Modern homes and workplaces are mostly air-conditioned and so working humans are quite literally not getting so hot and bothered over the stresses brought on by the highest seasonal temperatures.  Having said that, on dairy operations, there are still many opportunities to join the animals we care for in panting and sweating and sometimes getting seriously ill due to rising temperatures. Today we are going to look at some Keep It Simple ways that we can deal with heat stress on the modern dairy operation.  Are you still using the same heat stress strategies that were used by the generation ahead of you?  If so, you may not only be closer to losing your cool but, also, closer to losing your cattle too! Keeping it Simple DOES NOT mean Keeping it the Same!

When it comes to heat stress every degree adds up. The following ideas could provide you with 12 degrees of separation from ineffective methods of dairy heat stress management!

  1. HEAT STRESS: Ignoring Heat Stress COULD BE FATAL
    First off you must accept that there isn’t a choice when it comes to dealing with heat stress. You must keep your cows cool.  Nothing gets done without them. Every year heat stress accounts for losses to the tune of US$1.7 billion. One very serious and costly consequence is lowered reproduction. (Read more: BEAT THE HEAT – DAIRY CATTLE BREEDING AND MILK PRODUCTION CHALLENGES CAUSED BY HEAT STRESS and 10 WAYS COOL CALVES BEAT THE HEAT) When temperatures rise, so should your skill in managing the impact on your dairy herd. Some management priorities are optional but ignoring heat stress could be fatal.
    It is easy to recognize as you walk past panting cows that, not only are they picking up heat from the overheated environment, but they are also generating a substantial amount of heat themselves.  It’s a vicious cycle.  Although heat happens everywhere, you may think that, if you’re not in a hot spot, heat stress won’t affect your operation.  Granted some, like California, have severe stress especially during exceptionally high temp days but, to some extent, cattle have adapted to what is the norm in these locations.  Stress occurs in cattle when they have sudden changes in temperature. Recently we had three days of normal (aka comfortable) weather that was followed by a 10-degree spike. Dairy cows are forced to adapt to these sudden changes, regardless of location, and that makes them candidates for heat stress.  Up and down are BOTH stressors. Remember when you got sun stroke at the family reunion?  How long did it take you to get back to your normal self?
    It’s always tempting to use what works on us to solve problems faced by our cattle. That could lead you to suppose that shaded structures and wooded groves are two of the best measures you need to put in place to combat summer cattle heat stress. Your reasoning concludes that summer milk gets made in the shade – so provide lots of shade. Basically, money grows on (shady) trees. Unfortunately, panting, increased water intake and decreased feed intake are the all too familiar visible signs of heat stress that even dairy cattle in shady conditions experience. As well as the obvious visible signs there are invisible signs of heat stress that are also being expressed through rumen acidosis, decreased reproductive performance and increased susceptibility to metabolic diseases.
    Responsible managers can’t stop with cooling interventions such as shade, fans and sprinklers. How are they working for you?  Do you still have substantial decreases in performance? Have you decreased feed intake to lower the heat generated by rumination?  No doubt, it is frustrating. You may think you’re winning that battle but you are losing the production war at the same time.  Decreased feed intake means lost milk.  Increased feed intake means poor performance due to heat stress.  It’s a hot mess no matter how you look at it.
  5. HEAT STRESS: COLD WATER CHILL is Just a DROP in the BUCKET that doesn’t LAST
    Effectively changing the hot mass of a dairy cow’s rumen to a cooler state is easier said than done.  Using human experience, we want to transfer our success with drinking chilled beverages to our overheated cattle. Studies have been undertaken to determine if chilled water could be a solution for heat-stressed animals.  Unfortunately, the results conclude that chilled water is only about 32% effective in lowering body temperature.  Furthermore, the cooling effect only last two hours or less.  This is not enough to keep cows’ body temperatures from rising above the critical temperature of thermoneutrality.  The thermo-neutral zone of dairy cows ranges from just above zero to 22ºC. Above this critical temperature (combined with humidity) cows begin to alter their basal metabolism and metabolic rate. Nevertheless, chilled water may remain as a part of your larger plan or may be used as an incentive for cows to enter the milking parlor.
  6. HEAT STRESS: A Cold Fact that Brings Hope to Heat Stress.
    As mentioned earlier (3), reducing the thermoregulation response by decreasing digestion also decreases milk production. That’s the bad news. If we are going to get a serious handle on managing heat stress, we have to get ourselves out of this vicious cycle. The good news is that recent findings from heat stress studies on dairy cow performance have shown that reduction in feed intake plays a much smaller role than previously thought. Smaller role. Bigger hope.
    The physiology underlying heat stress and abatement methods has been studied for decades. Scientists at Iowa State have run trials that concluded that, “reduction in feed intake accounts for only 35-50% of the decrease in milk production”.  The other 45 to 50% is due to other causes. More research is needed to focus on these remaining issues which could optimise animal feeding and heat management during heat stress. It would be great if simply targeting the correct research was that easy.  However, if abatement strategies are somewhat successful, they will be skewing the results which will then underestimate the problems. Is heat stress under control or under-controlled?  Each dairy operation needs to answer that question with their own assessment of causes, effects and results.
    You never know where you will discover a new approach to bovine health management. Some suggestions we recognize and accept because of parallels in human health.  One such recent finding is the role of insulin in relation to dairy cattle susceptibility and rates of survival when exposed to heat stress.  Consult with your nutritionist for strategies to improve insulin activity in lactating cows. This could improve their ability to cope with heat stress.
    It has taken eight steps to get us to the guts of the matter, as was hinted at in the title of this article. Thank you for persisting this far.  It bodes well for your persistence in seeking heat stress solutions. Here we come to a discussion of another thermoregulation response, namely the shift of blood flow from internal organs to the skin surface.  You will be familiar with the term ‘leaky gut’ which describes the decrease in the health of the gut. When your dairy cows are also suffering from rumen acidosis, they experience a double setback at the gut level.

