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Indicator traits associated with disease resiliency would be useful to improve the health and welfare of feedlot cattle. A post hoc analysis of data collected previously (Kayser et al., 2019a) was conducted to investigate differences in immunologic, physiologic, and behavioral responses of steers (N = 36, initial BW = 386 ± 24 kg) that had differential haptoglobin (HPT) responses to an experimentally induced challenge with Mannheimia haemolytica (MH). Rumen temperature, DMI, and feeding behavior data were collected continuously, and serial blood samples were collected following the MH challenge. Retrospectively, it was determined that 9 of the 18 MH-challenged steers mounted a minimal HPT response, despite having similar leukocyte and temperature responses to other MH-challenged steers with a greater HPT response. Our objective was to examine differences in behavioral and physiological responses between MH-challenged HPT responsive (RES; n = 9), MH-challenged HPT nonresponsive (NON; n = 9), and phosphate-buffered saline-inoculated controls (CON; n = 18). Additionally, 1H NMR analysis was conducted to determine whether the HPT responsive phenotype affected serum metabolite profiles. The RES steers had lesser (P < 0.05) cortisol concentrations than NON and CON steers. The magnitude of the increases in neutrophil concentrations and rumen temperature, and the reduction in DMI following the MH challenge were greatest (P < 0.05) in RES steers. Univariate analysis of serum metabolites indicated differences between RES, NON, and CON steers following the MH challenge; however, multivariate analysis revealed no difference between HPT-responsive phenotypes. Prior to the MH challenge, RES steers had longer (P < 0.05) head down and bunk visit durations, slower eating rates (P < 0.01) and greater (P < 0.05) daily variances in bunk visit frequency and head down duration compared with NON steers, suggesting that feeding behavior patterns were associated with the HPT-responsive phenotype. During the 28-d post challenge period, RES steers had decreased (P < 0.05) final BW, tended (P = 0.06) to have lesser DMI, and had greater (P < 0.05) daily variances in head down and bunk visit durations compared with NON steers, which may have been attributed to their greater acute-phase protein response to the MH challenge. These results indicate that the HPT-responsive phenotype affected feeding behavior patterns and may be associated with disease resiliency in beef cattle. [ABSTRACT FROM AUTHOR]

Backfat and carcass fatness is an important quality attribute in meat animals. A substantial economic gain in the livestock industry may result from the discovery of metabolites, which can improve methods for predicting desirable livestock traits before harvest. Complex phenotypes can be identified for genetic selection or precision management using metabolic and genetic biomarkers. An analysis of ovine samples collected before harvest from wethers with different degrees of back fat was conducted using serum samples obtained from 15 sheep (5 from each back fat class), 60 d, 30 d, and just before harvest. This study quantified 55 serum metabolites that play important roles in ovine metabolism by 1H nuclear magnetic resonance (NMR) spectroscopy. An RNAseq dataset was generated from each sheep's muscle and adipose tissue at harvest. A statistical analysis of the data was performed using MetaboAnalyst Version 5.0 software in R. The results of multiple analyses showed that three metabolites, betaine, choline, and dimethylamine, are associated with sheep's fat class at a significance of (P < 0.01). Integration with gene expression datasets is still underway due to the limitations of annotating sheep genes. In addition, these metabolites are novel and have never been shown to modulate fat class in sheep. To elucidate methods of predicting which livestock produce ideal carcasses, further research is needed to investigate how betaine and choline impact fatness in sheep. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify small molecule metabolites in a serum sample taken at entry into the feedlot that can predict performance, and animal health. One-hundred and thirty-one Angus x Simmental steers from a single ranch were sampled at a commercial feedlot in Chappell, NE. Blood samples for metabolite analysis, chute score, exit velocity, and blood lactate concentration for temperament classification were collected in addition to feedlot performance data and carcass quality measurements. The GLM and LSM procedures of SAS (SAS 9.4, 2014) were used to evaluate differences between temperament classifications. Steers were divided into three exit velocity classifications one standard deviation from the mean were classified as fast and exit velocities lower than one standard deviation from the mean were slow. Forty metabolites were quantified using 1H NMR Spectroscopy from serum. Metaboloanalyst was used to analyze serum metabolites and phenotypic values using one way-ANOVA, PCA, PLS-DA, and a permutation test to cross validate. Data were normalized and scaled. No metabolites were predictive of any of the animal health metrics collected. Five metabolites were different in exit velocity class at (P < 0.01; Methanol, Isopropanol, Lactate, Isobutyrate, and Pyruvate). Similarly, seven metabolites were different in chute score classes at (P < 0.01) (Methanol, Isobutyrate, Creatinine, Dimethly Sulfone, Hippurate, Isopropanol, and Succinate). Furthermore, several metabolites in serum at entry in the feedlot were related to carcass quality metrics; Back Fat (Urea and 2-Hydroxyisobutyrate at (P < 0.01), a trend for prediction of quality grade at (P = 0.068), carcass value (P = 0.085). The relationship between serum metabolites identified on entry into the feedlot, feedlot performance traits, and eventual carcass quality warrants further research to elucidate the roles these metabolites play during the feedlot period and in predicting carcass merit. [ABSTRACT FROM AUTHOR]