by: Dr. Brandi Bourg Karisch
Extension Beef Cattle Specialist Mississippi State University

As we approach the heat of the summer months, many producers are battling the heat and humidity that is an integral part of life in the south. Summer brings with it rising temperatures and typically decreasing animal performance. The heat isn't the only thing to blame for this decline in animal performance. Summer also typically brings a decline in pasture performance as well. This decline applies to not only stocker cattle, but also pre-weaned calves as well.

Hot temperatures have a big impact on cattle intake. Most people also feel the same reduction in the desire to eat during the summer months as well. Who wants to eat a heavy lunch when its 102° F outside? Not me! Cattle experience the same response to heat stress, but don't have access to an air conditioned house to go in to during the heat of the day. Remember for calves to gain more weight they must consume more energy and protein. If their intake is decreased, a corresponding decrease in gain is likely to accompany the decrease in intake.
Spring born calves may see a summer slump in growth related to their dam's lactation curve, along with a decline in the quality and quantity of forage. As a cow gets farther into her lactation curve (and closer to weaning time), the amount of milk she produces declines. Her highest milk production actually occurs when the calf is around two months of age. If drought conditions coincide with this decrease in milk production, it may be a good idea to consider early weaning calves to conserve calf weigh gain as well as cow body condition.
Water is key to managing the heat of the summer! Provide access to clean, fresh water: Water is an essential nutrient, and should be readily accessible. Cattle should always be provided with a source of cool, clean drinking water, but this source becomes even more important during high heat. Be sure there is adequate space and water flow to accommodate the number of head in a pasture or pen. During extreme heat, it may be necessary to add additional water sources to ensure all animals have access. It is also important to check water supplies daily during the summer months since without access to water cattle will quickly succumb to dehydration. Water temperature is also an important consideration. Warmer water may lead to an increase in water requirements needed to regulate the animal's body temperature.
Providing access to adequate shade is extremely important during the summer months. Shade serves to reduce the thermal load, and is particularly important for dark hided cattle. For 400 lb calves it is recommended to provide at least 18 ft2 per head, 25 ft2 per head for 800 lb calves, and 30 to 40 ft2 per head for mature cows. Shade should be at least 10 feet high to ensure adequate air flow. It is also important to monitor conditions under shade structures, if conditions become excessively muddy under shade, it may be a good idea to rotate cattle to a different pasture.
Shade can be provided by natural or artificial means. Shade can be provided by trees, buildings, or portable shade structures.
The term "summer slump" is most often associated with fescue toxicosis, and for producers in the northern part of the state this is definitely a concern. Endophyte infected tall fescue is the concern here. Ergot alkaloids are concentrated in the seed of the plant, and can depress grazing activity and forage intake in cattle on infected pastures, along with exacerbating heat stress. Pastures should be managed through mowing or grazing to reduce seed heads, or the effects of fescue toxicosis can be mitigated through dilution with other grasses or feed sources.
Pasture quality and quantity often slumps in the summer months as well. Often the heat of the summer also brings dry conditions, which slows forage growth, and producers see a decline in forage quantity. As plants become more mature in the summer months, an increase is seen in the indigestible parts of the plant. This means a decrease in nutrient (energy and protein) quality of pastures during the summer months. Even though there may be an abundant amount of forage available, it is likely not providing enough nutrients for calves to continue to grow and gain at desired rates. It may be necessary to provide a supplement to calves on pasture during this time to manage slumps in gain.
Maintaining proper stocking rates is an important part of managing summer slumps. When conditions get hot and dry during the summer months, producers should be especially mindful of not overgrazing pastures. Overgrazing often results from having pastures overstocked, and can have a negative impact on future grazing conditions. Overgrazing not only removes plant material above the ground, it also decreases the roots of the plant. When forages are subjected to drought conditions, having a strong root system is very important. Manage groups of cattle to ensure that pastures are not overstocked.
Reducing the negative impact that the summer months can have on gains is a daunting task, but certainly possible with good management practices. Take into account conditions that may cause stress or reductions in intake, and implement management practices that can reduce these impacts. With a little extra planning, the summer slump can become just a slight bump in the road.
For more information about beef cattle production, contact an office of the Mississippi State University Extension Service, and visit extension.msstate.edu/beef.

Take Steps To Manage Effects Of Summer Heat  http://cattletoday.com/archive/2016/July/CT3342.php


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