## 2 Materials and Methods  
### Data Collection  
A total of 80 young bulls from northern German farms were processed under standard commercial conditions in a specialized cattle slaughterhouse (Boseler Goldschmaus, Niedersachsen, Germany). The experiment was conducted over four different working weeks during the summer months of 2022 (May to September). Average daytime temperatures between 7 and 25 \({}^{\circ}\)C were recorded throughout the experimental period. The slaughtering of the bulls exclusively occurred on Mondays and Tuesdays, spanning from 6:00 until 18:00 h. This operation involved the processing of 10 young bulls per working day, totaling 20 animals slaughtered within the course of a working week. Fleckvieh (Simmental) was the predominant breed in this study, representing 65% of the young bulls, followed by a cross of dairy \(\times\) meat breeds (28.75%), Holstein-Friesian (2.5%), and other local breeds (3.75%), as displayed in Table 1. The animals traveled between 9.9 km and 83.8 km to reach the slaughterhouse, with transport times between 20 min and 80 min. The slaughter weight of the animals was between 316 kg and 534 kg, and the slaughter age was between 16.2 and 24.3 months, as presented in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **\(\mathbf{n}\)** & **Frequency (\%)** \\ \hline \multicolumn{4}{c}{_Breed type_} \\
**Fleckvieh** & 52 & 65 \\
**Dairy \(\times\) meat cross** & 23 & 28.75 \\
**Holstein Friesian** & 2 & 2.5 \\
**Others** & 3 & 3.75 \\ \hline \multicolumn{4}{c}{_Conformation_} \\
**E** & 0 & 0 \\
**U** & 37 & 46.25 \\
**R** & 41 & 51.25 \\
**O** & 2 & 2.5 \\
**P** & 0 & 0 \\ \hline \multicolumn{4}{c}{_Carcess fat_} \\
**1** & 0 & 0 \\
**2** & 30 & 37.5 \\
**3** & 50 & 62.5 \\
**4** & 0 & 0 \\
**5** & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Carass conformation scores according to the EUROP system (E = very good and P = very poor), carcass fat scores (5 = very fat and 1 = very lean), and breed frequency for all cattle from the four different working weeks. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Item** & **Mean** & **SD** & **SE** & **Minimum** & **Maximum** \\ \hline \multicolumn{4}{c}{_Animals_} \\
**Age (months)** & 20 & 2 & 2 & 16 & 23.9 \\
**Weight (kg)** & 444.3 & 37.3 & 4.17 & 316 & 534 \\ \hline \multicolumn{4}{c}{_Transport conditions_} \\
**Distance (km)** & 45.3 & 19.6 & 2.19 & 9.9 & 83.8 \\
**Duration (min)** & 39 & & & 15 & 80 \\ \hline \multicolumn{4}{c}{_Air temperature at slaughter days(\({}^{\circ}\)C)_} \\
**Working week 1** & 10.75 & 4.57 & 2.29 & 8 & 16 \\
**Working week 2** & 17.25 & 4.99 & 2.5 & 13 & 24 \\
**Working week 3** & 18.75 & 5.19 & 2.59 & 14 & 25 \\
**Working week 4** & 10 & 2.45 & 1.22 & 7 & 12 \\ \hline \multicolumn{4}{c}{_Slaughterhouse_} \\
**Lairage time (min)** & 104 & & & 33 & 184 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Information regarding pre-mortem conditions in the weeks of slaughtering. Upon arrival at the slaughterhouse, animals from the same truck were moved, distributed, and kept in lairage for between 33 min and 184 min. This was conducted in separate pens to prevent mixing with strange cattle (Table 2). Then, the young bulls were slaughtered after being stunned using a captive bolt, suspended by a hind leg, and exsanguinated. Carcasses were later classified by a trained inspector according to hot carcass weight, as detailed in Table 2. Backfat thickness and conformation scores were also assessed, considering the EU classification system scores of 1, 2, 3, 4, and 5 to represent the degree of fatness (with 1 representing carcasses with the lowest fat content, and 5 the highest), and E-U-R-O-P conformation scores (with E being the best and P the poorest), as described in Table 1. Samples were then collected from the left side of the hanging carcass after 45 min post-mortem, which was the usual time that it took for an animal to be processed (from exsanguination until the carcass entered the cooling rooms).