|Artegoitia Etchev, Virginia|
|LEWIS, RON - University Of Nebraska|
|FOOTE, ANDREW - Former ARS Employee|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2020
Publication Date: N/A
Technical Abstract: A discovery project to identify non-invasive biomarkers that can detect subtle metabolic discrepancies for cattle feed efficiency was performed using untargeted and targeted urine metabolomics by ultra-performance liquid chromatography-mass spectrometry. Individual feed intake and body weight gain were measured in crossbred steers (n =80) on a forage-based growing ration (stage-1) followed by a high-concentrate diet finishing ration (stage-2). Urine was collected on study days 0, 21, 42, 63, and 83 for each dietary stage. In total 28 steers with the greatest and the least average daily-gain (ADG) within 0.32 SD of the mean of dry-matter-intake (DMI) were used. A principal component analysis of the untargeted metabolites fully segregated the highest-ADG and lowest-ADG animals, with overlap across diets (both stages). The urinary untargeted metabolites that segregated the ADG-groups (n =199; P <0.05), included steroid-hormones, bile-acids, alpha-linolenic acid metabolites, vitamin-B6, along with products of glycine, serine and threonine metabolism (metabolic pathway analysis: impact-value >0.50; FDR <0.10). Bile acids and steroids were then quantified in urine and their associations with animal performance and carcass composition evaluated by correlation and multiple logistic regression AUC-ROC curve analyses. In stage-1, urine concentration of cortisone was associated (P <0.05) with ADG (r =-0.28), DMI (r =-0.40) and ribeye-area (r =-0.28); cortisol was associated with DMI (r =-0.32; P <0.01) and testosterone was associated with ADG (r =-0.28; P <0.01). The urine concentrations of 18 measured bile acids were negatively associated (P <0.05) with DMI, and secondary bile acids were negatively associated (P <0.01) with marbling and hot-carcass-weight. In stage-2, negative association between the bile acids glycocholic acid and deoxycholic acid with marbling and hot-carcass-weight were identified. Urine metabolomics provide new insight into the physiological mechanisms and potential biomarkers of cattle feed efficiency.