Intraruminal administration of two doses of quebracho tannins to sheep: effect on rumen degradation and total tract digestibility, faecal recovery and toxicity

Safety and efficacy of a feed additive consisting of an extract of condensed tannins from Schinopsis balansae Engl. and Schinopsis lorentzii (Griseb.) Engl. (red quebracho extract) for use in all animal species (FEFANA asbl)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of an extract of condensed tannins from Schinopsis balansae Engl. and Schinopsis lorentzii (Griseb.) Engl. (red quebracho extract) when used as a sensory additive in feed and water for drinking for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive under assessment is safe up to the maximum proposed use levels of 400 mg/kg for chickens for fattening and other growing poultry, 600 mg/kg for laying hens and other laying/breeding birds kept for egg production/reproduction, 540 mg/kg for turkeys for fattening, 720 mg/kg for piglets, 860 mg/kg for pigs for fattening and other growing Suidae, 1,050 mg/kg for sows, 1,680 mg/kg for veal calves (milk replacer), 1,580 mg/kg for cattle for fattening and other growing ruminants, 1,030 mg/kg for dairy cows and other dairy ruminants, 1,580 mg/kg for sheep, goats, horses, 630 mg/kg for rabbits, 1,810 mg/kg for salmonids and other fin fish, 1,900 mg/kg for dogs and 3,000 mg/kg for ornamental fish. For cats, the calculated safe concentration in feed is 317 mg/kg complete feed. For all the other minor species, the additive is considered safe at 317 mg/kg complete feed. The FEEDAP Panel considered the use in water for drinking as safe provided that the total daily intake of the additive does not exceed the daily amount that is considered safe when consumed via feed. No concerns for consumers were identified following the use of the additive at the maximum proposed use level in feed. The extract under assessment is not an eye irritant but in the absence of data, no conclusion can be drawn on its potential to be a skin irritant and a dermal and respiratory sensitiser. The use of the extract under the proposed conditions of use in feed was not expected to pose a risk for the environment. Since quebracho and its preparations were recognised to flavour food and its function in feed would be essentially the same as that in food, no further demonstration of efficacy was considered necessary.

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

Extracts of Acacia and Quebracho have been used as a feed additive in ruminant diets; the effects, however, have been varied. This study used a meta-analysis approach to evaluate the use of those extracts on nutrient utilization, performance, and methane production of ruminants. A database was developed from 37 published papers comprising 152 dietary treatments. The result showed that a higher concentration of tannins was associated with a decrease (p < 0.05) in nutrient intake and digestibility. An increasing tannin concentration was negatively correlated with ammonia, acetic acid, and the ratio of acetic to propionic acid. Methane production decreased (p < 0.01) with the increasing tannin concentration. Nitrogen (N) balance parameters were not affected by the tannin concentrations, but fecal N excretion increased (p < 0.01) as the tannin concentration increased. The relationships between the Acacia and Quebracho and the changes in organic matter intake, milk fat concentration, butyric acid, valeric acid, and methane production were significantly different. In conclusion, it is possible to use both condensed tannins (CT) extracts as a methane emission mitigation without impairing the ruminant performance. Furthermore, the Quebracho showed more pronounced to decrease ruminal protein degradation and lower methane emission than the Acacia.

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

Simple Summary

Tannin has been extensively assessed for its potential and utilisation as a ruminant feed additive in recent years and is becoming important due to its beneficial effects on modulating ruminant performance and health and mitigating methane emissions. However, evidence concerning the effect of tannin in extracted forms on ruminants appears to be inconclusive on whether it can genuinely provide either beneficial or detrimental effects for ruminants. Moreover, the effects of various sources, types of tannin extract, or appropriate levels of supplementation on ruminants remain unclear. Therefore, there is a need for a systematic evaluation concerning the effects of tannin extract on rumen fermentation, digestibility, performance, methane emissions, and metabolism of ruminants.

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.

Flavan-3-ols: nature, occurrence and biological activity

Representing the most common flavonoid consumed in the American diet, the flavan-3-ols and their polymeric condensation products, the proanthocyanidins, are regarded as functional ingredients in various beverages, whole and processed foods, herbal remedies and supplements. Their presence in food affects food quality parameters such as astringency, bitterness, sourness, sweetness, salivary viscosity, aroma, and color formation. The ability of flavan-3-ols to aid food functionality has also been established in terms of microbial stability, foamability, oxidative stability, and heat stability. While some foods only contain monomeric flavan-3-ols [(-)-epicatechin predominates] and dimeric proanthocyanidins, most foods contain oligomers of degree of polymerization values ranging from 1-10 or greater than 10. Flavan-3-ols have been reported to exhibit several health beneficial effects by acting as antioxidant, anticarcinogen, cardiopreventive, antimicrobial, anti-viral, and neuro-protective agents. This review summarizes the distribution and health effects of these compounds.

Results of a screening programme to identify plants or plant extracts that inhibit ruminal protein degradation

One aim of the EC Framework V project, ’Rumen-up’ (QLK5-CT-2001-00 992), was to find plants or plant extracts that would inhibit the nutritionally wasteful degradation of protein in the rumen. A total of 500 samples were screenedin vitrousing14C-labelled casein in a 30-min incubation with ruminal digesta. Eight were selected for further investigation using a batch fermentation system and soya protein and bovine serum albumin as proteolysis substrates; proteolysis was monitored over 12 h by the disappearance of soluble protein and the production of branched SCFA and NH3. Freeze-dried, ground foliage ofPeltiphyllum peltatum,Helianthemum canum,Arbutus unedo,Arctostaphylos uva-ursiandKnautia arvensisinhibited proteolysis (P < 0·05), whileDaucus carota,Clematis vitalbaandErica arboreahad little effect. Inhibition by the first four samples appeared to be caused by the formation of insoluble tannin–protein complexes. The samples were rich in phenolics and inhibition was reversed by polyethyleneglycol. In contrast,K.arvensiscontained low concentrations of phenolics and no tannins, had no effect in the 30-min assay, yet inhibited the degradation rate of soluble protein (by 14 %,P < 0·0001) and the production of branched SCFA (by 17 %,P < 0·05) without precipitating protein in the 12-h batch fermentation. The effects showed some resemblance to those obtained in parallel incubations containing 3 μm-monensin, suggesting thatK.arvensismay be a plant-derived feed additive that can suppress growth and activity of key proteolytic ruminal micro-organisms in a manner similar to that already well known for monensin.