Body composition and implications for heat production of Angus steer progeny of parents selected for and against residual feed intake
TLDR
There was no evidence that a difference in the chemical composition of gain over the test explained the greater intake of metabolisable energy (ME) by the high RFI steers, and the results suggest that the difference in ME intake following a single generation of divergent selection for RFI was due to metabolic processes rather than to changes in body composition.Abstract:
Yearling Angus steer progeny of parents selected for low residual feed intake (RFI; high efficiency) or high RFI (low efficiency) were evaluated for feed intake, growth and differences in body composition. RFI is the difference between actual feed intake and expected feed intake based on an animal’s size and growth over a test period. Individual intakes of a high grain content ration and growth rates were recorded for 140 days and then the steers were slaughtered for measurement of body composition. All internal organs and non-carcass fat depots were removed, weighed and ground for chemical analysis. Carcasses were kept overnight in the chiller and the left half of every carcass physically dissected into retail cuts, and then into total fat, lean and bone. Carcass fat and lean were then combined and ground for chemical analysis. Steers from low RFI parents ate less (P<0.05) than the steers from high RFI parents, for similar rates of growth. Improvement in RFI was accompanied by small changes in body composition towards greater lean and less fat in the progeny of low RFI parents. Correlations of sire estimated breeding values for RFI with end of test whole body chemical protein, chemical fat and a principal component that condensed information on fat and lean body composition at the end of the test, were statistically significant. These confirmed there was a genetic association between body composition and RFI, with fatness being associated with higher RFI (i.e. lower efficiency). However, the correlations were small and suggested that less than 5% of the variation in sire RFI was explained by variation in body composition of their steer progeny. There was no evidence that a difference in the chemical composition of gain over the test explained the greater intake of metabolisable energy (ME) by the high RFI steers. The results suggest that the difference in ME intake following a single generation of divergent selection for RFI was due to metabolic processes rather than to changes in body composition.read more
Citations
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Journal ArticleDOI
Residual feed intake and body composition in young growing cattle
TL;DR: Crossbred steers from the five BeefBooster strains were used to determine the relationships between residual feed intake and growth rate, body composition and heat production, and to quantify differences in RFI independent of differences in body composition.
Journal ArticleDOI
Physiological basis for residual feed intake.
R. M. Herd,P. F. Arthur +1 more
TL;DR: Residual feed intake is a measure of feed efficiency that is independent of level of production, such as size and growth rate in beef cattle, and thus is a useful new trait for studying the physiological mechanisms underlying variation in feed efficiency.
Journal ArticleDOI
Effect of divergence in residual feed intake on feeding behavior, blood metabolic variables, and body composition traits in growing beef heifers.
TL;DR: The feeding behavior traits of eating rate, daily feeding events, and nonfeeding events were positively correlated (P < 0.05) with RFI and RFI(c).
Journal ArticleDOI
Different measures of energetic efficiency and their phenotypic relationships with growth, feed intake, and ultrasound and carcass merit in hybrid cattle.
J. D. Nkrumah,John A. Basarab,M. A. Price,Erasmus Okine,A. Ammoura,S. Guercio,C. Hansen,Changxi Li,B. Benkel,Brenda M. Murdoch,Stephen S. Moore +10 more
TL;DR: These phenotypic relationships indicate that, compared with other measures of energetic efficiency, RFI should have a greater potential to improve overall production efficiency and PEG above maintenance, and lead to minimal correlated changes in carcass merit without altering the growth and body size of different animals.
Journal ArticleDOI
Genetic and phenotypic relationships of feed intake and measures of efficiency with growth and carcass merit of beef cattle.
J. D. Nkrumah,John A. Basarab,Zhiquan Wang,Changxi Li,Changxi Li,M. A. Price,Erasmus Okine,D. H. Crews,Stephen S. Moore +8 more
TL;DR: Depending on how RFI technology is applied, adjustment for body composition in addition to growth may be required to minimize the potential for correlated responses to selection in cattle.
References
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