Heat stress can be a costly problem in many ways for beef cow/calf producers. It’s something that occurs almost every year, and we often hear about and see the tragic stories of deaths in feedlot or dairy cattle during a serious heat event, resulting in heavy financial losses as well. While economic losses in a cow-calf operation may not look tragic or take place during a single catastrophic event, they can still be significant. The impact of heat stress usually shows up in more subtle ways, including decreases in reproductive efficiency, weaning weight and health.
Heat stress gets more attention in the dog days of summer — especially in the Southern and Eastern regions of the U.S., where “hot days and higher humidity” are more common, and where fescue grazing is more prevalent. Fescue toxicosis can be caused by ergot alkaloids that manifest in fescue grasses. These toxins lead to the vasoconstriction of blood vessels, which interferes with heat dissipation in cattle and can also affect the hormonal response involved in thermoregulation. Heat stress can and does occur in all regions of the U.S. — even in the Northern Plains and into Canada.
Initial and abrupt heat events can be more stressful for animals, as it can take them several days to acclimate to warmer temperatures. We humans can relate to this. For instance, I was in Southern Colorado during an unusual warm spell in late March. At 85ºF, it felt hot and uncomfortable to me. But as I chatted with some people that day about the warmth, we all admitted that 85ºF wouldn’t feel as hot in late July as it did in late March.
One symptom of heat stress in cattle is eating less feed in favor of seeking shade instead or because of erratic feeding patterns, leading to less energy consumption. Cattle, like all mammals, maintain homeostasis in their body temperature through thermoregulation. Previous CRYSTALYX® blogs (linked at the end of this blog) about heat stress have reviewed the thermoregulation process in detail. For cattle, combatting heat stress involves an increase in the respiration rate and heart rate, as well as panting — all of which require more metabolic energy. Couple this increase in energy demand with less grazing, and feed intake levels and the overall energy balance can become compromised. This, in turn, can result in lower production efficiency, as mentioned earlier.
The timing of a heat stress event is very important. While there’s never a good time for heat stress to occur, there can be “worse” times. When heat stress coincides with conception in a cow, for example, the survival of the embryo over the first two to three weeks of gestation can be at risk, as the cow’s hormonal response and energy balance can affect embryonic survival. Additionally, reduced feed intakes lead to a negative energy balance, which increases the risk of embryonic death loss. When this occurs, the estrus cycle needs to reset, and the affected cow either ends up not getting bred again or she breeds late — usually a month or two later, assuming she’s still exposed to bulls.
Bulls’ reproductive performance can also be greatly impacted by heat stress through decreases in semen quality and libido — and the longer they are exposed to heat stress, the greater the negative effect it has. An older but good study from the mid-1980s (Meyerhoeffer et al.) measured semen motility in heat-stressed bulls over an 8-week period. Their semen motility steadily decreased from more than 80% to less than 50% during the 8-week period, and it took almost another 8 weeks for the bulls to return to their pre-heat-stress levels during the recovery period. In mid- to late-spring calving herds, a certain degree of heat stress in bulls during the breeding season is unavoidable, making heat stress mitigation equally if not more important for bulls than for cows.
How and where can CRYSTALYX® help?
CRYSTALYX® offers several supplement options that, along with good animal husbandry practices, can help combat and mitigate the negative impacts of heat stress. Offering feed-through fly control is a particularly good practice for combatting heat stress, as a heavy fly infestation only adds insult to injury during periods of heat stress. Groupings of animals fighting flies further negatively affect grazing patterns and feed intakes.
Several CRYSTALYX® supplement options deliver ClariFly® and Altosid®, which can help reduce overall fly populations. Over the past couple years, we’ve seen great success with our CRYSTALYX® Blueprint® Shade mineral offerings, which are available both with and without ClariFly®. Our Shade solutions also contain capsicum, an essential oil that promotes the vasodilation of blood vessels to aid in the thermoregulation process.
I mentioned fescue grazing earlier, and heat stress is bad enough without the negative impact of fescue toxicosis. CRYSTALYX Blueprint Fescue Phos Mineral with FEB-200 and ClariFly is a premium-quality mineral. Along with ClariFly for fly control, this option contains FEB-200 to support overall performance and help cattle meet their maximum genetic potential on fescue forages.
Whatever your summer grazing program may look like, you can feel confident that our Crystalyx solutions supplement optimal levels of minerals and vitamins for your herd while also providing heat abatement and fly control, all in one convenient and reliable formula. Please check out some past blog posts from our CRYSTALYX® team on heat stress — and stay cool this summer!
Beat the heat and flies with the following CRYSTALYX® options
https://www.crystalyx.com/blog/goodbye-winter-hello-heat-stress-tips-on-keeping-cattle-comfortable/
https://www.crystalyx.com/blog/get-out-of-the-heat-and-into-the-shade/
https://www.crystalyx.com/blog/beat-the-summer-heat-with-blueprint-shade/
Meyerhoeffer, D.C., R.P. Wettemann, S.W. Coleman and M.E. Wells. 1985. Reproductive criteria of beef bulls during and after exposure to increased ambient temperature. J. Anim. Sci. 60:352-357.
