Comparing responses of dairy cows to short-term and long-term heat stress in climate-controlled chambers

Hou, Yu; Zhang, Long; Dong, Renjie; Liang, Mingyue; Lu, Yunze; Sun, Xiaoqin; Zhao, Xin

doi:10.3168/jds.2020-18946

Cited by 31 publications

(17 citation statements)

References 30 publications

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“…For reasons that are not yet completely understood, heat stress is generally associated with increased circulating and MUN concentrations (Wheelock et al, 2010;Fatehi et al, 2012;Hou et al, 2021). In the current experiment, MUN was greater during HS than TN.…”

Section: Discussionmentioning

confidence: 52%

Comparison of production-related responses to hyperinsulinemia and hypoglycemia induced by clamp procedures or heat stress of lactating dairy cattle

Stewart

Arneson

Byrd

et al. 2022

Journal of Dairy Science

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Hyperinsulinemia concurrent with hypoglycemia is one of a myriad of physiological changes typically experienced by lactating dairy cows exposed to heat stress, the consequences of which are not yet well defined or understood. Therefore, the objective of this experiment was to separate the production-related effects of hyperinsulinemia with hypoglycemia from those of a hyperthermic environment. Multiparous lactating Holstein cows (n = 23; 58 ± 4 d in milk, 3.1 ± 0.3 lactations) were housed in temperature-controlled rooms and all were subjected to 4 experimental periods as follows: (1) thermoneutral (TN; temperature-humidity index of 65.1 ± 0.2; d 1-5), (2) TN + hyperinsulinemichypoglycemic clamp (HHC; insulin infused at 0.3 µg/ kg of BW per h, glucose infused to maintain 90 ± 10% of baseline blood glucose for 96 h; d 6-10), (3) heat stress (HS; temperature-humidity index of 72.5 ± 0.2; d 16-20), and (4) HS + euglycemic clamp (EC; glucose infused to reach 100 ± 10% of TN baseline blood glucose for 96 h; d 21-25). Cows were fed and milked twice daily. Feed refusals were collected once daily for calculation of daily dry matter intake, and milk samples were collected at the beginning and end of each period for component analyses. Circulating insulin concentrations were measured in daily blood samples, whereas glucose concentrations were measured more frequently and variably in association with clamp procedures. Rectal temperatures and respiration rates were greater during HS than TN, as expected, and states of hyperinsulinemia and hypoglycemia were successfully induced by the HHC and high ambient temperatures (HS and EC). Feed intake differed based upon thermal environment as it was similar during TN and HHC periods, and declined for HS and EC. Milk production was not entirely reflective of feed intake as it was greatest during TN, intermediate during HHC, and lowest during HS and EC. All milk components differed with the experimental period, primarily in response to the thermal environment. Interestingly, TN baseline glucose concentrations were highly correlated with the change in glucose from TN to HS, and were related to glycemic status during HS. Furthermore, although few in number, those cows that failed to become hypoglycemic during HS tended to have a greater reduction in milk yield. The work presented here addresses a critical knowledge gap by broadening our understanding of the physiological response to heat stress and the related changes in glycemic state. This broadened understanding is fundamental for the development of novel, innovative management strategies as the dairy industry is compelled to become increasingly efficient in spite of global warming.

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Section: Discussionmentioning

confidence: 52%

Comparison of production-related responses to hyperinsulinemia and hypoglycemia induced by clamp procedures or heat stress of lactating dairy cattle

Stewart

Arneson

Byrd

et al. 2022

Journal of Dairy Science

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“…HS affects the microbial environment of the rumen, causing an increase in pathogenic microorganisms, a decrease in adaptation pathways to the environment, and impaired immune responses and metabolic pathways [ 41 ]. Reduced feed intake and possible changes in rumen metabolism during HS led to a reduction in total and individual volatile fatty acid concentrations in rumen fluid [ 42 ]. Of these volatile fatty acids, acetic acid is an important substrate that has a strong impact on the expression of enzymes related to muscle growth [ 43 ].…”

Section: Discussionmentioning

confidence: 99%

Identification of Potential Biomarkers and Metabolic Pathways of Different Levels of Heat Stress in Beef Calves

