Response to selection in beef cattle using IGF-1 as a selection criterion for residual feed intake under different Australian breeding objectives

In this study various scenarios of selection in beef cattle using the physiological marker insulin-like growth factor (IGF-1) were investigated. Previous research shows that IGF-1 has favourable correlations with a number of important traits in beef cattle including residual feed intake (RFI), carcass fatness, average daily gain, live weight and carcass weight. The aim of this study was to compare the genetic response and profit to varying selection strategies that used direct selection for RFI and indirect selection with IGF-1 in association with other traits. Two breeding objectives for Australian producers were assessed relating to the high value Japanese export market, of which marbling is paid a premium, and the Australian domestic market. Selection for IGF-1 proved profitable in all scenarios for an export objective with the most optimal use as a first-stage selection tool before a feed intake trial for young bulls. Benefits of selection for IGF-1 with the domestic objective were similar to the export objective but increases in profit were marginal when used without feed intake information.