Dale Blasi, stocker, forages, nutrition and management specialist & AJ Tarpoff, DVM, extension veterinarian
Heat stress events across the Central Plains region can be devastating to finishing beef cattle. The use of shade has been evaluated as a mitigation strategy to improve animal comfort and growth performance, with very positive outcomes for the feed yard sector. However, limited information on animal comfort and growth performance for growing cattle when shade is provided is available. To address this lack of information, two growing studies involving 852 head of heifers (553+62 lb) were conducted during the summers of 2021 and 2022 to evaluate the impacts of limit feeding and shade access as possible strategies to improve cattle efficiency, reduce water usage, and improve animal comfort in growing cattle. Only the main effects of shade allocation will be discussed within this article for brevity. Readers are welcome to review the full article at https://newprairiepress.org/kaesrr/vol9/iss1/3/
Before cattle arrival, two shade structures (40 × 40 ft) per block were randomly assigned to cover two pens per structure; for the two pens under a common shade structure, one pen was fed each of the two dietary treatments. Shade structures provided 77 ± 6.3 ft2 of shade per animal (Strobel Manufacturing Inc., Clarks, NE).
To determine the effects of shade on animal comfort, animals were evaluated at 9:30 a.m., 1:30 p.m., and 5:30 p.m. on days when the temperature humidity index (THI) was estimated to be greater than 74 (US MARC Animal Comfort Index). Using a method adapted from Guaghan et al. (2008) individual panting score was determined using respiration rate and breathing conditions. Three animals per pen were selected randomly at each time point to represent each pen. The three values were averaged to obtain a mean panting score for each pen. Water usage was measured via iPERL water meters (SENSUS, Morrisville, NC) connected to individual automatic waterers (Lil’ Spring 3000; Miraco Livestock Water Systems, Grinnell, IA) for each pen. The presented water usage and panting scores are only from year one.
Heifers provided with shade had heavier day 90 and day 97 body weights than those without shade access. Average daily gains from day 0 to 97 were greater for shaded heifers compared with non-shaded heifers. Calves fed for ad libitum intake in shaded pens had greater dry matter feed intake than calves in non-shaded pens fed for ad libitum intake, whereas limit-fed calves in non-shaded pens and shaded pens did not differ in DM intake. Gain-to-feed was better for calves in shaded pens than in non-shaded pens.
Calves in non-shaded pens had greater average panting scores than calves in shaded pens. We attribute this difference to increased animal comfort due to reduced solar radiation exposure in shaded pens, leading to lower heat load during the summer. Water usage was 11% less for shaded calves than for non-shaded calves. This can be attributed to a decrease in heat load of calves in shaded pens compared with calves in non-shaded pens.
In summary, the results of this study demonstrate that during periods of heat stress, the provision of shade improves average daily gain by 7%, increases feed intake by 6%, improves feed efficiency by 4%, and improves cattle comfort (measured by panting scores), as well as reducing water usage (consumption) by 11%.