PSIII-15 Use of Ultrasound Technology to Estimate Final Carcass Composition in Harvested Beefmaster Steers

Abstract

Abstract The objective of this research study was to determine the accuracy of ultrasound scanning to predict post-harvest carcass data. Beefmaster steers (n = 47) representing two different sires were ultrasounded 62 d before harvest using an Aloka 500 ultrasound unit, equipped with a 17.2cm probe to collect 12th rib fat thickness (FTU), 12th rib longissimus muscle area (LMAU), intramuscular fat (%FatU) and rumpfat (RFU). Beef Image Analysis (BIA) software was used to determine FTU, REAU, %FatU and RFU using chuteside captured ultrasound images on all steers. Carcass data collection included 12th rib fat thickness (FTC), 12th rib longissimus muscle area (REAC) and marbling score (MS). Additionally, Warner-Bratzler shear force (WBSF) and ether extraction (EE) estimates were determined on 12 to 13th longissimus muscle samples. All carcass data were collected by the Beef Carcass Research Center at West Texas A&M University. Data were analyzed using SAS version 9.4. Simple descriptive statistics were 1.03 ± 0.25 cm, 90.1 ± 8.64 cm2, 457.3 ± 74.7, 1.35 ± 0.38, 5.75 ± 1.83, 3.86 ± .64 kg for FTU, REAU, %FatU, RFU, EE and WBSF, respectively. Simple descriptive statistics were 18 ± 0.35 cm, 89.72 ± 7.74 cm2, and 504.7 ± 67.2 for FTC, REAC and MS, respectively. Pearson correlation coefficients were 0.72 (P < 0.0001) between FTU and FTC, 0.52 (P < 0.0002) between REAU and REAC, and 0.45 (P < 0.0017) between %FatU and MS. Pearson correlation coefficients were 0.45 (P < 0.0017) between EE and %FatU and 0.72 (P < 0.0001) between EE and MS. These results suggest that ultrasound measures of final body composition should be taken closer to the final harvest date to better estimate endpoints of fat thickness, longissimus muscle area and intramuscular fat in harvest ready beef cattle.