You may look at me like I have two heads, but we are entering a time where we need to be aware of early season heat stress in our high production livestock. It seems strange, even to me, to bring this up in mid-March - after all, we didn’t see the sun in all of January and most of February. For the first time in years, we had almost 2 months of snow covered ground and we went several weeks with consecutive temperatures below freezing. In short, I would call this a normal winter. However, it appears that spring has arrived. Many of you may not be quite ready to shed your coats, but we are getting close.
I discussed earlier in the year that cold weather isn’t a big deal for most of our livestock until we start approaching zero, or below. Our ruminant livestock are blessed to have a furnace in their bellies that will generate a lot of heat to keep them warm. As long as they are well fed, we don’t have a lot to worry about. It is hard to imagine that the moderate temperatures we are having now could cause a concern. However, the advantage that rumen fermentation provides in the winter becomes a concern as we move into spring. Also, livestock will develop a thicker hair coat in the winter and it takes a little time for them to slick off in preparation for summer. High energy diets and a thicker hair coat can have your animals panting much earlier than we would think.
The Thermal Heat Index (THI) was originally developed by E.C. Thom in 1959. The index is a scaled system that factors ambient temperature and relative humidity to identify combinations where heat stress behaviors can be observed. The initial threshold is triggered at 70 degrees and 70 percent humidity. Mild heat stress can be reached at 75 degrees and 70 percent humidity. Our current humidity levels are around 85%. Which means that we are hitting the threshold now and some of our higher production animals could be feeling the effects.
Heat stress produces visible behaviors. You could see: Increase breathing rates, panting and open-mouthed breathing, drooling, restlessness, decreased feed consumption, and refusing to lie down. Pastured livestock may be seeking shade and be seen huddling together in areas that they typically find shade once the trees leaf out.
Managing heat stress is a little easier in early spring that later in the summer. Regardless of the time of year, giving your animals access to fresh, clean water is always important. If you have heated waterers, you may want to turn off the heaters but still be aware that the temperature can drop back below freezing. Make sure you are keeping your waterers cleaned as well. This should be a weekly task to prevent feed build-up and algae growth. Our dairy producers should have their fans turned on to keep cool air flowing through the barns. Be watchful not to overcrowd animals in pens for extended periods of time. This is also true of the crowd pen leading to the milk parlor. You may consider reducing the number of cows you bring up at one time or resist the urge to push them up too tight with the crowd gate.
Our winter programming season has come to an end. We will have a variety of programs offered throughout the spring and summer months. Our next formal program will be a small ruminant parasite management workshop and FAMACHA certification program on May 16th. We will also be hosting a couple pasture walk programs, a small grains field day, and a small ruminant field day later this summer. If you are interested in any of these programs, you can check out the events calendar on our website at wayne.osu.edu. Also, Frank and I will begin publishing a quarterly newsletter. I will be emailing this out to our current email list. If you have not been getting email notices from me, or would like to receive a paper copy, contact the OSU Extension office at 330-264-8722.
John Yost is an extension educator IV, Agriculture and Natural Resources, at OSU Extension-Wayne County.
This article was previously published in The Daily Record.