Abstract

Simple Summary Livestock production systems are responsible for 37 and 64% of total anthropogenic methane (CH4) and ammonia (NH3) overall planet emissions, respectively. Due to the growing demand for meat and milk, mitigating their environmental impact is a major concern. A novel tannin-rich phenolic extract from radiata pine bark (PBE) has the potential to reduce CH4 and NH3 nitrogen (NH3-N) production and modulate rumen fermentation but has not been compared with other commercial phenolic extracts. This study compared PBE with a quebracho extract (QTE). Both extracts decreased butyrate proportion, CH4, total volatile fatty acids, NH3-N production, and increased acetate proportion. Inclusion of QTE increased the propionate proportion but decreased DM disappearance. Results indicate that PBE has the potential to contribute to sustainable livestock production; however, further in vivo studies are needed to verify our results. The aim of this study was to compare the effects of a pine (Pinus radiata D. Don) bark extract (PBE) with a quebracho (Schinopsis balansae Engl.) extract (QTE) on methane (CH4) production and in vitro rumen fermentation parameters. A forage diet supplemented with PBE or QTE (0, 2 and 4% dry matter (DM) basis) was incubated for 24 h to determine in vitro DM disappearance (IVDMD), CH4, volatile fatty acids (VFA), and ammonia nitrogen (NH3-N) production. Differences were analyzed using Tukey's test, orthogonal contrasts, hierarchical clustering heatmap (HCH), and principal component analysis (PCA). Both extracts (4% DM) decreased butyrate (Bu; p = 0.001), CH4 (p = 0.005), total VFA (p 0.001), and NH3-N (p = 0.006) production and increased acetate (Ac; p = 0.003) without affecting the partitioning factor (p = 0.095). Propionate (Pr; p = 0.016) was increased, whereas IVDMD (p = 0.041) was decreased with QTE (4% DM). The inclusion of QTE (2% DM) decreased CH4 production (p = 0.005) and the (Ac + Bu)/Pr ratio (p = 0.003), whereas PBE (2% DM) decreased the NH3-N (p = 0.006) and total VFA production (p 0.001). The HCH and PCA indicate a negative correlation (r = -0.93; p 0.001) between CH4 production and tannins. In conclusion, PBE shares many of the effects generated by QTE on ruminal fermentation, although the magnitude of these effects depends on concentration. The PBE could be used as an additive in ruminant diets to reduce CH4 and NH3-N production without reducing IVDMD or increasing propionate, but further in vivo studies are required to clarify its effects on animal production.