Department of Animal and Veterinary Sciences, University of Idaho, Moscow, ID 83844, USA.
J Anim Sci. 2012 Dec;90(13):5107-17. doi: 10.2527/jas.2012-5184. Epub 2012 Aug 7.
Energy expenditure is a physiological process that may be closely associated with residual feed intake (RFI). The maintenance energy (ME(M)) 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 ME(M) EPD: 1) postweaning RFI and finishing phase feed efficiency (FE), 2) postweaning RFI and end-product quality, and 3) postweaning RFI and sire ME(M) EPD. A total of 12 RA sires divergent for ME(M) EPD were chosen using the RAAA-generated ME(M) EPD values and were partitioned into 2 groups: high ME(M) EPD (≥4 Mcal/mo) and low ME(M) 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 ME(M) 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 ME(M) EPD and measured LM area may suggest an association between ME(M) 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 ME(M) 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 ME(M) EPD negatively affected carcass or end-product quality, and 3) RFI and sire ME(M) EPD are not phenotypically associated.
能量消耗是一个可能与剩余采食量（RFI）密切相关的生理过程。维持能量（ME（M））EPD 由美国红安格斯协会（RAAA）开发，用作能量消耗的指标。本研究的目的是使用 ME（M）EPD 差异较大的红安格斯（RA）种公牛后代来评估和量化以下关系：1）断奶后 RFI 和育肥阶段饲料效率（FE），2）断奶后 RFI 和终产品质量，3）断奶后 RFI 和种公牛 ME（M）EPD。选择了 12 头 ME（M）EPD 差异较大的 RA 种公牛，这些种公牛是根据 RAAA 生成的 ME（M）EPD 值，并根据品种平均值 4 Mcal/mo 分为 2 组：高 ME（M）EPD（≥4 Mcal/mo）和低 ME（M）EPD（<4 Mcal/mo）。商业杂交奶牛被人工授精以产生 3 组后代，这些后代接受了断奶后 RFI（组 1、2 和 3）和育肥阶段 FE（组 1 和 3）的测试。结果表明，在组 1 中，公牛后代的断奶后 RFI 和育肥阶段 FE 呈正相关（r=0.38；P=0.06），在组 3 中呈正相关（r=0.50；P=0.001）。此外，断奶后 RFI 与任何胴体性状或终产品质量测量值均无表型相关性（P>0.05）。在组 1（HCW、LM 面积、KPH、脂肪厚度和产肉等级）和组 2（KPH 和脂肪厚度）中，种公牛 ME（M）EPD 与胴体性状呈表型相关性（P<0.05）。由于测量的 LM 面积的变化不能用眼肌面积 EPD 的遗传潜力来解释，因此，观察到的种公牛 ME（M）EPD 和测量的 LM 面积之间的相关性可能表明 ME（M）EPD 和 LM 面积之间存在关联。在组 2 中观察到断奶后 RFI 与超声肌肉内脂肪百分比之间的相关性（r=0.24；P=0.02），但在组 1 和 3 中未检测到。此外，在后代断奶后 RFI 与种公牛 ME（M）EPD 之间未观察到表型关系（P>0.05）。因此，结果表明 1）断奶后生长阶段测量的 RFI 表明育肥阶段的 FE 状态，2）RFI 和种公牛 ME（M）EPD 均不影响胴体或终产品质量，3）RFI 和种公牛 ME（M）EPD 之间无表型关联。
