Genetic and Phenotypic Parameters for Feed Efficiency Traits in Australian Angus Beef Cattle

Feed intake represents a major cost to all animal production systems. Increasing the efficiency in which animals turn this feed into product can be a major goal in many animal breeding programs. Consequently, Australian beef producers have been measuring many traits associated with feed efficiency in an attempt to increase the accuracy of selection, precision of genetic parameters estimates and ultimately increase the amount of genetic gain achieved. The objective of this study was to estimate genetic and phenotypic parameters for traits associated with feed efficiency from records on 1614 Angus Steers from the Australian Beef Information Nucleus (BIN). Traits analysed included Average Daily Weight Gain (ADG), Metabolic Mid-Weight (MMWT), Daily Feed Intake (FI), Feed Conversion Ratio (FCR) and Residual (or Net) Feed Intake (RFI). Parameters were estimated using bivariate animal models in ASReml. Heritability estimates ranged from 0.12 ±0.06 for FCR to 0.49 ±0.09 for FI. High genetic correlations were estimated between FI and RFI (0.83±0.05) and FI and ADG (0.81±0.08). Significant genetic correlation also existed between ADG and MMWT (0.65±0.12) and between MMWT and FI (0.68±0.08). Heritability estimates show that there would be a favourable response to selection for the efficiency traits in this population. The positive and unfavourable genetic correlation between ADG and RFI, suggest that improving RFI would result in lower ADG. Given this, further studies are required to investigate genetic associations between efficiency traits and other economically important traits, in addition to examine new ways of utilizing feed efficiency information in breeding programs.