Project 13-reanalysis of Project 6 and Beef CRC 1 and 2 data for SNPs

Summary

The objectives of this project were:
A. To determine whether associations with NFI or other measures of efficiency of feed utilization that are observed from appropriate analyses, are significantly different from what would be expected by random chance given the nature and number of analyses performed
B. If the conclusion in A, is that results do deviate from random chance, determine what confidence can be placed on the estimates of individual or combined marker effects; and,
C. Given the results in B, determine what inferences can me made about an appropriate number of markers to include in a commercial test.
CONCLUSIONS
This study aimed to address an observed problem with the currently accepted measure of feed efficiency (net feed intake). As currently defined, net feed intake is genetically and phenotypically related to lower daily feed intakes and is not correlated with growth rates. While this may reduce daily feedlot costs, if used as a single measure of the value of an animal to feedlots it may not increase overall profitability. Therefore other measures were investigated but they were either highly correlated with the existing NFI trait (e.g. NFIP8) or were lowly heritable (e.g. FCR and TFI35). Therefore this work has not identified a suitable alternative genetic measure for NFI for feedlot feed efficiency. Therefore to use the existing NFI measure as a selection criteria to increase total profitability it should be used in conjunction with other traits such as growth (e.g. 600d wt EBV) or average daily gain, and also possibly marbling (e.g. IMF% EBV).