Genetic relationships of measures of residual feed intake and daily feed intake with serum IGF-I concentrations at 8 wk of age and at 105 kg of BW, serum leptin concentration at 105 kg of BW, meat quality, and different fat accumulation traits on 834 Duroc pigs in 7 generations were estimated. Two measures of residual feed intake were estimated from the differences between actual and predicted ...

Providing feed is a major input cost in beef production, hence improvements in the efficiency of feed utilisation will reduce the cost of production. Residual feed intake (RFI) is a measure of feed efficiency, and is defined as the difference between an animal's actual feed intake and its expected feed intake based on its size and growth. It is independent of the level of production, and the lo...

The objective of this project was to investigate the effects of selecting sires for residual feed intake (RFI) on the performance of their daughters. Bulls with low or high estimated breeding values (EBV) for RFI were selected from the Angus Society of Australia sire summary and mated to Angus cross commercial cows at the Kansas State University Cow-Calf Unit in 2005 and 2006. The average EBV o...

The objective of this project was to investigate the effects of selecting sires for residual feed intake (RFI) on the performance of their daughters. Bulls with low or high estimated breeding values (EBV) for RFI were selected from the Angus Society of Australia sire summary and mated to Angus cross commercial cows at the Kansas State University Cow-Calf Unit in 2005 and 2006. The average EBV o...

Variation in residual feed intake, that is, variation in feed intake in relation to liveweight (LW) and growth rate, was investigated using data from 540 progeny of 154 British Hereford sires, collected over ten 200-day postweaning performance tests conducted between 1979 and 1988. Residual feed intake (RFI ) was calculated for each test as the difference between Reg actual feed and expected fe...

This study evaluated phenotypic (rph) and genetic correlations (rg) between 8 feed efficiency traits and other traits of economic interest including weight at selection (WS), loin-eye area (LEA), backfat thickness (BF), and rump fat thickness (RF) in Nellore cattle. Feed efficiency traits were gain:feed, residual feed intake (RFI), residual feed intake adjusted for backfat thickness (RFIb) and ...

Data on individual daily feed intake, BW at 28-d intervals, and carcass composition were obtained on 1,212 crossbred steers. Within-animal regressions of cumulative feed intake and BW on linear and quadratic days on feed were used to quantify initial and ending BW, average daily observed feed intake (OFI), and ADG over a 120-d finishing period. Feed intake was predicted (PFI) with 3 biological ...

Interest in improving feed efficiency in cattle is intensifying. Residual feed intake (RFI), which is the difference between expected intake and that predicted based on energy demands, is now the most commonly used measure of feed efficiency over a given time period. However, RFI, as commonly defined, is independent of growth rate, which may affect its acceptance by industry. Residual BW gain (...

Plasma urea nitrogen can be used as an indicator of N use and excretion by an animal. The objective of this research was to assess the effect of residual feed intake (RFI) on plasma concentration of urea N (PUN) in 188 bulls, heifers, and steers (mean body weight = 652 lb, SD = 82 lb) ranging from 100% Angus to 100% Brahman. Calves were assigned to pens in a GrowSafe feeding facility by sire gr...

Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between actual feed intake and expected feed intake required for maintenance and production. The objective of this study was to determine the relationship between RFI, feeding behavior, and other performance traits in growing heifers. Individual DMI was measured in Brangus heifers (n = 115) fed a roughage-based...