Cattle Management During the Heat of Summer – Some Considerations
- Louisiana GLCI
- Jul 7
- 3 min read
Updated: Aug 13
Natural shade is always better than a barn or shed. It is typically 10-15 degrees cooler than artificial shade. Plenty of clean, fresh water is also needed to reduce heat stress. Pasture design or layout is critical to allow for adequate natural shade in each pasture. Open shade structures are second best.
Cool water (piped, well or groundwater), is typically 30 degrees below body temp. Shade over water troughs is not a bad idea. Smaller water troughs with a good supply and full flow floats, valves, and pipes, as not to restrict flow, are also a good idea to use.
Surface water from ponds and other perennial bodies of water is usually close to the same temperature as the ambient air temperature. Also, sediment, animal waste, other contaminants from runoff, can severely degrade the quality of surface water.
The thermo-neutral zone for beef cattle is 32 to 77 degrees. This is the range in temperatures at which cattle are comfortable and are not stressed by either heat or cold. Lack of nighttime cooling in Louisiana is usually what causes heat stress during the summer.
Cattle can tolerate high daytime temperatures, as long as nighttime temperatures are low enough to allow cooling of the body temperature back to normal, each night or early morning. This must occur before the next daytime heating cycle begins, which is usually about a half hour before sunrise. If normal body temperature cannot be reached, each night or early morning, heat stress begins to occur. Movement is decreased and organs begin to lose function.
If conditions such as cloudy days, rain events, winds, and lower humidities do not occur, with regularity, loss of productivity, sickness, and death will occur. The Temperature Humidity Index, which takes into consideration the humidity level and wind, often elevates the actual temperature feel, by adding 10-15 degrees during times of high humidity. Typically, almost every night in Louisiana, from May through October, has a temperature of 78+ degrees and 95-100% relative humidity! It gets worse as one goes further south, in Louisiana.
Good nutrition from an ample supply of fresh tender, grazed forage, is best. If supplementing, stay away from starch (corn or other grain) based feeds. These supplements will cause drop in the rumen pH, acidosis, and a severe disruption in the pasture cattle's digestive system. Additional disruptions will add to problems with heat stress. Supplement with stored forage and a high protein, low starch, supplement, such as DDG, corn gluten, soybean meal, whole cottonseed, high protein cubes, etc. It’s also important to provide a steady supply of good quality (digestible) vitamins, minerals, and salt.
Long term, the correct breed, or breed combinations, for your spot on the Earth, is critically important. Most cattle can withstand high daytime temperatures, as long as there is nighttime cooling, every night. Fat cattle that lack thin, porous skin, and have a limited ability to sweat, are most at risk. Heat dissipation is difficult when exterior fat layers, between the muscle and skin, serve as insulation, which blocks dissipation of heat. Cross-bred cattle also possess hybrid vigor or heterosis, that gives them hardiness, and resistance to sickness and environmental stress. Certain breed crosses can add extraordinary amounts of heat tolerance. Thinner, porous skin, the ability to sweat, internal fat deposition patterns during warm weather, and reduced energy requirements, are characteristics of breed crosses that make cattle more suitable for Louisiana’s harsh warm seasons.
Down here in the deep south, during the warm seasons, lack of nighttime cooling is usually the problem. Concerns with near 80 degree nights and 90-100% humidity, just about every night, from now until October, are legitimate! Good luck.
Stuart Gardner – Area Range Conservationist
USDA Natural Resources Conservation Service, Lafayette, Louisiana
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