Nutritional Interventions to Alleviate the Negative Consequences of Heat Stress

Abstract

Energy metabolism is a highly coordinated process, and preferred fuel(s) differ among tissues. The hierarchy of substrate use can be affected by physiological status and environmental factors including high ambient temperature. Unabated heat eventually overwhelms homeothermic mechanisms resulting in heat stress, which compromises animal health, farm animal production, and human performance. Various aspects of heat stress physiology have been extensively studied, yet a clear understanding of the metabolic changes occurring at the cellular, tissue, and whole-body levels in response to an environmental heat load remains ill-defined. For reasons not yet clarified, circulating nonesterified fatty acid levels are reduced during heat stress, even in the presence of elevated stress hormones (epinephrine, glucagon, and cortisol), and heat-stressed animals often have a blunted lipolytic response to catabolic signals. Either directly because of or in coordination with this, animals experiencing environmental hyperthermia exhibit a shift toward carbohydrate use. These metabolic alterations occur coincident with increased circulating basal and stimulated plasma insulin concentrations. Limited data indicate that proper insulin action is necessary to effectively mount a response to heat stress and minimize heat-induced damage. Consistent with this idea, nutritional interventions targeting increased insulin action may improve tolerance and productivity during heat stress. Further research is warranted to uncover the effects of heat on parameters associated with energy metabolism so that more appropriate and effective treatment methodologies can be designed.

Impact of the Egyptian summer season on oxidative stress biomarkers and some physiological parameters in crossbred cows and Egyptian buffaloes

“…The significant negative correlation between animal's RT and its DMI was previously reported in Holsteins [25]. According to Rhoads et al, feed intake started to decrease at air temperatures of 25-26°C in dairy cows and dramatically declined above 30°C in moderate climatic condition and at 40°C [30], it may decrease by as much as 40%. Moreover, the same correlation was demonstrated in buffaloes as up to 40% reduction in voluntary DMI during the summer months was recorded as compared to the amount consumed during the cooler months [31].…”

Effects of heat stress on serum insulin, adipokines, AMP-activated protein kinase, and heat shock signal molecules in dairy cows

“…No significant differences were observed in serum concentrations of insulin between HS and CL (P>0.05; Table 3). Li et al (2006) and Rhoads et al (2013) pointed out that proper insulin action is necessary to effectively mount a response to heat stress and minimize heat-induced damage. It is generally known that heat stress stimulates the concentrations of insulin (O'Brien et al, 2010;Wheelock et al, 2010).…”

Influence of supplementing diet with microalgae (Schizochytrium limacinum)on growth and metabolism in lambs during the summer

“…The combination of summer temperature and humidity limit animal production, compromise the immune system, and negatively affect animal health (1). Success in overcoming the effects of heat stress is very likely related to the heat increment of feeds (2).…”