## 2 Materials and Methods
### Procedures for Slaughter and Muscle Sampling  
After refrigeration for 24 h at 4 \({}^{\circ}\)C, in the slaughterhouse, the carcass were weighed and cut into halves along the midline. At the slaughterhouse, the pH values were measured in the _longissimus lumborum_ muscle at the 4 th-5 th lumbar vertebra on the left side of the carcass, using a pH meter (Crison 507; Crison Instruments, Barcelona, Spain) equipped with a penetrating glass electrode. Buffer solutions between 4.01 and 7.0 were used to calibrate the pH meter (Crison Instrument S.A. 08328 Allea, Spain) and temperature compensation was controlled during the test.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{5}{c}{**Chemical Composition (\%, DM Basis)**} \\ \cline{2-6}  & **DM** & **Raw Protein** & **Raw Fibre** & **Ether Extract** & **Ash** \\ \hline \hline \multicolumn{1}{c}{Oat grain} & 88.95 & 10.40 & 12.13 & 3.92 & 2.86 \\ \hline \hline \multicolumn{1}{c}{Wheat grain} & 88.64 & 9.38 & 2.00 & 2.00 & 1.35 \\ \hline \hline \multicolumn{1}{c}{Concentrate supplement 1  } & 87.78 & 17.00 & 7.35 & 3.82 & 2.51 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main supplementary feeds during fattening period and their chemical composition in Mallorquina and Roja Mallorquina lambs.  
After the carcasses were chilled, the left halves of the carcasses were taken to the laboratory where the longissimus _thoraxis-lumborum_ (LTL) muscle was extracted and sliced. The proximate composition of LTL muscle was measured according to standard AOAC procedures [11] and expressed on a wet basis: the moisture content by procedure 24003, the nitrogen content by procedure 2057, the intramuscular fat content by procedure 13032, and the ash content by procedure 14066.  
At 48 h post-mortem, the colour of the LTL was evaluated after one hour of blooming using a Konica-Minolta CM colorimeter (Konica Minolta Inc., Tokyo, Japan) in the CIELAB color space [12] with a standard D65 illuminant, observed angle of 10\({}^{\circ}\), and zero and white calibration. The average of the three different measurements taken on the same surface (between lumbar and thoracic regions) were obtained. The lightness (L*), redness (a*) and yellowness (b*) were recorded. The Hue angle (H*) was calculated as tan\({}^{-1}\)(b*/a*) and the chroma (C*) as [(a*\({}^{2}\) + b*\({}^{2}\))\({}^{1/2}\)]. Two portions of LTL muscle (5 g each) were used to determine the water-holding capacity (WHC) of the meat according to [PERSON] et al. [13] using the pressure method. The WHC was expressed as the percentage of juice expelled after compression. A portion of 10 g from the LTL muscle was used to calculate the haem pigment concentration using a physical-chemical method expressed as mg myoglobin/g fresh meat [14]. The rest of the LTL muscle was vacuum-packed into three packages and frozen at \(-20\)\({}^{\circ}\)C before measuring the Warner-Bratzler shear force (WBSF), fatty acid profile and volatile compounds.  
To determine the WBSF, a vacuum-packed sample of LTL was thawed overnight at 4 \({}^{\circ}\)C. The sample, including a portion of caudal slices of LTL, was heated in a 75 \({}^{\circ}\)C water bath to an internal temperature of 70 \({}^{\circ}\)C. The temperature was monitored with a Jenway thermocouple equipped with a probe (Hanna Instruments HI 8757; 20600 Eibar, Gipuzkoa, Spain), and a Stevens QTS 25 texture analyser equipped with a WB device [13] was used. The LTL muscle was cut into slices with a cross-section of 1 cm\({}^{2}\) parallel to the muscle fibres. The maximum shear force (kg/cm\({}^{2}\)) was assessed in at least three subsamples of heated meat pieces parallel to the muscle fibres. Analyses were run in duplicate.