Relationships between feed efficiency, growth and carcass traits in Japanese Black cattle

<p>The objectives of this study were to investigate the efficiency of measuring individual feed intake and to clarify the relationships between residual feed intake (RFI) and economic traits of fattening cattle in the field progeny test. The feed intake, body weight and carcass traits were obtained for the total of 480 Japanese Black steers (240) and heifers (240), and their RFI were calculated by their feed intake and body weight. Fattening period was separated early and late, and correlations between the periods and the whole fattening period were calculated to investigate their relationships. To clarify the relationships between RFI and economic traits, the RFI was divided into four quartiles and means of the traits were compared among the RFI quartile groups. In the correlations for RFI of each diet among fattening period, there were strong correlations between the late and whole fattening periods on concentrate and total feed intakes. This suggested that the RFI of the animals for the whole fattening period could estimate by the RFI based on concentrate feed intake in the late period. The daily TDN intake during the fattening period in the first (best) RFI group was 12% lower than that in the fourth (worst) RFI group. In steers, mean RFI in the first group was -0.921 kg/day which was 1.8 kg/day lesser than that in the fourth group, implying that animals with superior RFI can reduce the production cost for farmers. Means of growth and carcass traits in the first group were similar to the fourth group. These results suggest that feed intake in the field progeny test can measure efficiently and selection for the RFI from the test can reduce feed intake and improve productivity without affecting growth and carcass traits.</p>