In vitro ruminal-microbial fermentation pattern: nutritional insights about some agricultural crop mesocarps (peel)...

Different agricultural crop wastes (ACW) such as mesocarps (peel) are annually produced after consuming their edible parts in the world without any scientific information about their nutritional potential. Therefore, a study was conducted to determine the ruminal-microbial fermentation pattern and nutritional potential of some crop mesocarps (peel) including different species of melons (Watermelon, Galia melon, Rockmelon, Til sabz, and Til atashi) as well as cucumber and eggplant using common and standard laboratory methods. The amount of crude protein (CP) varied from 7.19 to 19.1% of dry matter (DM) for Til sabz and cucumber mesocarps, respectively. The highest (34.1% of DM) and lowest (15.4%) content of neutral detergent fiber (NDF) were related to eggplant and Til sabz peels, respectively (p < 0.05). The content of non-fiber carbohydrates (NFC) varied from 38.7% for eggplant peel to 66.6% for Til sabz. All mesocarps had a low DM percentage (4.88% of DM for cucumber to 8.45 for eggplant). Rockmelon peel had the highest amount of calcium (5.25 g/kg DM) and magnesium (5.75 g/kg DM) compared with the other mesocarps (p < 0.05). The highest amounts of potassium (33.4 g/kg of DM), sodium (7.15 g/kg of DM), and zinc (21 mg/kg of DM) were observed in the peels of watermelon, Til atashi, and cucumber, respectively (p < 0.05). The potential of ruminal-microbial gas production also differed from 55.6 ml/200 mg of DM for eggplant to 63.1 ml for Til sabz peel. Except for cucumber (8.75 MJ/kg of DM) and eggplant (8.71 MJ), other mesocarps (different melon species) had almost similar metabolizable energy (ME, 9.06-9.50 MJ/kg of DM). Among the studied mesocarps, the lowest ruminal-microbial DM and organic matter (OM) digestibility was also observed in eggplant and cucumber (p < 0.05). Gallia melon had the highest acid-base buffering capacity (267 mEq×10^- 3, p < 0.05). According to our findings, the mesocarps of melons showed a higher nutritional value than the cucumber and eggplant. In general, Til sabz exhibited a notable favorite and superior nutritional characteristic compared with the other mesocarps.