Pulmonary arterial pressure in fattened Angus steers at moderate altitude influences early postmortem mitochondria functionality and meat color during retail display

Abstract

Pulmonary hypertension is a noninfectious disease of cattle at altitudes > 1524 m (5,000 ft). Mean pulmonary arterial pressures (PAP) are used as an indicator for pulmonary hypertension in cattle. High PAP cattle (≥ 50 mmHg) entering the feedlot at moderate elevations have lower feed efficiency as compared to low PAP cattle (< 50 mmHg). The impact of pulmonary arterial pressure on mitochondrial function, oxidative phosphorylation (OXPHOS) protein abundance, and meat color was examined using longissimus lumborum (LL) from high (98 ± 13 mmHg; n = 5) and low (41 ± 3 mmHg; n = 6) PAP fattened Angus steers (live weight of 588 ± 38 kg) during early postmortem period (2 h and 48 h) and retail display (day 1 to 9), respectively. High PAP muscle had greater (P = 0.013) OXPHOS-linked respiration and proton leak-associated respiration than low PAP muscles at 2 h postmortem but rapidly declined to be similar (P = 0.145) to low PAP muscle by 48 h postmortem. OXPHOS protein expression was higher (P = 0.045) in low PAP than high PAP muscle. During retail display, redness, chroma, hue, ratio of reflectance at 630 nm and 580 nm, and metmyoglobin reducing activity decreased faster (P < 0.05) in high PAP steaks than low PAP. Lipid oxidation significantly increased (P < 0.05) in high PAP steaks but not (P > 0.05) in low PAP. The results indicated that high PAP caused a lower OXPHOS efficiency and a greater fuel oxidation rates under conditions of low ATP demand in premortem beef LL muscle, this could explain the lower feed efficiency in high PAP feedlot cattle compared to low PAP counterparts. Mitochondrial integral function (membrane integrity or/and protein function) declined faster in high PAP than low PAP muscle at early postmortem. LL steaks from high PAP animals had lower color stability than those from the low PAP animals during simulated retail display, which could be partially attributed to the loss of muscle mitochondrial function at early postmortem by ROS damage in high PAP muscle. Pulmonary arterial hypertension could also decrease type I/type II muscle fiber ratio in skeletal muscle, which needs to be investigated further.

Deciphering Tissue-Specific Expression Profiles of Mitochondrial Genome-encoded tRNAs and rRNAs through Transcriptomic Profiling in Buffalo

“…Mammalian tissues, re ecting diverse energy demands, exhibit signi cant variations in metabolic pro les, which can dynamically change throughout development in response to physiological adaptations and under pathological conditions (Alston et al, 2017;Sadeesh et al, 2023a). Furthermore, the quality of meat is also in uenced by mitochondrial functionality and the distinct proteome pro les of mitochondria (Ramanathan et al, 2021;Zhai et al, 2022). This divergence in mitochondrial function re ects the unique energy demands and metabolic priorities of different tissue types, highlighting the relevance of our study in exploring the differential expression of non-coding RNAs crucial for mtDNA-encoded protein expression across diverse tissues.…”

Nuclear genome-encoded mitochondrial OXPHOS complex I genes in Buffalo show tissue-specific differences

“…Moreover, mitochondrial functionality and differential mitochondrial proteome pro les also in uence meat quality [31]. Even high-altitude disorders in cattle affect the mitochondrial integral function, which impacts beef quality [32]. Extensive research has been conducted on mitochondrial transcriptome variances among various tissues in human and rodent models.…”