early September is still as hot as August, but hopefully not this year. The best thing you can do for grazing livestock is to have paddocks with some shade available, especially in the afternoon and early evening. If that prime space is limited, you may need to move them to paddocks with no shade late evening and then move them to shade late morning to stretch out grazing in areas with shade. Certainly, there is almost always some shade available on the east and north sides of wooded areas. Take advantage of those sites and if shade is very limited, then consider possibly planting some rows or blocks of trees for future shade or invest in some type of portable shade contraption.
Most of Indiana is out of this year’s drought at the moment. Though hay yields have not been good this year for most producers, the last big break in weather found the countryside with lots of freshly mown hay fields and sufficient time to get some dry hay baled up.
It is always a good feeling to reach your comfort zone of stored forage for winter use. Until that time occurs, there seems to be a little added stress and uncertainty. How much is desired beyond that level is somewhat dependent on the individual, but certainly a little bit of extra is never a bad thing because we don’t know what the upcoming winter will be like or how long the livestock may need supplemental forage. I highly recommend doing some figuring to make sure that you have enough and then adjusting as needed or as required to keep you in your comfort zone or close to it.
I am an advocate of extending the grazing season and keeping the livestock grazing as long as sufficient cover is maintained and not overgrazed. When soil moisture is fair to good, the opportunity to grow more forage, especially during the last growth curve bump in the early fall, is very good.
Any fields or paddocks that can be deferred starting in early September and allowed to grow can provide a lot of forage for late fall or winter grazing.
Tall fescue stockpiles better than about any other forage. In fact, winter stockpiling of tall fescue is probably one of its more worthwhile uses! Most tall fescue remains standing well even under the weight of snow cover and also maintains its nutritional value better than other forages. Now, understand, I’m talking fall regrowth now, not left over summer growth for the best value, but even summer growth mixed with some fall regrowth is not too bad once it has been frosted a few times.
How do you really get the most out of your stockpiled pasture?
- Graze/mow/hay the field if needed to even out the stand.
- Apply 30-60 pounds of nitrogen in August to early September; I prefer Urea.
- Defer grazing (stockpile) at least one acre of fescue per 1000-pound live weight.
- Let it grow and rotate through the rest of the paddocks or other areas as long as possible.
- Start strip-grazing stockpiled forage, allocating half to three days’ worth of forage at a time. We’ll talk more about strip grazing in future articles.
If you have not done so already, now is a good time to get feeding areas ready for winter use while the weather and soil conditions are good for cleaning up and applying that material in areas where it is needed. The grazing areas farthest from water and feeding areas and thin soiled slopes are almost always a good choice for application and can use the extra nutrients and organic matter.
Remember, it’s not about maximizing a grazing event, but maximizing a grazing season! Keep on grazing!