Inflammatory Mediation of Heat Stress-Induced Growth Deficits in Livestock and Its Potential Role as a Target for Nutritional Interventions: A Review

Heat stress is detrimental to well-being and growth performance in livestock, and systemic inflammation arising during chronic heat stress contributes to these poor outcomes. Sustained exposure of muscle and other tissues to inflammation can impair the cellular processes that facilitate muscle growth and intramuscular fat deposition, thus reducing carcass quality and yield. Climate change is expected to produce more frequent extreme heat events, increasing the potential impact of heat stress on sustainable livestock production. Feedlot animals are at particularly high risk for heat stress, as confinement limits their ability to seek cooling from the shade, water, or breeze. Economically practical options to circumvent heat stress in feedlot animals are limited, but understanding the mechanistic role of inflammation in heat stress outcomes may provide the basis for treatment strategies to improve well-being and performance. Feedlot animals receive formulated diets daily, which provides an opportunity to administer oral nutraceuticals and other bioactive products to mitigate heat stress-induced inflammation. In this review, we examine the complex associations between heat stress, systemic inflammation, and dysregulated muscle growth in meat animals. We also present evidence for potential nutraceutical and dietary moderators of inflammation and how they might improve the unique pathophysiology of heat stress.

Download Full-text

Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs

Journal of Animal Science ◽

10.1093/jas/skaa168 ◽

2020 ◽

Vol 98 (6) ◽

Cited By ~ 1

Author(s):

Rebecca M Swanson ◽

Richard G Tait ◽

Beth M Galles ◽

Erin M Duffy ◽

Ty B Schmidt ◽

...

Keyword(s):

Heat Stress ◽

Systemic Inflammation ◽

Feed Intake ◽

White Blood Cells ◽

Well Being ◽

Fat Content ◽

Left Ventricular ◽

Metabolic Efficiency ◽

Feedlot Lambs ◽

The Impact

Abstract Heat stress hinders growth and well-being in livestock, an effect that is perhaps exacerbated by the β1 agonist ractopamine. Heat stress deficits are mediated in part by reduced feed intake, but other mechanisms involved are less understood. Our objective was to determine the direct impact of heat stress on growth and well-being in ractopamine-supplemented feedlot lambs. Commercial wethers were fed under heat stress (40 °C) for 30 d, and controls (18 °C) were pair-fed. In a 2 × 2 factorial, lambs were also given a daily gavage of 0 or 60 mg ractopamine. Growth, metabolic, cardiovascular, and stress indicators were assessed throughout the study. At necropsy, 9th to 12th rib sections (four-rib), internal organs, and feet were assessed, and sartorius muscles were collected for ex vivo glucose metabolic studies. Heat stress increased (P < 0.05) rectal temperatures and respiration rates throughout the study and reduced (P < 0.05) weight gain and feed efficiency over the first week, ultrasonic loin-eye area and loin depth near the end of the study, and four-rib weight at necropsy. Fat content of the four-rib and loin were also reduced (P < 0.05) by heat stress. Ractopamine increased (P < 0.05) loin weight and fat content and partially moderated the impact of heat stress on rectal temperature and four-rib weight. Heat stress reduced (P < 0.05) spleen weight, increased (P < 0.05) adrenal and lung weights, and was associated with hoof wall overgrowth but not organ lesions. Ractopamine did not affect any measured indicators of well-being. Heat stress reduced (P < 0.05) blood urea nitrogen and increased (P < 0.05) circulating monocytes, granulocytes, and total white blood cells as well as epinephrine, TNFα, cholesterol, and triglycerides. Cortisol and insulin were not affected. Heat stress reduced (P < 0.05) blood pressure and heart rates in all lambs and increased (P < 0.05) left ventricular wall thickness in unsupplemented but not ractopamine-supplemented lambs. No cardiac arrhythmias were observed. Muscle glucose uptake did not differ among groups, but insulin-stimulated glucose oxidation was reduced (P < 0.05) in muscle from heat-stressed lambs. These findings demonstrate that heat stress impairs growth, metabolism, and well-being even when the impact of feed intake is eliminated by pair-feeding and that systemic inflammation and hypercatecholaminemia likely contribute to these deficits. Moreover, ractopamine improved muscle growth indicators without worsening the effects of heat stress.

