Potential for selection to improve efficiency of feed use in beef cattle: a review

Abstract

Evidence for genetic variation in feed efficiency of beef cattle is reviewed in this paper, and ways in which this variation might be used in selection programs to improve beef cattle in Australia are discussed. Efficiency of beef production systems is determined by feed and other inputs of all classes of animals in the production system as well as outputs in terms of slaughter progeny and cull cows. Different indices have been used to express aspects of efficiency on cattle over certain periods of the production cycle. Use of these indices is discussed, and then evidence for genetic variation in both growing animals and mature animals is reviewed. Genetic variation in feed efficiency exists in both growing and mature cattle, although information is lacking to determine whether variation in total production system efficiency exists. The physiological basis for observed variation in feed efficiency is discussed, with differences in requirements for maintenance, body composition, proportions of visceral organs, level of physical activity, and digestion efficiency identified as possible sources of variation. Selection to improve efficiency might be achieved by measuring feed intake of growing animals and utilising genetic correlations that are likely to exist between efficiency of growing animals and mature animals. Measurement of feed intake might occur in central test stations, or methods may be developed to measure feed intake on-farm. Ways of utilising information generated in genetic evaluations are discussed, and it is concluded that estimated breeding values for feed intake after a phenotypic adjustment for growth performance would be most practical, although not theoretically optimal. Such estimated breeding values would best be used in an economic selection index to account for genetic correlations with other traits, including feed intake of the breeding herd, and the economic value of feed in relation to other traits. Future research should be directed towards understanding the genetic relationships between feed intake and other traits in the breeding objective, and to find ways to reduce the cost of measurement of feed intake, including a search for genetic markers.

Residual feed intake of Angus beef cattle divergently selected for feed conversion ratio

“…Results of this study are in agreement with those of Archer et al (1999) and Arthur et al (2001b) that genetic variation exists among individual animals for RFI. On average, high RFI P bulls consumed 17.3% more feed than low RFI P bulls, a value that agrees very well with the 18% difference in the Brangus heifer data analyzed by Lancaster et al (2009).…”

Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 3. Feed efficiency and feeding behaviour of feedlot-finished animals

“…The literature generally agrees that genetic variation in feed efficiency exists (review by Archer et al 1999). These variations in feed efficiency potentially represent an opportunity for beef producers to significantly reduce production costs by reducing feed intake while maintaining growth rate.…”

“…A review by concluded that differences in efficiency of maintenance exist between breeds, and these differences are correlated with differences in productive potential of breeds. Efficiency of feed utilisation has several variable components including feed intake, digestion of feed, metabolism (including variation in body composition), activity and thermoregulation (reviews by Archer et al 1999;Herd et al 2004). Early research on tropically adapted genotypes (Vercoe 1967(Vercoe , 1970Vercoe 1969, 1977;Vercoe et al 1972) shows there are differences in feed intake, eating rate, weight gain, metabolic rate and efficiency of feed utilisation between breeds and across different environments.…”

Genetics of steer daily and residual feed intake in two tropical beef genotypes, and relationships among intake, body composition, growth and other post-weaning measures

“…The lower RFI suggests a greater efficiency of feed use for BRAH for the same MWT and TADG, which is in contrast with the higher observed feed conversion ratio for BRAH. RFI and feed conversion ratio are quite different traits (Archer et al 1999); Robinson and Oddy (2004) and Arthur et al (2001) found the correlation to be 0.66 in Angus. In the feed conversion ratio trait, there is no consideration of the feed required to maintain liveweight.…”

“…on genetic and phenotypic correlations, variances and means for live steer production traits including, as a particular focus, individual daily (DFI) and residual (RFI) feed intake. RFI is a measure of the efficiency of feed use that is being actively researched for use in genetic evaluation (Archer et al 1999;Arthur et al 2004;Herd et al 2003). A further aim was to evaluate the potential of measures, including insulin-like growth factor-I concentration (IGF-I), as genetic indicators of RFI.…”