This study aimed to assess the quality of Mojosari duck carcasses using calcium complexes and phytobiotic jamu waste in their feed. The study involved 120 ducks aged 24 weeks and used a randomized design with six treatments and four replications. The results showed that phytobiotic calcium supplementation did not significantly improve carcass quality parameters such as carcass weight, abdominal fat, or abdominal fat percentage. However, it significantly influenced the gizzard and levels of ammonia excreta and volatile fatty acids in the cecum. The study concluded that the inclusion of calcium phytobiotics in duck diets did not lead to significant improvements in the carcass quality parameters. The most effective treatment was basal feed supplemented with 0.75% calcium phytobiosis, which decreased excreta ammonia concentrations and enhanced volatile fatty acids in the cecum.