Seasonal changes and unpredictable weather cannot be avoided when it comes to beef cattle production \u2013 but they can be anticipated and managed effectively. Heading into warmer months, heat stress in beef cattle becomes a major concern for many cow\/calf producers and feedyard operators. Understanding the biological impact of heat stress, knowing how to spot it and taking preventative action are all ways to protect animal wellbeing and profitability. <\/p>\n\n\n\n
As a rule of thumb, if the Temperature Humidity Index (THI) is above 80, beef cattle are likely to experience heat stress. However, the likelihood of heat stress can change with weather events like precipitation or temperature variation such as warm nights. Almost all outdoor environments can be conducive to heat stress at some point during the year. <\/p>\n\n\n\n
Signs of heat stress in cattle: <\/p>\n\n\n\n
Upon the onset of heat stress, cattle experience a decrease in dry matter intake, which has been hypothesized as a method to help reduce metabolic heat. Changes in blood flow, oxygen and energy availability are also taking place inside the animal. Together, these biological reactions lead to a decline in health and performance. <\/p>\n\n\n\n
When cattle are under heat stress, blood flow is diverted from visceral tissue \u2014 which lines the blood vessels, stomach, digestive tract and other internal organs \u2014 to the skin, which allows for heat dissipation. This reduction in blood flow makes oxygen, energy and other nutrients less available to the epithelial layer of cells lining the intestinal tract. The tight junctions that hold the intestinal tract\u2019s epithelial cells together weaken, allowing pathogens and toxins to more easily enter the bloodstream, leading to a condition called leaky gut. <\/p>\n\n\n\n
Heat-stress induced leaky gut can take a large toll on an animal\u2019s health and immunity. Once the bacteria, pathogens or their toxins pass between cells, the immune system recognizes them and triggers an immune response to destroy and remove the invaders. This inflammatory process requires significant amounts of already limited nutrients and pulls them away from other key functions like muscle growth and reproduction. <\/p>\n\n\n\n
This chronic inflammation can also have a negative impact on hoof health by causing a reduction in hoof horn tissue production. This leads to the formation of lower-quality hoof horn tissue and can eventually lead to lameness. During these periods of heat stress, cattle will also spend more time standing to dissipate heat \u2013 increased standing time can add to hoof health concerns. <\/p>\n\n\n\n
While heat stress may be unavoidable, there is a way to take preventative action and prepare animals to better cope when warmer temperatures hit. Zinc plays a key role in maintaining epithelial integrity and strengthening tight junctions. Feeding Zinpro\u00ae Availa\u00ae Zn<\/a> \u2014 the most bioavailable form of zinc available on the market \u2013 can make cattle more effective at reducing leaky gut on pasture and in the feedlot. <\/p>\n\n\n\n When evaluated in heat-stressed cattle, feeding Zinpro Availa Zn proved to be effective in reducing leaky gut. Animals supplemented with zinc sulfate had a reduction in feed intake of 22.8% compared to only a 14.9% reduction in feed intake for steers fed Zinpro Availa Zn. Additionally, animals receiving Zinpro had lower rectal temperatures, indicating less inflammation after sustaining a period of heat stress. <\/p>\n\n\n\n Feeding Zinpro Availa Zn also had a positive impact on gut morphology with greater intestinal villi height and decreased villi width occurring in heat stressed and non-heat stressed cattle. Stronger gut morphology is important to maintain tight junctions and reduce intestinal permeability that leads to leaky gut. <\/p>\n\n\n\nHeat Stress Management Strategies<\/strong><\/h2>\n\n\n\n