Download Full-text

Estimation of the efficiency of cowshed aeration in the warm season

The Agrarian Scientific Journal ◽

10.28983/asj.y2020i12pp85-86 ◽

2020 ◽

pp. 85-86

Author(s):

Kaminat Muradovna Agakhanova

Keyword(s):

Heat Stress ◽

Air Temperature ◽

Warm Season ◽

Well Being ◽

Factors Affecting ◽

Daily Change ◽

Main Factors ◽

And Performance ◽

Air Exchange

Heat stress is one of the main factors affecting the well-being and performance of cows during the warm season. The article presents the results of calculating the daily change in the ventilation air consumption during the cowshed aeration. The influence of changes in the outside air temperature on the amount of air exchange was revealed.

Download Full-text

423 WS Young Scholar Talk MS II: Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs

Journal of Animal Science ◽

10.1093/jas/skaa278.374 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 202-203 ◽

Cited By ~ 1

Author(s):

Rebecca M Swanson

Keyword(s):

Heat Stress ◽

Systemic Inflammation ◽

Muscle Growth ◽

Growth Efficiency ◽

Postnatal Growth ◽

Metabolic Efficiency ◽

Maternal Condition ◽

Growth Metabolism ◽

Capacity Data ◽

The Impact

Abstract Our 1st study evaluated the effects of □-adrenergic agonist (ractopamine) supplementation on growth, health, and wellbeing in heat-stressed feedlot wethers. Chronic heat stress impaired growth, metabolism, and wellbeing even when the impact of reduced feed intake was eliminated by pair-feeding. We observed systemic inflammation and hypercatecholaminemia that were likely mediators of these deficits. Moreover, ractopamine did not diminish any wellbeing indicators and improved muscle growth without worsening the effects of heat stress. Our 2nd study assessed the effects of pubertal cyclicity (weaning to 1st breeding) in cows on myoblast-mediated muscle growth, metabolism, and growth efficiency of their offspring. Maternal fertility and postnatal growth efficiency of offspring are imperative to successful beef cattle production. A maternal condition was previously identified in which cows exhibited irregular cyclicity patterns or were non-cyclic between weaning and 1st breeding. This condition is thought to be associated with high concentrations of androstenedione in their follicular fluid, which causes cows to be sub-fertile but also wean heavier calves when they do become pregnant. We hypothesized that calves from cows exhibiting irregular pubertal cyclicity would have enhanced growth efficiency compared to calves from cows with normal pubertal cyclicity. To test this hypothesis, we evaluated myoblast function, growth, and metabolism pre-weaning, as well as growth efficiency in the feedlot and carcass characteristics at harvest in calves from cows that were previously identified as having typical, start-stop, or non-cycling pubertal cyclicity patterns. Calves from irregular cycling cows had reductions in insulin sensitivity, plasma proteins and lipids paired with increased myoblast function and reduced myoblast glycolytic capacity. Data independently and combined suggest calves from cows with irregular cyclicity from weaning to 1st breeding have chronic inflammation. While the specific mechanism of inflammation is unknown, further research may allow mediators of abnormal cyclicity and offspring inflammation-induced dysfunction to be elucidated.

Download Full-text

Managing Heat and Immune Stress in Athletes With Evidence-Based Strategies

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2014-0232 ◽

2014 ◽

Vol 9 (5) ◽

pp. 744-750 ◽

Cited By ~ 11

Author(s):

David B. Pyne ◽

Joshua H. Guy ◽

Andrew M. Edwards

Keyword(s):

Heat Stress ◽

Heat Acclimation ◽

Well Being ◽

Coagulation Cascade ◽

Heat Management ◽

Immune Stress ◽

Stress Studies ◽

Wide Range ◽

Thermoregulatory Model ◽

And Performance

Heat and immune stress can affect athletes in a wide range of sports and environmental conditions. The classical thermoregulatory model of heat stress has been well characterized, as has a wide range of practical strategies largely centered on cooling and heat-acclimation training. In the last decade evidence has emerged of an inflammatory pathway that can also contribute to heat stress. Studies are now addressing the complex and dynamic interplay between hyperthermia, the coagulation cascade, and a systemic inflammatory response occurring after transient damage to the gastrointestinal tract. Damage to the intestinal mucosal membrane increases permeability, resulting in leakage of endotoxins into the circulation. Practical strategies that target both thermoregulatory and inflammatory causes of heat stress include precooling; short-term heat-acclimation training; nutritional countermeasures including hydration, energy replacement, and probiotic supplementation; pacing strategies during events; and postevent cooling measures. Cooperation between international, national, and local sporting organizations is required to ensure that heat-management policies and strategies are implemented effectively to promote athletes’ well-being and performance.

