## 4 Discussion  
Weaning weight was similar for the three production systems (6.7 months). Weaning weight is similar because the farms adopt the same animal rearing system. This is the Brazilian weaning standard for beef cattle [1; 2; 30; 31]. Slaughter age, as well as average daily gain and, consequently, slaughter weight are determined by genetics and energy and protein density of the diets. Thus, bulls fed for a longer period in feedlot had a shorter slaughter time and higher slaughter weight. However, slaughter weight determined hot and cold carcass weight, but did not change carcass dressing. The carcass dressings observed in this study are slightly higher than the dressings observed in the production system in Brazil [2; 5; 9; 25; 32]. This high carcass dressing may be correlated with the fattening state and slaughter weight of bulls with subcutaneous fat thickness above 6.0 mm. The pH\({}_{\text{24h}}\) value in the meat of bulls from the FELOT system was above 5.80, considered the limiting pH value and can be explained by the stress caused by the grouping of animals at the time of transport and in the waiting pen for slaughter. In addition, the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameters** & **PASTU 1** & **FELOT 2** & **PRIME 3** & **SEM 4** & \(p\)**Value** \\ \hline \(n\) & 10 & 10 & 10 & & \\ \hline pH & 5.67 b  & 5.64 b  & 5.84 a  & 0.023 & 0.002 \\ Finishing degree, points & 1.30 & 1.40 & 1.40 & 0.150 & 0.775 \\ Subcutaneous fat thickness, mm & 6.76 b  & 7.51 a  & 7.89 a  & 0.737 & 0.021 \\ LDA (_Longissimus dorsi_ area), cm2  & 113.53 a  & 114.19 b  & 115.93 a  & 3.117 & 0.011 \\ Ratio & 0.47 & 0.44 & 0.44 & 0.01 & 0.782 \\ \hline \hline Marbling, frequency, \% & & & & & \\ \hline Little & 16.00 a  & 10.00 b  & 4.00 c  & 2.82 & 0.001  \\ Reasonable & 14.00 b  & 28.00 a  & 16.00 b  & 3.55 & 0.001 \\ Good & 38.00 b  & 28.00 c  & 48.00 a  & 4.69 & 0.001 \\ Very good & 32.00 & 34.00 & 32.00 & 0.53 & 0.305 \\ Excessive & 0.00 & 0.00 & 0.00 & 0.00 & 1.000 \\ \hline Tissue composition, \% & & & & & \\ \hline Muscle & 62.63 & 62.18 & 62.24 & 1.120 & 0.320 \\ Adipose & 18.50 b  & 21.39 a  & 20.18 a  & 0.832 & 0.041 \\ Bone & 18.34 a  & 15.85 b  & 16.92 b  & 0.713 & 0.042 \\ Others & & 0.53 & 0.58 & 0.66 & 0.063 & 0.670 \\ \hline \hline \end{tabular}  
* PASTU—Bulls raised on extensive _Brachiaria_ pasture and finished in feedlot, 2 FELOT—Bulls raised on corrected and fertilized pasture and finished in feedlot, 3 PRIME—Bulls raised and finished in feedlot, 4 SEM—Standard Error of the Mean. Means followed by different letters in the same lines are different (\(p<0.05\)).  
\end{table} 
Table 4: Effect of production system on animal performance, carcass characteristics, pH, marbling and tissue composition of crossbred bulls. pH measured 24 h after slaughter is an important measurement because it can influence several attributes of meat quality [33; 34]. Furthermore, meat pH seems to be much more related to pre- and post-slaughter management than to genetic and nutritional characteristics [35]. Anaerobic glycolysis converts the glycogen present in the muscles into lactic acid, releasing hydrogen (H\({}^{+}\) ions). Enzymatic actions, mainly of calpain, are favored at lower pH, breaking down the proteins of the myofibrils and making the meat more tender and juicier. The production of lactic acid and nitrogen compounds during maturation contributes to the characteristic flavor and aroma of matured meat. The low pH promotes the conversion of myoglobin into oxyhemoglobin, intensifying the red color of the meat [36]. The pH of the meat from animals in the PASTU and FELOT systems were within the range standards found in the literature [34; 37]. [PERSON] et al. [38] and [PERSON] et al. [7] did not observe differences in the pH of the meat between animals finished on pasture or on feedlot 24 h after slaughter. Stressed animals with zebu genetics have higher pH due to the release of stress hormones such as corticosteroids.