    1. When gut health is sub-optimal, it impairs the absorption of nutrients that are critical in the rumen for fermentation of feed.
    2. Continued research by Iowa State University also suggests that leaky gut in dairy cows could be a significant factor in other metabolic diseases, including ketosis.
    Dairy managers need to be prepared to take advantage of even the newest feeding technologies. Phytonutrients fall into this category.  They represent a promising natural solution for alleviating heat stress. As reported by Dr. Emma Wall and Jennifer Maurin, Pancosma, Switzerland in “Heat Stress a Refreshing New Take” a specific combination of phytomolecules consisting of capsicum oleoresin, cinnamaldehyde and eugenol (CCE*), does just that.

    1. Capsicum oleoresin has two significant benefits. It increases feeding frequency and does so without increasing total feed intake.  This results in a more consistently filled rumen. It also stabilises heat production and reduces the occurrence of rumen lesions.
    2. The combination of cinnamaldehyde and eugenol acts upon the lower gut. They decrease inflammation and reduce the local generation of heat. This aids in maintaining optimal gut structure and nutrient absorption, while improving the breakdown of ingested feed and enhancing the volatile acids profile and optimal protein metabolism.
      The combination of the two phytonutrients (CCE), has positive effects on both the rumen and lower gut. They prevent any additional heat from being generated and yet optimise digestion and nutrient absorption.
    Seeking ways to manage heat stress in dairy cattle is the same as any other proactive actions in managing a dairy.  Each advance improves outcomes and, at the same time, has the potential to inspire other improvements. Raising awareness through heat wave warnings issued by media channels has proven to result in heat-related mortality (LINK 28). This raises the possibility that adding animal heat advisories would have further positive impacts. More data from more stations could provide even bigger advantages. As data is added and improved, refining it to report exact in-barn heat stress, as opposed to only ambient or outdoor values, is the next level that needs to targeted.
  12. HEAT STRESS: Weather Predictions are NOT PROMISING
    There is an old saying that the only things that are certain are “Death and Taxes”.  Well, dairy farmers need to recognize that climate change is adding a third factor, “Death, Taxes and Heat Stress!”  Regardless of what your viewpoint is on climate change, there is no doubt that we will continue to see a rise in the frequency and severity of extreme weather events such as heat waves. This has the potential for a corresponding rise in the mortality rate of cattle and, therefore, by extension, a rise in economic losses associated with heat stress. We can’t outwait this problem in the hope that it will go away without action on our part.

The Bullvine Bottom Line

Losing your cool means losing your cattle.  If you’re serious about making heat stress management a priority, seek out and put into place feeding rations that improve gut health. The goal here is to improve the performance of your dairy herd through solutions that decrease heat stress induced metabolic disease. Keep an open mind and you could be several degrees closer to effective heat stress management and that’s cool!