Preconditioning for long-duration transportation stress on beef cattle with rumen-protected methionine supplementation: a nutrigenetics study
Type of DegreeMaster's Thesis
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Different participants generally located distantly among them compose the U.S. beef production chain; therefore, shipping is required for cattle at least once in their lifespan. The aim of this study was to determine the effect of Rumen-Protected Methionine (RPM) supplementation on muscle fatigue gene network, creatine synthesis (CKM), and Reactive Oxygen Species (ROS) related-gene expression after 900 miles transportation simulation. Angus heifers (n = 18) were stratified by body weight (408 ± 64 kg; BW) and randomly assigned to dietary treatments: 1) control diet (CTRL), and 2) control diet + 8 gr/hd/day of rumen-protected methionine (RPM). After a successful adaptation period to Calan gates, animals received a common diet of Bermudagrass hay ad libitum and a soyhulls and corn gluten feed-based supplement. After 45 days under supplementation, animals were loaded onto a 32 × 7 ft. trailer and transported for 22 hours. Skeletal muscle biopsies, BW and blood samples were obtained on day 0 (Baseline; “BASE”), 43 (Pre-transport, “PRET”), and 45 (Post-transport, “POST”). Heifers’ average daily gain did not differ between BASE and PRET (P = 0.41). Control heifers’ shrink was 10% of BW whereas RPM heifers shrink was 8% (P = 0.82). Cortisol level decreased after transportation, but no differences were observed between treatments (P = 0.94). Circulating glucose and creatine kinase increased during transportation, but no difference was observed between treatments (P > 0.10). Messenger RNA was extracted from skeletal muscle tissue, and gene expression analysis was performed by RT-qPCR. Results showed that AHCY (Creatine synthesis pathway), SSPN (Sarcoglycan complex), DNMT3A (DNA Methylation), and SOD2 (Oxidative Stress-ROS) were upregulated (P < 0.05) in CTRL between BASE and PRET and decreased between PRET and POST (P < 0.05) while they remained unchanged for RPM. Furthermore, CKM (Creatine Kinase) was not affected by treatments (P = 0.11). In conclusion, muscle fatigue related genes were not affected by RPM. However, RPM effect on SOD2 gene suggests that it could affect ROS production after long-duration transportation.