Fruit byproducts represent a sustainable alternative to conventional feed for ruminants, addressing food-feed competition and environmental concerns. Two experiments were performed to investigate the use of mango and avocado byproducts as feed ingredients and supplements, focusing on chemical composition, in vitro digestibility, and rumen fermentation characteristics. Experiment 1 assessed these parameters for mango peel (MP), mango seed kernel (MSK), mango seed coat (MSC), avocado peel (AP), and avocado seed (AS). Experiment 2 evaluated rumen fermentation parameters using a control (200 mg alfalfa hay) and four treatments, each with 200 mg alfalfa hay supplemented with 15 mg beta-cyclodextrin microencapsulated extracts: MPE (mango peel microencapsulated extract), APE (avocado peel microencapsulated extract), MSKE (mango seed kernel microencapsulated extract), or ASE (avocado seed microencapsulated extract). MSK had the highest crude protein content, whereas AP had the highest ether content. MSC and AP presented the highest fiber fractions. AP and MP showed higher total phenolic content and antioxidant capacity. In experiment 1, MSK, AS and MP resulted in greater invitro dry matter digestibility, metabolizable energy, and cumulative gas production compared to MSC and AP. AS, MSC, and MSK presented higher acetate to propionate ratios than MP and AP did. MSK resulted in the highest methane concentration, while AP and MSC produced the lowest. Ammonia nitrogen was highest in AP and lowest in MSC. In experiment 2, MSKE, ASE and the control had the highest cumulative gas production, followed by APE and MPE. Compared with the other treatments, APE reduced both the acetate-to-propionate ratio and methane production. Compared with the control, all the encapsulated extracts lowered the ammonia nitrogen concentration. Overall, MP, MSK, and AS have emerged as the most promising ingredients because of their relatively high digestibility, metabolizable energy, and fermentation efficiency, whereas APE and MPE have potential as feed supplements for reducing methane production.
