Changes in in vitro ruminal and post‐ruminal degradation of tropical tannin‐rich legumes due to varying levels of polyethylene glycol

Abstract

We evaluated the effects of tannins from Flemingia macrophylla (CIAT 17403) and Calliandra calothyrsus (San Ramón CIAT 22310 and Patulul CIAT 22316) on in vitro ruminal and post-ruminal dry matter and apparent protein degradation. For each tannin source (legumes), different dosages of polyethylene glycol (PEG) (8000 Da) in McDougall buffer were added to achieve ratios of 0:3, 1:3, 2:3 and 3:3 PEG:condensed tannin (CT). Ruminal fluid mixed with McDougall buffer (1:4) was added to tubes containing only legume foliage (control) or PEG-treated legume foliage. For both Calliandra varieties, a higher ruminal dry matter degradation was observed at a PEG:CT ratio of 3:3. For F. macrophylla, no differences were found between 2:3 and 3:3 ratios (p > 0.05), indicating that a PEG:CT ratio of 2:3 might be enough to bind tannins. Increasing PEG:CT ratios increased apparent ruminal degraded protein and ammonia concentration (p < 0.0001) differing among species (species × ratio: p < 0.0001). The degradation of bypass crude protein (dBCP) was influenced by both legume type and PEG:CT ratio (p < 0.0001). For Patulul, as PEG:CT ratio increased, dBCP increased, but after tannin ratio of 2:3, there was not a significant increase, and for San Ramón, dBCP degradation was higher as PEG:CT ratio increased up to 2:3. For Flemingia, dBCP was higher than PEG:CT ratio of 0:3 but not different among 1:3, 2:3 or 3:3. Low concentration of CT (116 mg/g DM) increased the proportion of protein digested in the abomasum, but higher levels of CT (252 mg/g) clearly reduced the proportion of digested CP. For Flemingia, PEG:CT ratio of 2:3 is enough to inactivate tannins, while PEG:CT ratio of 3:3 was needed for Calliandra and consequently increased ruminal degradation of dry mater (rdDM), and crude protein (rdCP), total degradation of dry matter (tdDM), crude protein (tdCP) and ammonia levels.

Ruminal ammonia concentration and fermentation kinetics of commercial herbal feed additives with amino acids

“…Finally, A. sativum is a rich source of essential oils and organosulphurous compounds such as allicin, with specific antimicrobial activities. Total phenols, condensed tannins and essential oils present in this plant appear to be biologically active secondary metabolites, which modify rumen fermentation (22,23,34) and explain the resistance to protein degradation in the in vitro incubation. Ruminal fermentation parameters are shown in table 2 (page 291).…”

“…The most studied antinutritional factors are tannins, followed by secondary plant metabolites such as saponins, cyanogenic compounds, lecithins, alkaloids, oxalic acid and flavonoids (18,19,29). These factors can influence rumen protein degradation and synthesis, either by directly affecting the ruminal microorganisms, or by their interaction with nutrients (8,22,27).…”

“…However, several herbaceous legumes such as Phaseolus spp and Trigonella spp have high concentrations of polyphenolic compounds (mainly tannins) and other secondary metabolites, that allow some protection from ruminal microorganisms. These tannins affect bacterial populations, improving ruminal fermentation efficiency, performing as natural feed additives (22,25). These plants could increase amino acid absorption in the intestine.…”

Supplementation of Pelleted Hazel (Corylus avellana) Leaves Decreases Methane and Urinary Nitrogen Emissions by Sheep at Unchanged Forage Intake

“…This indicates that the cleavage of the tannin-protein bonds in the lower gut was not efficient enough to maintain or improve the metabolic supply with protein and amino acids. Whether or not the tannin-protein complexes protected from ruminal degradation are cleaved depends on the type of tannin, its chemical structure and structural flexibility 34 as well as on the pH of the gut environment 11 . The presence of tannins may even enhance endogenous N losses, leaving the extent to which the increased faecal N losses are really caused by a decreased true N digestibility unclear 17 .…”

Effects of Dietary-SCFA on Microbial Protein Synthesis and Urinal Urea-N Excretion Are Related to Microbiota Diversity in Rumen

“…The precipitate was resuspended in McDougall’s buffer and centrifuged at 21000 × g , for 30 min. McDougall’s buffer is an artificial ovine saliva widely used in rumen microbial culture (McDougall, 1948; Knowles et al, 2017). This process was repeated three times.…”