## 3 Results and Discussion
### Meat Quality  
In general, there were significant differences (_p_ < 0.005) in physical parameters of the breast and thigh meat of broilers fed with the sold-out substrate of _P. ostreatus_ (from corn stubble) with different percentages of protein compared to those fed with the treatment control diet. In this study, the pH values of breast muscle (BM) and thigh muscle weight (TMW) are within the ranges of normal pH limits [66]. The color of any meat product is one of the most used indicators to determine freshness and healthiness of the meat, obtaining a good initial image of the product [67]. In the present investigation, sold-out substrate with different percentages of protein presented a significant difference (_p_ < 0.05) in color properties of breast muscle (BM) and thigh muscle weight (TMW) meat at 24 h post-mortem between diets of the broilers (Figure 2). Treatment T2 obtained the greatest lightness (L*), redness (a*), and yellowness (b*) unlike the other treatments, which did not present a significant difference with treatment  
Figure 2: Analysis of color characteristics of the breast muscle (BM) and thigh muscle weight (TMW) at 24 h post-mortem of broilers fed diets containing sold-out substrate with different percentages of protein. Means with different letters indicate statistically significant differences by ANOVA and Tukey’s test (_p_ < 0.05). control. In a study conducted by [PERSON] et al. [68], the authors found that broiler meat color characteristics ranged from 53.9 to 55.3 for lightness, 5.7 to 6.3 for redness, and 13.4 to 14.7 for yellowness, which were results higher than those reported in present investigation. Based on the luminosity values proposed by [PERSON] et al. [69], meat is classified as lightest (pale, L\({}^{*}\) > 53), normal (48 < L\({}^{*}\) < 51), and dark (L\({}^{*}\) < 46), based on these values, and according to the results of the present investigation, the values of L\({}^{*}\), a\({}^{*}\), and b\({}^{*}\) for all the treatments were in a normal range (48 < L\({}^{*}\) < 51), which indicates that the breast muscle meat (BM) and the weight thigh muscle weight (TMW) are considered light, soft, and non-exudative [70]. Inclusion of sold-out substrate with different percentages of protein in the broiler diet influenced the moisture%, CP%, EE%, and ash content of breast muscle (BM) and thigh muscle weight (TMW) meat compared to treatment control. In a study conducted by [PERSON] et al. [71], the authors reported 73.88-74.29% muscle moisture; likewise, [PERSON] et al. [72] obtained 75.24-76.14% moisture in broilers, results similar to those reported in the present investigation. Crude protein (PC%) of breast muscle (BM) and thigh muscle weight (TMW) meat in the three treatments with respect to the treatment control showed significant differences (\(p<0.05\)). Control treatment has the highest crude protein content (PC%), which is directly proportional to the amount of crude protein in the commercial feed(r). Protein-rich meats are considered to exhibit good nutritional quality with a proportion of essential amino [73]. According to data collected by [PERSON] [74], breast muscle (BM) can contain 22.5% of crude protein, while the thigh muscle weight (TMW) can have a value of 16.2%. [PERSON] et al. [75] mentioned that the protein of breast muscle (BM) and thigh muscle weight (TMW) can reach values of 23.4, 20.4, and 19.9%, respectively, which are values lower than those found in this research work (Figure 3). The mean contents of ethereal extract (EE = 5.35%) in the present experiment were in good agreement with [PERSON] et al. [72]. The highest ethereal extract content obtained in this work was presented by treatment control and T3 treatment, which do not show significant differences between them; this was confirmed by finding accumulations of fat in the breast muscle (BM) and thigh muscle weight (TMW).