The Utilisation of Tannin Extract as a Dietary Additive in Ruminant Nutrition: A Meta-Analysis

Abstract

The objective of this meta-analysis was to elucidate whether there are general underlying effects of dietary tannin extract supplementation on rumen fermentation, digestibility, methane production, performance, as well as N utilisation in ruminants. A total of 70 papers comprised of 348 dietary treatments (from both in vivo and in situ studies) were included in the study. The database was then statistically analysed by the mixed model methodology, in which different experiments were considered as random effects and tannin-related factors were treated as fixed effects. The results revealed that an increased level of tannin extract inclusion in the diet lowered ruminant intake, digestibility, and production performance. Furthermore, the evidence also showed that an increased level of tannin extract decreased animal N utilisation where most of rumen by-pass protein was not absorbed well in the small intestine and directly excreted in the faeces. Due to the type of tannin extract, HT is more favourable to maintain nutrient intake, digestibility, and production performance and to mitigate methane production instead of CT, particularly when supplemented at low (<1%) to moderate (~3%) levels.

Effects of Neem (Azadirachta indica) Leaf Powder Supplementation on Rumen Fermentation, Feed Intake, Apparent Digestibility and Performance in Omani Sheep

“…The opposite result (reduced ruminal pH and increased total VFA concentration) was observed with the use of MON, revealing that MON may affect the fermentation pattern through the alteration of microbial populations and/or their metabolic pathways [ 54 ]. This result agrees with previous findings observed with the use of MON [ 35 , 49 ].…”

“…The binding properties of phytochemical constituents (either phenolics or flavonoids) present in neem leaves [ 18 ] might form complexes with dietary proteins [ 49 ], allowing greater fecal nitrogen excretion by lambs fed NLP than those fed MON. Based on this, the shifting nitrogen excretion dynamics from urine toward feces reveals a desirable benefit from an environmental perspective [ 9 ].…”

Divergence effects between dietary Acacia and Quebracho tannin extracts on nutrient utilization, performance, and methane emission of ruminants: A meta‐analysis

“…The present meta‐analysis showed urine N excretion was not affected by dietary tannins. Similar to our result, a meta‐analysis conducted by Yanza, Fitri, et al (2021) reported that dietary tannins extracts did not influenced urine N excretion. This response of the urine N excretion might occur due to the type of tannin (CT) and the form of tannin (extracted or non‐extracted) used in this meta‐analysis.…”

“…To our knowledge, no study has yet summarized the results comprehensively by using meta‐analysis approach. Notably, a previous meta‐analysis study has been conducted to evaluate the use of tannin extracts from various tannin sources and types of tannin (HT and CT) in ruminant (Yanza, Fitri, et al, 2021). The results have been vast and focused on the HT and CT differences.…”

Effect of Yerba Mate Extract as Feed Additive on Ruminal Fermentation and Methane Emissions in Beef Cattle

“…Probably, nutrient intake is not affected by the low inclusion of extract in the diet. As the inclusion of plant extracts containing tannins and other phenolic compounds increases, the animals linearly decrease their dietary intake [ 27 ].…”