Urea Supplementation Increases Crude Protein and Alters pH but Does Not Affect Ruminal Degradability of Opuntia Silages

The nutritional potential of Opuntia forage is limited by its low crude protein (CP) content. Urea supplementation enhances low-quality forages, but its application in Opuntia silage and its influence on ruminal degradability are limited. This study evaluated the effects of urea addition (0, 20, 40, 60, or 80 g/kg of dry matter (DM)) and ensiling duration (0, 4, 8, 16, 24, or 28 d) on the silage pH and in situ DM degradability of four Opuntia species. Silage pH was influenced by both species and urea level, with greater values observed in silages treated with urea at 80 g/kg DM. The effective degradability of DM (EDDM) was influenced by Opuntia species and was reduced at the highest urea level. In contrast, the ensiling period beyond 12 d did not affect EDDM, and pH stabilized for all treatments after this point. Urea supplementation increases CP content and modifies silage pH but does not improve ruminal degradability. It is recommended that the addition of urea in Opuntia silages should not exceed 60 g/kg DM to avoid reduced fermentative quality. A study limitation is the absence of fermentation end-product data, which would offer a more complete quality assessment.