Evaluation of marbling traits by X-ray computed tomography in Hungarian Simmental bulls

Abstract

Marbling is an economically important factor in many beef carcass grading schemes. This study aimed to evaluate marbling traits of longissimus thoracis muscle (LT) with different methods: USDA marbling score, intramuscular fat (IMF) content by image analysis of X-ray computed tomography (CT) scans and by conventional analytical method. Bulls (n=46) were slaughtered at an average weight of 536 kg and an average age of 646 days. Mean values of EUROP fat scores varied from 2− to 2+, whereas mean values of EUROP conformation grade from O0 to R0. Average growth rate of bulls was 955 g/day. Average chemical fat content of LT varied from 2.2% to 3.1% across conformation classes, and from 2.3% to 5.0% across fat classes. Intramuscular fat content in the 12th rib and in LT on CT-scans closely correlated with chemical fat content (r=0.81 and 0.85, respectively). The highest frequency of USDA marbling score was ‘small’ (55.2%), followed by ‘slight’ (25.5%), ‘modest’ (17%) and ‘moderate’ (2.1%). Computed tomography scans of LT can be used for the evaluation of marbling in Hungarian Simmental cattle. Bulls with higher growth rate had lower marbling level in LT (r=−0.4 to −0.5). EUROP conformation and fat scores have no relationship with marbling traits in this specific cattle population.