Relationships among performance, residual feed intake, and product quality of progeny from Red Angus sires divergent for maintenance energy EPD

Energy expenditure is a physiological process that may be closely associated with residual feed intake (RFI). The maintenance energy (MEM) EPD was developed by the Red Angus Association of America (RAAA) and is used as an indicator of energy expenditure. The objectives of this study were to evaluate and quantify the following relationships using progeny of Red Angus (RA) sires divergent for MEM EPD: 1) postweaning RFI and finishing phase feed efficiency (FE), 2) postweaning RFI and end-product quality, and 3) postweaning RFI and sire MEM EPD. A total of 12 RA sires divergent for MEM EPD were chosen using the RAAA-generated MEM EPD values and were partitioned into 2 groups: high MEM EPD (>= 4 Mcal/mo) and low MEM EPD (<4 Mcal/mo), based on the breed average of 4 Mcal/mo. Commercial crossbred cows were inseminated to produce 3 cohorts of progeny, which were tested for postweaning RFI (cohorts 1, 2, and 3) and finishing phase FE (cohorts 1 and 3). Results indicate that postweaning RFI and finishing phase FE of steer progeny tended to be positively correlated (r = 0.38; P = 0.06) in cohort 1 and were positively correlated (r = 0.50; P = 0.001) in cohort 3. In addition, postweaning RFI was not phenotypically correlated (P > 0.05) with any carcass traits or end-product quality measurements. Sire MEM EPD was phenotypically correlated (P < 0.05) with carcass traits in cohort 1 (HCW, LM area, KPH, fat thickness, and yield grade) and cohort 2 (KPH and fat thickness). Since variation in measured LM area was not explained by the genetic potential of rib eye area EPD, and therefore, the observed correlation between sire MEM EPD and measured LM area may suggest an association between MEM EPD and LM area. A correlation (r = 0.24; P = 0.02) was observed between postweaning RFI and ultrasound intramuscular fat percentage in cohort 2 but was not detected in cohorts 1 or 3. In addition, no phenotypic relationship was observed (P > 0.05) between progeny postweaning RFI and sire MEM EPD. Therefore, results suggest 1) RFI measured during the postweaning growth phase is indicative of FE status in the finishing phase, 2) neither RFI nor sire MEM EPD negatively affected carcass or end-product quality, and 3) RFI and sire MEM EPD are not phenotypically associated.