Lessons Learned from Heat Stress

Posted: June 22, 2016 | Written By: Heidi Doering-Resch, M.S. Form-A-Feed Beef Technical Services and Allison VanDerWal, Form-A-Feed Summer Beef Intern

beef cattle

Summer is officially here whether we are ready or not. Last weekend’s heat wave was a reminder to many producers how tough summer heat and humidity can be on cattle. We hope you made it through relatively unscathed, but also wanted to take this moment to remind you of some items to consider when it comes to dealing with heat stress.

Hydro-Lac heat stress app and monitoring the weather:

Have you registered for the Hydro-Lac Heat Stress App? We hope you have and that you are actively using this tool for updates on when these heat events are going to occur, how Hydro-Lac can help you preserve both intakes and gain during this stressful time, and how much Hydro-Lac to feed based on your feedlot risk assessment snapshot. Haven’t done this yet? Go to Form-A-Feed’s resource web page and click the big red button that says ‘Sign up today’!

As producers and crop farmers, one of our favorite topics of conversation is the weather.  Between monitoring the forecast daily and knowing what the weather is capable of in these summer months, we are able to prepare for a heat stress event prior to the day of. July through mid-August is when there is the greatest probability of a heat stress event occurring. However, like this past week, we know it is still possible to occur before or after that range. As a general rule of thumb, if the forecast is predicting temperatures hotter than normal it is a general sign that producers should begin their heat stress plan.

Heifers vs. steers:

We know that colored cattle are more susceptible to heat stress than dairy steers; the thicker hide and darker hair allows them to retain heat more than a thin hided dairy steer. However, there is also a difference in heat stress between heifers and steers. In a recent study conducted in Texas on heat stress, 3.2% of deaths were heifers and 2.9% were steers. How can we help alleviate this issue? We recommend feeding Hydro-Lac and MGA (Beef Pack MGA) to heifers to help lessen heat stress by decreasing socialization via altering their estrus cycle.

Pen direction and pen space:

When analyzing pen situations and deaths, almost half (47.1%) of the heat stress feedlot deaths occurred in lots that faced south and west. This study also found that by increasing pen space, via decreasing the number of animals per pen, there was a corresponding decrease in deaths per pen.

High-risk cattle:

It is also important to remember that some types of cattle are more at risk than others. Yes, fleshier cattle have more body fat and can be more prone, but we also need to take into consideration sick and naïve, or newly arrived cattle. Sick animals’ immune systems are compromised and usually running a fever which will make it harder for them to handle the stress of severe heat and humidity. Our sick pens also tend to house respiratory issues which will bring struggle the hotter and more humid it is. Naive cattle are also high-risk cattle. It is easy to give these cattle less attention during a heat event because they are lighter weight cattle. However, these cattle have usually experienced the stress of shipping, are already dehydrated, and are possibly weaning which makes them more susceptible to illness and severe heat stress.

Cooling pointers:

During a heat stress event it is important to do all you can to help keep cattle cool and reduce as much production loss as possible. First off, be prepared for the heat event PRIOR to the day it arrives. Proactive planning will help you lose less performance. Fans should be added to facilities to aid in adequate airflow.  Be sure you have enough airflow in the pens so cattle do not bunch and that air is pushed off their backs to help dissipate heat.

Installing a sprinkler system is also beneficial in cooling cattle. If a sprinkler system is in place at your facility, it is important to start earlier in the morning so cattle are not shocked or cooled off too rapidly. It has been found that large droplets of water sprayed in 5 to 10 minute increments once or twice an hour is more beneficial than a constant mist. This is because cattle cool off more efficiently when the hide is wet. This can be achieved by a large droplet spray instead of a mist that just wets the hair.  In open lots, mound wetting helps enable body heat to be dissipated to the cooler damp surface and off the cattle. Be sure you wet the top of the mound so airflow is at its greatest.

Many producers also rely on cattle cooling down at night to help with daytime heat stress, however sometimes we just do not get nighttime temperatures back under 75 degrees F. A temperature humidity index or an early morning dew point temperature above 70 is indication that it did not cool down enough that night. It is these next days after no nighttime cooling that animals will be at their highest risk for heat stress.

Post heat event:

It is not unusual for cattle to go off feed in severe heat if proper cooling procedures are not in place. Excessive panting can cause the saliva that would normally buffer the rumen to drop to the ground. This alters the rumen pH, causing discomfort to cattle. Ever wonder why we have more acidosis in the summer months? Digestion also gives off a lot of heat, especially with high forage diets, which can turn cattle away from the bunk. Because of these factors we need to be careful when we bring cattle back up on feed. It is important to check bunks diligently during heat stress. If cattle do go off feed, you must ensure the TMR in the bunk is cool and fresh or you are just adding to the problem by supplying heated, yeast-growing feedstuffs to an already compromised rumen environment. Yes, that means scooping bunks, which I know, is everyone’s favorite job.

We can never be too cautious when it comes to heat stress in cattle.  Efficiency of cattle production can be greatly affected during a heat event and being aware of the effects and how we can minimize them can be a very useful tool when feeding cattle through the summer months. Be sure to ask your Form-A-Feed representative about heat stress practices or products that may be beneficial to your operation!

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