Thyroid hormones correlate with field metabolic rate in ponies, Equus ferus caballus.
Abstract: During winter, free-living herbivores are often exposed to reduced energy supply at the same time that energy needs for thermoregulation increase. Several wild herbivores as well as robust horse breeds reduce their metabolism during times of low ambient temperature and food shortage. Thyroid hormones (THs) affect metabolic intensity and a positive effect of THs on basal metabolic rate (BMR) has been demonstrated in mammals and birds. As BMR and field metabolic rate (FMR) are often assumed to be intrinsically linked, THs may represent a reliable indicator for FMR. To test this hypothesis, 10 Shetland pony mares were kept under semi-extensive central European conditions. During the winter season, one group was fed 60% and one group 100% of their maintenance energy requirements. We measured FMR, locomotor activity, resting heart rate and TH levels in summer and winter. FMR, locomotor activity, resting heart rate and total T3 concentrations decreased substantially in winter compared with summer, whereas total T4 increased. Food restriction led to a reduced FMR and resting heart rate, while THs and locomotor activity were not affected. Across both seasons, FMR, resting heart rate and locomotor activity were positively correlated with total T3 but negatively and more weakly correlated with total T4.
© 2016. Published by The Company of Biologists Ltd.
Publication Date: 2016-06-16 PubMed ID: 27312472DOI: 10.1242/jeb.138784Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the correlation between thyroid hormone levels and metabolic rates in ponies during different seasons and under varying food availability. Researchers observed that thyroid hormones, specifically total T3, seem to be reliable indicators of field metabolic rates (FMR) in Shetland pony mares, with levels declining in winter alongside decreases in FMR, locomotor activity, and resting heart rate.
Research Methodology and Sample Population
- The sample for this study comprised 10 Shetland pony mares, kept under semi-extensive central European conditions.
- These ponies experience both summer and winter seasons, which allowed for a distinctive comparison.
- During winter, the ponies were split into two groups – one fed with 60% and the other with 100% of their maintenance energy requirements.
Measurements and Results
- The researchers measured FMR, locomotor activity, resting heart rate, and thyroid hormone (TH) levels in both summer and winter seasons.
- They found a significant decrease in FMR, locomotor activity, resting heart rate, and total T3 concentration in winter compared to summer.
- On the contrary, total T4 levels increased in the winter.
- Food restriction resulted in a decrease in FMR and the resting heart rate, but it had no impact on TH levels and locomotor activity.
Correlation of THs with Metabolic Rates
- The research demonstrated a positive correlation between total T3 and FMR, resting heart rate, and locomotor activity across both seasons.
- More specifically, when the total T3 level was high, the FMR, heart rate, and locomotor activity were also high. The reverse was also observed.
- Total T4, however, had a weaker and negative correlation with these metabolic rates.
Significance of the Findings
- The study highlights the potential role of thyroid hormones as indicators of metabolic intensity in mammals during periods of energy scarcity.
- The findings underscore the adaptive mechanisms of herbivores during winter, showing that a reduction in metabolism and related activities is a survival strategy during low temperatures and food scarcity.
- The results could have implications for the care and management of domestic horses and other herbivores, especially in areas with marked seasonal variation.
Cite This Article
APA
Brinkmann L, Gerken M, Hambly C, Speakman JR, Riek A.
(2016).
Thyroid hormones correlate with field metabolic rate in ponies, Equus ferus caballus.
J Exp Biol, 219(Pt 16), 2559-2566.
https://doi.org/10.1242/jeb.138784 Publication
Researcher Affiliations
- Department of Animal Sciences, University of Göttingen, Göttingen 37075, Germany.
- Department of Animal Sciences, University of Göttingen, Göttingen 37075, Germany.
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK Institute of Genetics and Developmental Biology, State Key Laboratory of Molecular Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China.
- Department of Animal Sciences, University of Göttingen, Göttingen 37075, Germany ariek@uni-goettingen.de.
MeSH Terms
- Animals
- Basal Metabolism / physiology
- Body Weight
- Energy Metabolism / physiology
- Europe
- Female
- Horses / metabolism
- Locomotion / physiology
- Rest / physiology
- Seasons
- Thyroid Hormones / metabolism
Citations
This article has been cited 10 times.- Ishimaru M, Tsuchiya T, Endo Y, Matsui A, Ohmura H, Murase H, Korosue K, Sato F, Taya K. Effects of different winter paddock management of Thoroughbred weanlings and yearlings in the cold region of Japan on physiological function, endocrine function and growth. J Vet Med Sci 2024 Jul 2;86(7):756-768.
- Gasch K, Habe M, Krauss JS, Painer-Gigler J, Stalder G, Arnold W. The Influence of Photoperiod, Intake of Polyunsaturated Fatty Acids, and Food Availability on Seasonal Acclimatization in Red Deer (Cervus elaphus). Animals (Basel) 2023 May 10;13(10).
- Rudolf AM, Wu Q, Li L, Wang J, Huang Y, Togo J, Liechti C, Li M, Niu C, Nie Y, Wei F, Speakman JR. A single nucleotide mutation in the dual-oxidase 2 (DUOX2) gene causes some of the panda's unique metabolic phenotypes. Natl Sci Rev 2022 Feb;9(2):nwab125.
- Tremblay F, Whelan S, Choy ES, Hatch SA, Elliott KH. Resting costs too: the relative importance of active and resting energy expenditure in a sub-arctic seabird. J Exp Biol 2022 Feb 15;225(4).
- Shultz S, Britnell JA, Harvey N. Untapped potential of physiology, behaviour and immune markers to predict range dynamics and marginality. Ecol Evol 2021 Dec;11(23):16446-16461.
- Speakman JR, Chi Q, Ołdakowski Ł, Fu H, Fletcher QE, Hambly C, Togo J, Liu X, Piertney SB, Wang X, Zhang L, Redman P, Wang L, Tang G, Li Y, Cui J, Thomson PJ, Wang Z, Glover P, Robertson OC, Zhang Y, Wang D. Surviving winter on the Qinghai-Tibetan Plateau: Pikas suppress energy demands and exploit yak feces to survive winter. Proc Natl Acad Sci U S A 2021 Jul 27;118(30).
- Siwinska N, Zak A, Baron M, Cylna M, Borowicz H. Right dorsal colon ultrasonography in normal adult ponies and miniature horses. PLoS One 2017;12(10):e0186825.
- Tangyuenyong S, Sato F, Nambo Y, Murase H, Endo Y, Tanaka T, Nagaoka K, Watanabe G. Comparison of physical body growth and metabolic and reproductive endocrine functions between north and south climates of Japan in trained Thoroughbred yearling horses. J Equine Sci 2017;28(3):77-86.
- Tangyuenyong S, Nambo Y, Nagaoka K, Tanaka T, Watanabe G. Sensitive radioimmunoassay of total thyroxine (T4) in horses using a simple extraction method. J Vet Med Sci 2017 Jul 28;79(7):1294-1300.
- Swanson DL, McKechnie AE, Vézina F. How low can you go? An adaptive energetic framework for interpreting basal metabolic rate variation in endotherms. J Comp Physiol B 2017 Dec;187(8):1039-1056.
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