Fermentation Parameters and In Vitro Degradability of Diets Containing <scp> <i>Cratylia argentea</i> </scp> Hay as a Substitute for Tifton‐85 Hay

ABSTRACT Cratylia argentea has potential for use in ruminant feed; however, the presence of condensed tannins (CT) can interfere with rumen fermentation dynamics. This study aimed to evaluate the fermentation parameters and in vitro degradability of diets containing C. argentea hay as a substitute for Tifton‐85 hay. The experiment was conducted in a randomised block design with a 3 × 4 factorial arrangement, using incubation times of 24, 48, and 96 h, and varying the inclusion of C. argentea hay at 0%, 20%, 40%, or 100% concentration, with three replicates per treatment. The production of CH 4 [mL/true organic matter (TOM)], gas [mL/dry matter (DM)], CH 4 mL/g DM, the in vitro DM digestibility (IVDMD), organic matter (IVOMD), TOM (TOMD), the partition factor (PF), which quantifies the fraction of total organic matter available for microbial fermentation, pH, the ammonia nitrogen concentrations (NH 3 ‐N), short‐chain fatty acids (SCFA), isoacids and the acetate to propionate ratio were evaluated. Substitution levels did not significantly influence ( p &gt; 0.05) CH 4 production, gas, PF, pH, NH 3 ‐N, SCFA, or isoacids. CH 4 mL/g DM showed quadratic behaviour ( p &lt; 0.05), whereas digestibility coefficients showed a linear reduction at 96 h of incubation, probably due to fibre and CT concentrations in legume hay. However, these coefficients at the 40% inclusion level were similar to the treatment without legume hay at 96 h of incubation. Therefore, the fermentation and in vitro degradability parameters suggest that C. argentea hay can replace Tifton‐85 hay by up to 40% in ruminant feed with the potential to reduce enteric CH 4 production.