Impact of Tannin Supplementation on Proteolysis during Post-Ruminal Digestion in Wethers Using a Dynamic In Vitro System: A Plant (Medicago sativa) Digestomic Approach.

The aim of this study was to characterize the effects of tannins on plant protein during sheep digestion using a digestomic approach combining in vivo (rumen) conditions and an in vitro digestive system (abomasum and small intestine). Ruminal fluid from wethers infused with a tannin solution or water (control) was introduced into the digester, and protein degradation was followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Tannin infusion in the rumen led to a clear decrease in protein degradation-related fermentation end-products, whereas ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) protein was more abundant than in control wethers. In the simulated abomasum, peptidomic analysis showed more degradation products of RuBisCo in the presence of tannins. The effect of RuBisCo protection by tannins continued to impact Rubisco digestion into early-stage intestinal digestion but was no longer detectable in late-stage intestinal digestion. The peptidomics approach proved a potent tool for identifying and quantifying the type of protein hydrolyzed throughout the gastrointestinal tract.

Tannin supplementation modulates the composition and function of ruminal microbiome in lambs infected with gastrointestinal nematodes.

This study was carried out to evaluate the effects of tannin supplementation on ruminal microbiota of sixteen lambs infected and non-infected with Haemonchus contortus and Trichostrongylus colubriformis. Animals were fed with hay, concentrate and supplemented with Acacia mearnsii (A. mearnsii). The animals were divided into four treatments: two control groups without infection, either receiving A. mearnsii (C+) or not (C-), and two infected groups, one with A. mearnsii (I+) and another without A. mearnsii (I-). Ruminal short-chain fatty acids (SCFA) and metagenome sequencing of ruminal microbiota were used to evaluate the effect of tannin and infection on ruminal microbiome. For SCFA, differences were observed only with A. mearnsii. Total SCFA and acetate molar percentage were decreased in C+ and I+ (P<0.05). Butyrate, valerate and isovalerate were higher in lambs that received A. mearnsii in the diet (P<0.05). The infection changed the microbiome structure and decreased the abundance of butyrate-producing microorganisms. In addition, A. mearnsii supplementation also affected the structure the microbial community, increasing the diversity and abundance of the butyrate-producing and probiotics bacteria, amino acid metabolic pathways, purine, pyrimidine and sphingolipid metabolism. Together, our findings indicate that A. mearnsii supplementation modulates important groups related to nitrogen, amino acid, purine and pyrimidine metabolism, in rumen microbiome, affected by gastrointestinal nematodes infection in lambs.

Effects of Acacia mearnsii supplementation on nutrition, parasitological, blood parameters and methane emissions in Santa Inês sheep infected with Trichostrongylus colubriformis and Haemonchus contortus.

Gastrointestinal nematodes are a main problem for ruminant production, reducing animal performance and increasing environmental impact per unit of animal product generated. Tannin supplementation may lead to positive results regarding aspects such as parasitic infections and methane (CH4) emissions. Therefore, the objective of this experiment was to evaluate the effects of the condensed tannins (CT) extract made of powdered Acacia mearnsii bark (PAB) on nutrition, parasitic status and CH4 emissions in sheep artificially infected with Trichostrongylus colubriformis and Haemonchus contortus. Twenty 10-month old Santa Inês lambs (24.7 ± 3.14 kg of initial body weight) were used in a 50-day trial. Animals were divided in four treatment groups according to parasitic infection and PAB supplementation: two control groups without infections, one without PAB (C-) (n = 4) and one with PAB (C+) (n = 4); two infected groups, one without PAB (I-) (n = 6) and another receiving PAB (I+) (n = 6). Initially, animals were kept in individual pens where they were fed ad libitum chopped tifton 85 hay (Cynodon spp.) and 210 g/animal/day of concentrate. On the first day of experiment, animals of I- and I+ groups were artificially infected with infective larvae (L3) of T. colubriformis and H. contortus. Lambs were weighed fortnightly to calculate average daily body weight gain (ADG). Blood and faeces samples were also collected in the same moment of weighing for the evaluation of blood parameters and faecal egg count (FEC) respectively. After 40 days of experiment, measurements of CH4 emissions in small chamber system started and following that, apparent total tract digestibility (ATTD) assay was carried out in metabolic cages. In the end of experimental period (50 days), lambs were slaughtered and samples of abomasum and small intestine content were collected for worm count, identification, and eggs/female count. No significant (p > 0.05) treatment effects were verified for ADG, ATTD and worm count. Blood parameters were affected in both infected groups (p < 0.05) from the 28th experimental day onwards, when these animals started to show reduced red blood cells, haemoglobin and packed cell volume when compared to C- and C+. Decreased FEC was verified in I+ when compared to I- and also, H. contortus eggs/female worm for I+ was lower than for I- (p < 0.05). Both infected groups showed higher CH4 emissions than the control groups (p < 0.05). Results highlighted the anthelmintic potential of PAB and indicated methanogenic effect of parasitic nematode infections.

Comparison of the in vitro anthelmintic effects of Acacia nilotica and Acacia raddiana.

Gastrointestinal nematodes are a major threat to small ruminant rearing in the Sahel area, where farmers traditionally use bioactive plants to control these worms, including Acacia nilotica and Acacia raddiana. The main aim of this study was to screen the potential anthelmintic properties of aqueous and acetone extracts of leaves of these two plants based on three in vitro assays: (1) the egg hatch inhibition assay (EHA); (2) the larvae exsheathment inhibition assay (LEIA) using Haemonchus contortus as a model; and (3) an adult mortality test (AMT) applied on Caenorhabditis elegans. For the EHA, only A. raddiana was effective with IC50 = 1.58 mg/mL for aqueous extract, and IC50 = 0.58 mg/mL for acetonic extract. For the LEIA, all extracts inhibited the exsheathment of larvae compared to the controls, and the aqueous extract of A. nilotica was more larvicidal with IC50 = 0.195 mg/mL. In general, all responses to the substances were dose-dependent and were significantly different from the control group (p < 0.05). For the AMT, the extracts of the two Acacia species were effective but A. raddiana showed greater efficacy with 100% mortality at 2.5 mg/mL and LC50 = 0.84 mg/mL (acetonic extract). The addition of polyvinyl polypyrrolidone (PVPP) to the extracts suggested that tannins were responsible for blocking egg eclosion and inducing adult mortality but were not responsible for exsheathment inhibition. These results suggest that the leaves of these Acacia species possess ovicidal and larvicidal activities in vitro against H. contortus, and adulticidal effects against C. elegans.

Sodium Hydroxide Enhances Extractability and Analysis of Proanthocyanidins in Ensiled Sainfoin (Onobrychis viciifolia).

Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone-butanol-HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.