Download Full-text

Technologies for the automated collection of heat stress data in sheep

Animal Biotelemetry ◽

10.1186/s40317-020-00225-9 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Bobbie E. Lewis Baida ◽

Alyce M. Swinbourne ◽

Jamie Barwick ◽

Stephan T. Leu ◽

William H. E. J. van Wettere

Keyword(s):

Heat Stress ◽

Real Time ◽

Climate Models ◽

Reproductive Function ◽

Well Being ◽

Time Data ◽

Management Decisions ◽

Positioning Systems ◽

Ambient Temperatures ◽

And Performance

AbstractThe automated collection of phenotypic measurements in livestock is becoming increasingly important to both researchers and farmers. The capacity to non-invasively collect real-time data, provides the opportunity to better understand livestock behaviour and physiology and improve animal management decisions. Current climate models project that temperatures will increase across the world, influencing both local and global agriculture. Sheep that are exposed to high ambient temperatures experience heat stress and their physiology, reproductive function and performance are compromised. Body temperature is a reliable measure of heat stress and hence a good indicator of an animals’ health and well-being. Non-invasive temperature-sensing technologies have made substantial progress over the past decade. Here, we review the different technologies available and assess their suitability for inferring ovine heat stress. Specifically, the use of indwelling probes, intra-ruminal bolus insertion, thermal imaging and implantable devices are investigated. We further evaluate the capacity of behavioural tracking technology, such as global positioning systems, to identify heat stressed individuals based on the exhibition of specific behaviours. Although there are challenges associated with using real-time thermosensing data to make informed management decisions, these technologies provide new opportunities to manage heat stress in sheep. In order to obtain accurate real-time information of individual animals and facilitate prompt intervention, data collection should be entirely automated. Additionally, for accurate interpretation on-farm, the development of software which can effectively collect, manage and integrate data for sheep producer’s needs to be prioritised. Lastly, understanding known physiological thresholds will allow farmers to determine individual heat stress risk and facilitate early intervention to reduce the effects in both current and subsequent generations.

Download Full-text

Diffuse reflectance spectroscopy reveals heat stress-induced changes in hemoglobin concentration in chicken breast

Scientific Reports ◽

10.1038/s41598-021-83293-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sina Dadgar ◽

Elizabeth Greene ◽

Ahmed Dhamad ◽

Barbara Mallmann ◽

Sami Dridi ◽

...

Keyword(s):

Heat Stress ◽

Diffuse Reflectance ◽

Diffuse Reflectance Spectroscopy ◽

Hematological Parameters ◽

Hemoglobin Concentration ◽

Well Being ◽

Blood Chemistry ◽

Reflectance Spectroscopy ◽

Chicken Breast ◽

And Performance

AbstractHeat stress (HS) is devastating to the poultry industry due to its adverse effects on animal well-being and performance. The effects of heat stress are typically measured using a portable i-STAT blood analyzer that quantifies circulatory hemoglobin concentration and other blood chemistry parameters. Here, we used diffuse reflectance spectroscopy (DRS) as a novel non-invasive method to directly determine changes in hematological parameters in the breast tissues of live heat-stressed broilers. Three-week-old male broilers were randomly subjected to two environmental conditions (thermoneutral, TN, 24 °C vs. cyclic heat stress, HS, 35 °C, 12 h/day). Optical spectra were acquired using DRS to monitor breast hemoglobin (Hb) concentration and vascular oxygen saturation (sO2) at three time points: at baseline prior to heat stress, 2 days, and 21 days after initiation of HS. While i-STAT did not demonstrate a discernible change due to HS in circulatory hemoglobin, DRS found a significant decrease in breast Hb and sO2 after exposure to chronic HS. The decrease in sO2 was found to be due to a decrease in oxygenated hemoglobin concentration, indicating a large increase in oxygen consumption in heat-stressed broilers. Our results demonstrate that DRS could potentially be used to study the effects of HS directly in specific organs of interest, such as the breast and thigh, to improve meat quality.

Download Full-text