Slaughter Traits and Meat Quality Changes in Fattened Bulls Among Different Xinjiang Brown Cattle Beef-Types
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ABSTRACT Background: The Xinjiang Brown cattle beef-types (XBC-Beef-Type) were developed through graded crossing of Xinjiang Brown cattle (XBC) with Canadian Braunvieh bulls across different generations, followed by inter se mating and fixation. While previous studies have documented the growth performance of F1 hybrids, systematic comparisons of carcass traits and meat quality across three generations (Type I, II, and III) under standardized feedlot conditions are lacking. Moreover, the impact of graded Canadian Braunvieh introgression on muscle fiber characteristics and fibre type composition, and their relationship to meat tenderness remain poorly understood. Methods: Twenty-four bulls (24 ± 3 months of age) were allocated to four groups (n = 6 per group): purebred XBC (Ctrl), XBC-Beef-Type I (F1 inter se), XBC-Beef-Type II (F2 backcross inter se), and XBC-Beef-Type III (F3 backcross inter se). After a 14-day adaptation period in a common pen, bulls were housed in four separate open pens (one pen per group, 6 bulls/pen, ~20 m² per bull) for 180 days of finishing. A total mixed ration was offered ad libitum three times daily. Body size, slaughter performance, meat quality traits, and muscle fiber histology were compared among groups. Results: Type III exhibited 9.4% greater body diagonal length (185.3 vs. 169.3 cm, P < 0.01), 5.4% larger chest girth (217.2 vs. 206.0 cm, P < 0.05), and 14.0% greater cannon girth (24.5 vs. 21.5 cm, P < 0.05) than Ctrl. Body weight increased by 10.9–13.4% (P < 0.01) and carcass weight by 12.6–15.5% (P < 0.01) across Type I–III. Type III showed a 7.8% larger loin-eye area (111.9 vs. 103.8 cm², P < 0.05), 23.5% higher IMF in supraspinatus (P < 0.01), 18.2% lower shear force across all muscles (P < 0.05), and elevated WHC (P < 0.05). Histologically, Type III displayed smaller fibre diameters (P < 0.05) and a muscle-specific shift toward oxidative phenotypes—higher Type I and IIa proportions in supraspinatus and semitendinosus (P < 0.05–0.01), and selective IIa increase in longissimus dorsi (P < 0.01). Conclusions: Graded introgression of Canadian Braunvieh genetics progressively improved growth performance, carcass traits, and meat quality in Xinjiang Brown cattle. Type III demonstrated the most favorable combination of these traits, including a muscle-specific shift toward oxidative fibre types and reduced fibre diameter, supporting its recognition and promotion as a specialized beef-type variety for local production systems. Keywords: Xinjiang Brown cattle; Canadian Braunvieh; carcass yield; intramuscular fat; muscle fibre histology, Fibre type composition
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1. Data were collected from 24 fattened bulls (6 per group) at a commercial feedlot in Ili Prefecture, Xinjiang, China. 2. Body size measurements followed ICAR guidelines. 3. Slaughter and carcass evaluation were conducted at a commercial abattoir. 4. Meat quality traits (IMF, WBSF, WHC, cooking loss, pH, colour) were measured according to standard protocols. 5. Muscle fiber histology (H&E staining) and fiber typing (NADH-TR staining) were performed on paraffin and frozen sections, respectively. 6. Statistical analysis was performed using one-way ANOVA followed by Dunnett's post-hoc test in GraphPad Prism 10. 7. Raw data are provided in separate sheets for each measurement category.