Abstract
Simple SummaryNowadays, in beef cattle breeding programs considerable interest lies in selecting animals that require fewer feed inputs without negatively impacting performance traits, thereby improving the profitability. This study has shown that the feeding behavior of Charolaise candidate young bulls mainly depend on residual feed intake (RFI), whilst RFI had no effect on phenotypic body composition and performance test results (except for feed intake/dry matter intake and gain to feed). Skeletal traits, including back-loin length and rump length as well as frame and muzzle width showed negative associations with RFI value, indicating that the longer, taller, higher frame size bulls were more efficient. At the same time, bulls with better RFI values were associated with forelegs/hind legs weakness. The close relationship of dry matter intake and feed efficiency in Charolaise candidate bulls suggests that measures are relevant and may have an application in the performance test. Performance from individual dry matter intake information may be the most cost-effective way to test a greater number of animals annually.This study evaluated the effect of differences in residual feed intake (RFI) of Charolaise candidate young bulls on feeding behavior and self-performance test results. Bulls were classified into high and low RFI (H-RFI, L-RFI) groups. Bulls were fed in a HOKOFARM system to measure individual animal intake and behavior. L-RFI bulls had significantly lower feed intakes (p = 0.002) and higher gain to feed ratio (p = 0.001), lower intake per day/kg DM (dry matter) (p = 0.002) and lower intake g/body weight/day (p < 0.001). L-RFI animals had lower visits number per day (p = 0.02), but spent longer time per visit (p = 0.02), and tended to have higher intake g/visit (p = 0.06) on feeders. The correlation between RFI and DMI (dry matter intake)/bodyweight/day as well as intake per day/kg were large and positive. Back-loin length and rump length, and moreover muzzle width and frame, showed negative correlations with RFI value. However, bulls with better RFI values associated with lower legs score. Results reveal that RFI was shown beneficial correlations with economically relevant self-performance traits. Further investigations are needed to seek additional indicator traits that are predictive for RFI.
Highlights
Recent increases in the costs of feeds have inspired considerable interest in the use of genetic selection strategies to improve feed efficiency in beef cattle [1]
We observed that residual feed intake of bulls belonging to high RFI group had value of 1.4, but low RFI group had −0.46 (p = 0.000)
The longissimus muscle area (LMA) was greater, but rump fat thickness (RFT) was lower in H-RFI animals by 6.8 cm2 and 0.5 mm, respectively
Summary
Recent increases in the costs of feeds have inspired considerable interest in the use of genetic selection strategies to improve feed efficiency in beef cattle [1]. Breeding programs that can produce animals that require fewer feed inputs without negatively impacting performance traits will improve the profitability of beef cattle production systems [2,3,4]. Residual feed intake (RFI) has been evaluated as an alternative trait for use in selection programs to improve feed efficiency [5,6]. Residual feed intake is calculated using a regression equation involving metabolic body weight and average daily gain, where a more efficient animal will have a negative or low RFI, indicating they consume less than predicted [8]. Different statistical approaches were found in literature, so the results are not comparable [12]
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