Kim

Lee

2022

IJMS

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Heat stress (HS) damages the global beef industry by reducing growth performance causing high economic losses each year. However, understanding the physiological mechanisms of HS in Hanwoo calves remains elusive. The objective of this study was to identify the potential biomarkers and metabolic pathways involving different levels of heat stress in Hanwoo calves. Data were collected from sixteen Hanwoo bull calves (169.6 ± 4.6 days old, BW of 136.9 ± 6.2 kg), which were maintained at four designated ranges of HS according to the temperature–humidity index (THI) including: threshold (22 to 24 °C, 60%; THI = 70 to 73), mild (26 to 28 °C, 60%; THI = 74 to 76), moderate (29 to 31 °C, 80%; THI = 81 to 83), and severe (32 to 34 °C, 80%; THI = 89 to 91) using climate-controlled chambers. Blood was collected once every three days to analyze metabolomics. Metabolic changes in the serum of calves were measured using GC-TOF-MS, and the obtained data were calculated by multivariate statistical analysis. Five metabolic parameters were upregulated and seven metabolic parameters were downregulated in the high THI level compared with the threshold (p < 0.05). Among the parameters, carbohydrates (ribose, myo-inositol, galactose, and lactose), organic compounds (acetic acid, urea, and butenedioic acid), fatty acid (oleic acid), and amino acids (asparagine and lysine) were remarkably influenced by HS. These novel findings support further in-depth research to elucidate the blood-based changes in metabolic pathways in heat-stressed Hanwoo beef calves at different levels of THI. In conclusion, these results indicate that metabolic parameters may act as biomarkers to explain the HS effects in Hanwoo calves.

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“…Although altered ru-men pH is frequently reported, it is unclear whether ruminal pH typically decreases in dairy cows during HS events or if it reaches SARA levels. Indeed, a few studies even report that rumen pH increased during HS (Hall, 2009;Hou et al, 2021).…”

Section: Rumen Ph During Hsmentioning

confidence: 99%

“…Further, in those that did report pH, there are critical differences in trial protocols and execution that affect rumen pH. Notable differences affecting rumen pH include diet fermentability (Mishra et al, 1970;Gao et al, 2017), duration and frequency of pH measurement (Mishra et al, 1970;Schneider et al, 1988;Hall, 2009;Gao et al, 2017), the duration and extent of the imposed heat load (Gao et al, 2017), hydration status during the measurement period (Mishra et al, 1970;Schneider et al, 1988;Gao et al, 2017), DMI during the study, and differences in diurnal variation in heat exposure (Mishra et al, 1970;Schneider et al, 1988;Gao et al, 2017;Hou et al, 2021). It is also possible that reduced GIT BF during HS may compromise VFA absorption during HS, or that there is an interaction of consumed amounts of either water or DMI that confound the assessment of pH.…”

Section: Rumen Ph During Hsmentioning

confidence: 99%

Invited review: Lethal heat stress: The putative pathophysiology of a deadly disorder in dairy cattle

Burhans

Baumgard

2022

Journal of Dairy Science

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Heat stress (HS) reduces production and efficiency in almost every metric of the dairy operation, and it thus compromises profitability and sustainability. If the magnitude of HS progresses, it can become lethal. Death can occur acutely or days following the heat load, even if environmental conditions have become nonstressful. Consequently, lethal heat stress (LHS) is often difficult to identify and almost always misdiagnosed. The precise mechanisms of death when dairy cows succumb to LHS has not been fully elucidated or documented, but the pathophysiology of LHS appears to be conserved among several species. The unique digestive physiology of ruminants adds additional layers of complexity that contribute to failure of multiple systems involved with LHS. Consequently, the ostensible etiology and pathogenesis of LHS described herein is extended from the physiological adaptations cows use to survive HS and pertinent pathology extrapolated from other species. The multifactorial causes of death likely involve dysfunction and imbalance of several interdependent systems as follows: (1) electrolyte dyshomeostasis, (2) unstable blood pH, (3) gastrointestinal tract hyperpermeability, (4) sepsis, (5) severe immune activationinduced inflammation, (6) disseminated intravascular hypercoagulation, (7) systemic endothelial permeability, (8) multiple organ failure, and (9) circulatory failure. Having a better understanding of the mechanisms of LHS will improve diagnosis, enable a more accurate prognosis, and provide insight into strategies aimed at preventing dairy cow mortality and morbidity.

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Comparing responses of dairy cows to short-term and long-term heat stress in climate-controlled chambers

Cited by 31 publications

References 30 publications

Comparison of production-related responses to hyperinsulinemia and hypoglycemia induced by clamp procedures or heat stress of lactating dairy cattle

Comparison of production-related responses to hyperinsulinemia and hypoglycemia induced by clamp procedures or heat stress of lactating dairy cattle

Identification of Potential Biomarkers and Metabolic Pathways of Different Levels of Heat Stress in Beef Calves

Invited review: Lethal heat stress: The putative pathophysiology of a deadly disorder in dairy cattle

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