Recipient Organization
AUBURN UNIVERSITY
108 M. WHITE SMITH HALL
AUBURN,AL 36849
Performing Department
ANIMAL SCIENCES
Non Technical Summary
Efficiency of performance is paramount for the continued profitability and sustainability of the US Beef Cattle Industry. In the past, production efficiency has been evaluated by relating performance to output, typically total or rate of weight gain. However the fastest gaining animals are not necessarily the most efficient since they may exhibit high maintenance costs. It has been shown that feed efficiency (FE) and a related measure, residual feed efficiency (RFI) are more highly related to efficiency of performance and would be useful as more robust selection criteria in breeding programs. Unfortunately FE and RFI can only be determined by a long term feeding trial for each individual animal. Thus determinations of FE and RFI is cost prohibitive and hence the use of these efficiency parameters in breeding programs by the commercial beef cattle industry is severely limited. The purpose of this project is to develop a process, based on expression of genes related to
performance efficiency in fat and muscle tissues of cattle, that can reliably predict which animals will have better FE and RFI. It has already been shown that FE and RFI in cattle are moderately heritable and amenable to selection and improvement via well designed breeding programs. The use of expression patterns of specific efficiency marker genes measured while animals are still young, can then be utilized as more robust selection tools for superior bulls and females and subsequent mating strategies.
Animal Health Component
10%
Research Effort Categories
Basic
80%
Applied
10%
Developmental
10%
Goals / Objectives
The objective of this one year study is to test the hypothesis that in cross bred beef cattle expression of patterns of genes involved in oxidative metabolism, lipid anabolism and protein turnover will be related to variations in feed efficiency among similar sized animals in the late growing phase.
Project Methods
At the Alabama Agricultural Experiment Station Black-Belt Substation a cattle breeding /selection program was initiated to develop strategies to select cattle for residual feed efficiency (RFI). Progeny of matings of sires and dams selected for higher and lower potential RFI (16 total cross bred cattle) after weaning at 325 Kg will be assigned to a 84 day feeding trial; daily feed intake and weight gain will be measured. On day 42, tissue biopsies will be secured (September, 2006) from tail head adipose depots and from loin muscle. All tissues will be powdered cryogenically and RNA will be isolated using the Trizol procedure. Harvested RNA will then be purified and gene expression will be accomplished with quantitative RT-PCR using a 2 step (RT first) approach. M-RNA abundance will be determined for the following genes in 1) skeletal muscle: PPAR α, cyto-C oxidase, CPT-1, ubiquitin conjugating enzymes E2, ubiquitin specific protease, UCP2 and 3; in 2) adipose
tissue: PPARγ2, fatty acid synthase, leptin, GPAT, UCP 2 and 3 and PCG-1α. From the feeding trial, the RFI for each animal will be determined; the gene expression results for each animal will then be related to RFI with appropriate regression and statistical procedures to test for the significance of correlation between RFI and fatty acid oxidation, synthesis, mitochondrial efficiency and protein turnover.