Shade and water misting effects on behavior, physiology, performance, and carcass traits of heat-stressed feedlot cattle.

Abstract

One hundred twelve crossbred feedlot heifers were used in two experiments to assess the impact of heat stress and its relief by shade and(or) water misting on behavior, physiology, performance, and carcass traits. Treatments were 1) no shading or misting (CONT); 2) only misting (MIST); 3) only shading (SHADE); and 4) shading plus misting (SHMI). Head in the feed bunk, head in or above the waterer, walking, standing, and lying behaviors were observed. Rectal temperature, respiration rate, and carcass traits were measured, as well as DMI, ADG, and feed:gain. Dietary NEm and NEg concentrations were calculated from performance data. In Exp. 1, (32 heifers; average BW 288 kg) the CONT heifers spent more time lying down than all others (P < 0.01). In addition, CONT heifers spent less time (P < 0.01) standing than SHADE and MIST heifers. Misting decreased (P < 0.01) rectal temperature and MIST as well as SHADE lowered (P < 0.05) respiration rates. In Exp. 2 (80 heifers; average BW = 336 kg), lying and walking behaviors did not differ among treatments, but shade increased (P < 0.01) standing behavior in heifers. The MIST cattle performed less (P < 0.05) head-above-water behavior than unmisted cattle. Rectal temperatures did not differ among treatments, but respiration rate was lower in shaded than in unshaded heifers (P < 0.05). Shaded compared with unshaded heifers had greater DMI (9.46 vs 8.80 +/- 0.14 kg/d, P < 0.01) and ADG (1.6 vs 1.41 +/- 0.1 kg/d, P < 0.01). Heifers provided with shade reached their target BW 20 d earlier than the unshaded heifers and differed in final BW (547 vs 520 +/- 6 kg, P < 0.01). Feed:gain and calculated NEg and NEm concentrations did not differ among treatments, and carcass traits were generally similar among treatments. In conclusion, cattle without shade had a physiological and behavioral stress response to heat that negatively affected productivity. Providing shade for beef cattle was a suitable solution to decrease heat stress and to lower the negative effects of heat on performance, whereas misting was largely ineffective.

The effect of type of shade on physiology, behaviour and performance of grazing steers

“…Under both types of shade, steers spent more time lying than standing. This observation is consistent with results reported by Muller et al (1994c) and Velazco (2010, 2011) but contrary to other observations (Mitlöhner et al, 2001;Kendall et al, 2006). When increased standing behaviour is observed during summer, it is likely an effort to maximize the animal surface area exposed to the environment to regulate body temperature (Kendall et al, 2006).…”

“…The moderate rate of growth of animals (0.622 kg/a per day) could decrease the sensitivity to heat stress as the comfort line depends on the level of production being more sensitive animals presenting higher level of production as dairy cows and feedlot cattle (Berman, 2005). In addition, the effect of the absence of shade on animal performance can be attributed to acclimatization of unshaded cattle (McDaniel and Roark, 1956;Nienaber and Hahn, 2007;Renaudeau et al, 2010), compensatory growth after periods of heat stress offsetting initial benefits of providing shade (Mader et al, 1999b;Mitlöhner et al, 2001) and/or a sufficient cooling period at night to prevent any further decline in animal production (Igono et al, 1992). In general for temperate climates, animal response varies according to the intensity and duration of the thermal challenge (Renaudeau et al, 2012).…”

Comportamiento de terneras de la raza Holstein alimentadas con silaje pre-secado del pasto Tifton 85 (Cynodon spp.)

“…As bezerras foram suplementadas com farelo de soja (46%), sendo as dietas ajustadas para o ganho médio de 1 kg/dia, além de considerar 10% de sobras. Também foi fornecido 30g de sal mineral (Guabi ® ) por animal, uma vez ao dia, incorporado ao farelo de soja (NRC, 2001 Foi considerada atividade de alimentação quando o animal estava apreendendo o alimento, estando este com a cabeça dentro do cocho (Mitlöhner et al, 2001, Muhammad et al, 2016. Já a ruminação, era a ocorrência de repetidas remastigações dos alimentos, sem apreensão destes.…”

“…Já a ruminação, era a ocorrência de repetidas remastigações dos alimentos, sem apreensão destes. Os animais encontravam-se em ócio (Muhammad et al, 2016), quando estavam parados, em pé (considerado como uma postura ereta inativa, sem nenhuma locomoção) ou deitados (quando o corpo se encontrava em contato com o piso) (Mitlöhner et al, 2001). A atividade dormindo foi considerada quando deitados, com o pescoço virado para o flanco e com os olhos fechados.…”

“…Foram consideradas como outras atividades, quando o animal interagia com o outro, brincavam ou estavam em estado de atenção, exceto quando estavam ruminando ou se alimentando (Miotto et al, 2014). Durante as observações comportamentais, a frequência que urinavam, defecavam e que consumiam água (quando o animal estava com a cabeça sobre ou no bebedouro) (Mitlöhner et al, 2001), também foi registrada quando estas ocorriam ao final do intervalo amostral.…”