A shift in selection goals for beef production has taken place with more emphasis being placed on efficient production. The reduction in feed costs, being the largest expense in beef production, may hold possibilities for increasing profitability. Various traits have been developed in the past with the aim of selecting for increased feed efficiency, it is, however, important to take into consideration the impact that selection for one trait might have on other traits throughout the production cycle. The aim of this study was to estimate genetic parameters for feedlot traits for the South African Angus and Simmental beef breeds, with specific emphasis on net feed intake (NFI) as means of selection for feed efficiency. Genetic parameters for various feedlot traits as well as body measurements were estimated, with special focus on the relationship that exists amongst these traits. Net feed intake (NFI) was used as an alternative for feed efficiency (feed conversion rate (FCR) was previously the most commonly used trait in South Africa as means of improving feed efficiency). FCR, however, has an unfavourably strong relationship with average daily gain (ADG), which in turn can lead to the selection of animals with higher mature weights. NFI is phenotypically independent of growth and body weight and should address the antagonism that exists with FCR. The results indicate a weak associations between NFI and body weight and growth traits, implying that NFI should have little effect on these and other related traits. This is in contrast to the moderate to strong correlations of FCR with the same traits. There is a significant difference in the strength of the correlations found for the above-mentioned feed efficiency traits with growth and body weight traits. If the aim is thus to improve feed efficiency without affecting the size of the breeding herd, NFI should be used as an alternative trait for feed efficiency. Keywords: net feed intake, feed conversion ratio, Angus, Simmental

Jurgen Hendriks, M. M Scholtz, J. B Van Wyk, F. WC Neser

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Biology - Feed Intake and Efficiency 1, , 507, 2018
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