Rapid Communication: Differential skeletal muscle mitochondrial characteristics of weanling racing-bred horses.
Abstract: Responses of equine skeletal muscle characteristics to growth and training have been shown to differ between breeds. These differential responses may arise in part because muscle fiber type and mitochondrial density differ between breeds, even in untrained racing-bred horses. However, it is not known when these breed-specific differences manifest. To test the hypothesis that weanling Standardbreds (SB) and Thoroughbreds (TB) would have higher mitochondrial measures than Quarter Horses (QH), gluteus medius samples were collected from SB (mean ± SD; 6.2 ± 1.0 mo; n = 10), TB (6.1 ± 0.5 mo; n = 12), and QH (7.4 ± 0.6 mo; n = 10). Citrate synthase (CS) and cytochrome c oxidase (CCO) activities were assessed as markers of mitochondrial density and function, respectively. Mitochondrial oxidative (P) and electron transport system (E) capacities were assessed by high-resolution respirometry (HRR). Data for CCO and HRR are expressed as integrated (per mg protein and per mg tissue wet weight, respectively) and intrinsic (per unit CS). Data were analyzed using PROC MIXED in SAS v 9.4 with breed as a fixed effect. Mitochondrial density (CS) was higher for SB and TB than QH (P ≤ 0.0007). Mitochondrial function (integrated and intrinsic CCO) was higher in TB and QH than SB (P ≤ 0.01). Integrated CCO was also higher in TB than QH (P < 0.0001). However, SB had higher integrated maximum P (PCI+II) and E (ECI+II) than QH (P ≤ 0.02) and greater integrated and intrinsic complex II-supported E (ECII) than both QH and TB (P ≤ 0.02), while TB exhibited higher integrated P with complex I substrates (PCI) than SB and QH (P ≤ 0.003) and higher integrated PCI+II and ECI+II than QH (P ≤ 0.02). In agreement, TB and QH had higher contribution of complex I (CI) to max E than SB (P ≤ 0.001), while SB had higher contribution of CII than QH and TB (P ≤ 0.002). Despite having higher mitochondrial density than QH and TB, SB showed lower CCO activity and differences in contribution of complexes to oxidative and electron transport system capacities. Breed differences in mitochondrial parameters are present early in life and should be considered when developing feeding, training, medication, and management practices.
© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Publication Date: 2019-06-17 PubMed ID: 31211376DOI: 10.1093/jas/skz203Google Scholar: Lookup
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- Journal Article
Summary
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The research examined the differences in muscle characteristics and mitochondrial density in weanling Standardbreds, Thoroughbreds, and Quarter Horses to determine breed-specific conditions. The study found that these differences manifest early in life and may impact feeding, training, and management practices.
Study Objective
- The intention of the research was to test whether weanling Standardbreds (SB) and Thoroughbreds (TB) possess higher mitochondrial measures than Quarter Horses (QH). This evaluation was necessary to identify when breed-specific differences in muscle characteristics and mitochondrial density manifest. The understanding of such differences might influence the development of feeding, training, medication, and management practices for each breed.
Methodology
- The study involved the collection of gluteus medius samples from each of the three horse breeds: Standardbreds (average age ± SD; 6.2 ± 1.0 months; total = 10), Thoroughbreds (6.1 ± 0.5 months; total = 12), and Quarter Horses (7.4 ± 0.6 months; total = 10).
- The research made use of two markers, Citrate synthase (CS) and cytochrome c oxidase (CCO), to gauge mitochondrial density and function respectively. Also, mitochondrial oxidative and electron transport system capacities were assessed through high-resolution respirometry (HRR).
- Data were subsequently analyzed using PROC MIXED in SAS v 9.4 considering the breed as a fixed effect.
Findings
- The results showed that the mitochondrial density (CS) was higher for Standardbreds and Thoroughbreds compared to Quarter Horses.
- The mitochondrial function (integrated and intrinsic CCO) was higher in Thoroughbreds and Quarter Horses than in Standardbreds. Furthermore, integrated CCO was also higher in Thoroughbreds than in Quarter Horses.
- Despite having a higher mitochondrial density than Quarter Horses and Thoroughbreds, Standardbreds exhibited lower CCO activity and differences in the contribution of complexes to oxidative and electron transport system capacities.
- The differences in mitochondrial parameters among the breeds manifest early in life.
Implications
- The breed-specific variations in muscle characteristics and mitochondrial density found in the study suggest that different training, feeding, medication, and management methods may be required for each horse breed. It also suggests that these practices should be developed and implemented early in the horses’ life.
Cite This Article
APA
Latham CM, Fenger CK, White SH.
(2019).
Rapid Communication: Differential skeletal muscle mitochondrial characteristics of weanling racing-bred horses.
J Anim Sci, skz203.
https://doi.org/10.1093/jas/skz203 Publication
Researcher Affiliations
- Texas A&M University, College Station, TX.
- Equine Integrated Medicine, PLC, Georgetown, KY.
- Texas A&M University, College Station, TX.
Citations
This article has been cited 6 times.- Owen RN, Semanchik PL, Latham CM, Brennan KM, White-Springer SH. Elevated dietary selenium rescues mitochondrial capacity impairment induced by decreased vitamin E intake in young exercising horses. J Anim Sci 2022 Aug 1;100(8).
- Dungan CM, Brightwell CR, Wen Y, Zdunek CJ, Latham CM, Thomas NT, Zagzoog AM, Brightwell BD, VonLehmden GL, Keeble AR, Watowich SJ, Murach KA, Fry CS. Muscle-Specific Cellular and Molecular Adaptations to Late-Life Voluntary Concurrent Exercise. Function (Oxf) 2022;3(4):zqac027.
- Latham CM, Guy CP, Wesolowski LT, White-Springer SH. Fueling equine performance: importance of mitochondrial phenotype in equine athletes. Anim Front 2022 Jun;12(3):6-14.
- Henry ML, Wesolowski LT, Pagan JD, Simons JL, Valberg SJ, White-Springer SH. Impact of Coenzyme Q10 Supplementation on Skeletal Muscle Respiration, Antioxidants, and the Muscle Proteome in Thoroughbred Horses. Antioxidants (Basel) 2023 Jan 24;12(2).
- Latham CM, Owen RN, Dickson EC, Guy CP, White-Springer SH. Skeletal Muscle Adaptations to Exercise Training in Young and Aged Horses. Front Aging 2021;2:708918.
- Owen RN, Latham CM, Long CR, Randel RD, Welsh TH, White-Springer SH. Temperament influences mitochondrial capacity in skeletal muscle from 8 through 18 mo of age in Brahman heifers. J Anim Sci 2020 Oct 1;98(10).
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