Genetic parameters for live animal ultrasound measures, scrotal circumference, carcass and growth traits in Aberdeen Angus


  • Zdenka Vesela Institut of Animal Science, Prague
  • Alena Birovas
  • Michaela Brzakova
  • Alexandra Novotna
  • Lubos Vostry


Genetic parameters were estimated for body weight at scanning (SCW), scrotal circumference (SC), rump fat thickness (P8FT), rib fat thickness (RBFT), eye muscle area (EMA), intramuscular fat content (IMF), carcass weight (CW), carcass conformation (CC), carcass fatness (CF), adjusted weaning weight (AWW) and adjusted yearling weight (AYW) in the Czech Aberdeen Angus. Live ultrasound measures were collected on 1,949 animals and SC on 1,021 bulls aged 250 to 500 days through 2019, 2020, and 2022. Furthermore, there were 7,672 animals with carcass EUROP classification from commercial abattoirs, 36,958 animals with AWW and 15,572 with AYW collected since 2006. The fixed effect of contemporary group, sex*twin, age of the animal (for ultrasound, SC and carcass traits), age of dam (for ultrasound traits, SC, AWW, and AYW), and heterosis (for carcass traits, AWW and AYW) were included in the model equation. Random effects considered were the direct additive genetic effect and the residual effect. Heritability estimates for SCW, SC, P8FT, RBFT, EMA, IMF, CW, CC, CF, AWW and AYW were 0.69, 0.77, 0.49, 0.44, 0.71, 0.25, 0.57, 0.37, 0.33, 0.45 and 0.38 respectively. As expected, strong genetic correlations were estimated between SCW, CW, AWW, and AYW (0.55-0.99). Genetic correlations between ultrasound and carcass traits were moderate to high. The highest genetic correlations were estimated between P8FT (resp. RBFT) and CF (0.99). The genetic correlation between EMA and CC was 0.98, and between IMF and CF 0.60. Genetic correlations between SC and ultrasound traits were low to moderate (0.19-0.60), and between SC and carcass traits were high (0.85-0.97). Genetic correlations between carcass and growth traits were low (0.09-0.27), and between ultrasound and growth traits were low to moderate (-0.51-0.47). The results show a negative genetic correlation between IMF and CW (-0.17) and between IMF and AWW (-0.51), which indicates that selection on high AWW could lead to lower IMF in the Aberdeen Angus. The results support the potential value of live animal ultrasound measurements in the Czech Aberdeen Angus breeding program to generate indicator traits for carcass quality.