Project Number: 1265-31000-097-02
Project Type: Reimbursable

Start Date: Aug 08, 2007
End Date: May 31, 2010

Objective:
1. Identify metabolic phenotypes (metabolome) in economically important and service oriented tissues that characterize anabolic responses in steers when macronutrient supply is altered. 2. Identify metabolic pathway fluxes (fluxome) in economically important and service oriented tissues that characterize anabolic responses in steers when macronutrient supply is altered. 3. Identify coordinated genomic responses (transcriptome) in economically important and service oriented tissues that characterize anabolic responses in steers when macronutrient supply is altered. 4. Identify regulatory elements of the metabolome-fluxome-transcriptome networks that support partition of macronutrients towards protein accretion, fat accretion or catabolism.

Approach:
Characterize the mechanistic relationships between the expression of metabolism-related genes (transcriptome), the composition of substrate fluxes through macronutrient pathways (fluxome) and develop a metabolic phenotype (metabolome) for growing beef cattle. Three complimentary techniques will be employed simultaneously in beef cattle in vivo, namely a Bovine Metabolism-Related micro-array (BMET) coupled with real-time reverse transcription-polymerase chain reaction analyses, metabolomic (known substrate and metabolic-coupler concentrations) and fluxomic analyses. The fluxome profile will be determine from infusion of [U-13C]glucose followed by 13C-mass isotopomer distribution analysis (MIDA) to assess between and within tissue intermediate-substrate fluxes. To identify key rate-limiting metabolic elements affecting macronutrient utilization, groups of beef cattle (~300 kg) will be fed a forage-based diet and infused per abomasum with either water, casein or starch, or fed Na-propionate for 42-d.