Potential Effect of Dietary Supplementation of Tannin-Rich Forage on Mitigation of Greenhouse Gas Production, Defaunation and Rumen Function.

This experiment evaluated the effect of including Acacia mearnsii leaves in a high-fiber diet (corn stover), on ruminal degradation kinetics, digestibility, microbial biomass production, and gas, CH 4 , and CO 2 production. Four experimental diets were tested, including a control with 100% corn stover (T1), and three additional diets with corn stover supplemented at 15% A. mearnsii leaves (T2), 30% A. mearnsii leaves (T3) and 45% of A. mearnsii leaves (T4). The highest dry matter in situ degradation ( p ≤ 0.001) and in vitro digestibility ( p ≤ 0.001) was found in T1 (80.6 and 53.4%, respectively) and T2 (76.4 and 49.6%, respectively) diets. A higher population of holotrich and entodiniomorph ruminal protozoa was found ( p = 0.0001) in T1 at 12 and 24 h. Diets of T1 and T2 promoted a higher ( p = 0.0001) microbial protein production (314.5 and 321.1 mg/0.5 g DM, respectively). Furthermore, a lower amount of CH 4 was found ( p < 0.05) with T2, T3 and T4. It is concluded that it is possible to supplement up to 15% of A. mearnsii leaves (30.5 g TC/kg DM) in ruminant's diets. This decreased the population of protozoa (holotrich and entodiniomorph) as well as the CH 4 production by 35.8 and 18.5%, respectively, without generating adverse effects on the ruminal degradation kinetics, nutrient digestibility and microbial protein production.