Relationship between feed intake, feeding behaviors, performance, and ultrasound carcass measurements in growing purebred Angus and Hereford bulls

摘要: The objectives of this study were to examine the growth, DMI, and feeding behaviors Angus Hereford bulls; identify relationships between variation in DMI residual feed intake (RFI); determine value predicting DMI. Individual was measured bulls (n=189; initial BW=427±3.4 kg) (n=146; BW=411±4.1 fed a grower ration for 71 d 2009, 78 2010, 74 2011 using GrowSafe monitoring system. Feeding frequency (FF, meals/d), head down duration (HDD, s/d), per meal (HDDM, HDD/FF, s/meal), average size [AMS, kg/(meal·d)], rate (FR, g/s) also or calculated behavior data collected by Ultrasound measures 12th-rib fat thickness (UFT), longissimus muscle area (ULMA), intramuscular (IMF) determined during midtest-weight event every trial. from 3 yr pooled generate mean differences breeds. Residual linear regression on ADG midtest BW0.75 (MMWT). Animals classified into RFI groups based their score as Low (>0.5 SD below mean), Average (±0.5 High above mean). group consumed 17% (P<0.0001) less DM than group, while there 14% difference groups. Significant phenotypic correlations observed (0.83, 0.77), G:F (-0.65, -0.51), HDD (0.41, 0.59), HDDM (0.40, 0.53), AMS (0.52, 0.36), FR (-0.31, -0.51) bulls, respectively. HDD, HDDM, significantly correlated with traits, when added base model, explained 18, 17, 13%, respectively, not MMWT bulls. Similarly, 35, 26, 24%, MMWT. These suggest that are related growing