There is increasing evidence for the suitability of circulating plasma insulin-like growth factorI concentrations (IGF-I) as genetic predictors of some economically important traits in beef cattle (Herd et al. 1995, Davis and Simmen 2000, Johnston et al. 2001). This has lead to the suggestion that IGF-I might also be used as an indirect selection criterion for improving feed efficiency in cattle, particularly given the results from pigs (Bunter et al. 2002). Measures of feed efficiency, such as residual feed intake or feed conversion ratio, are heritable in beef cattle (Arthur et al. 2001), but expensive to measure making widespread industry recording of the trait unlikely. Therefore to improve feed efficiency across a breed or industry we need correlated trait(s) that can be easily measured on large numbers of cattle prior to the time when the major selection decisions are made. Records on IGF-I could be supplemented in a genetic evaluation with actual feed intake records collected on a subset of elite young animals or their progeny. Therefore the objective of this study was to estimate the genetic correlations between IGF-I and feed intake and efficiency traits.  

D. J Johnston, R. M Herd, M. J Kadel, H. U Graser, Paul F Arthur, J. A Archer

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 10, , 10.16, 2002
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