LGMALGMA U M C Unité de Recherche sur les Herbivores Arhab R 1, 2., Macheboeuf D 3. Bergeaut R 3., Laassalas B 3.& Bousseboua H 2. adress: 1- Département des Sciences de la Nature et de la Vie, C.U. Tébessa, Route de Constantine, (Algérie). 2- Laboratoire de Génie Microbiologique et Applications, Université Mentouri, Constantine (Algérie). 3- Unité de Recherches sur les Herbivores, INRA, Saint-Genès Champanelle (France).

Substrates studied were originated from arid zones. They were submitted to different stresses: temperature, salinity. In response to these harsh climatic conditions, plants synthetize different secondary metabolits. metabolites were group of substances which comprised saponins, flavonoïds, tanins etc). These moieties were considered as antinutritif factors. Secondary metabolites were group of substances which comprised saponins, flavonoïds, tanins etc). These moieties were considered as antinutritif factors. phenolic compounds (tannins) were divided into two groups : phenolic compounds (tannins) were divided into two groups : Tannins Hydrolysable Tannins metabolized by ruminal microbiota Condensed Tannins 1- Review

Intake depression Deleterious effects of tannins Decrease availability of nutrient Inhibition of digestive enzymes Ruminal microbiota toxicity 2. Aims Assessment of tannins effects on ruminal microbiota activity by determination their influence on fermentation parameters: gas production, digestibility and microbial biomass production. Biological effect of tannins was reaveled by polyethylene glycol addition (PEG, PM = 4000 Da), used as specific binding of tannins.

3- Material and methods - Phytochemical analysis of antimicrobial factors (Larrahondo, 1983 ; Rosales et al., 1989) Extraction 15 g of substrate + 30 ml methanol (80%, v/v), 40 mn Filtration Trempage Residue + hot water, 20 mn Decantation Aqueous phase Non polaire phase Non polaire phase 1 ml aqueous extract, shaken for 30s Foam formation Saponins 1 ml methanol extract + 2 ml H 2 O FeCl 3, 2% Tannins 10 ml aqueous extract + 10 ml of ether Chloroforme + acetic acid (0,5 ml) Steroids Steroids Heigh Change in Colour Greenish blue Colour

- Quantitative analysis of phenolic compounds Plant material Extraction : 200 mg dried sample + acetone (10 ml, 70%) Mixture Centrifugation : 3000 g, 10 mn, 4°C Supernatant  Total phenols: Folin-Ciocalteu reaction (Makkar et al., 1993).  Total tannins: PVPP-tannins complexes (Makkar et al., 1993).  Condensed tannins : n butanol-HCl reaction (Porter et al., 1986). Acide tannic equivalent Leucocyanidin equivalent Pellet

- Radial diffusion assay (Hagerman, 1987) d Precipitation area due to tannins-BSA reaction A2 A1 A2 A1 wells bored in the agarose Agarose + BSA

- Polyethylene glycol (PEG) tannins bioassay (Makkar et al., 2003) Gas Substrate Substrate + PEG Microbial biomass (PBM) Tannins effect Tannins + PEG = Tannins-PEG complexes Gas f (∆ Gas, ∆ PBM)

- Calculations and statistical analysis Syringe content 100 ml NDS Filtration through glass crucible N°2 Dessiccation 100°C, 10 hours Incineration 550°C, 6 hours XY   Organic matter digestibility:  Microbial biomass production:  Partitioning factor: X = residual dry matter Y = residual ash Z = initial organic matter V t = Gas production at 24 hours  Data were subjected to analysis of variance (ANOVA). They were analysed based on the statistical model:

Table 1. Phytochemical analysis of antimicrobial factors and quantitative analysis of phenolic compounds (g/kg DM, standard equivalent) of selected feedstuffs. 4- Results

Gas production, ml/200 mg DM A.plumosaD. forskahliiA. gombiformis G. saharaeLeavesracemesVetch-oat hay Substrates - PEG + PEG Figure 1. Corrected gas volume after 24 h of incubation in the absence and presence of polyethylene glycol of the selecetd feedstuffs. -9,4 % 5.96 % 64,1 % 20,05 % 55,2 % 15,4 % 23,6 %

IVTOMD, g/100 g DM A.plumosaD. forskahliiA. gombiformisG. saharaeLeavesRacemesVetch-oat hay Substrates - PEG + PEG 25,7 units 24,9 units 20,07 units 5,98 units 3,57 units 3,25 units 1,2 units Figure 2. Effect of polyethylene glycol on in vitro organic matter digestibility of forages sampled from the North African arid zones.

Partitioning factor, mg/ml A.plumosaD. forskahliiA. gombiformis G. saharaeLeavesRacemesVetch-oat hay Substrats - PEG + PEG Figure 3. Effect of polyethylene glycol addition on partitioning factor of substrates. - 2,01 units - 0,7 units + 0,91 units - 1,05 units + 1,47 units - 0,2 units + 0,02 units

Effect of tannins was more pronounced on degradability of substrates than in vitro gas production. This influence was mainly related to tannins structure than their concentration. Establishment the probable linkage between tannins structure and their capacity to inhibit ruminal hydrolytic enzymes (digestion) and/or fermentative enzymes (gas production). 5- Conclusions

Laboratoire de phytochimie, Université Mentouri. Rouati Tahar Zellagui Ammar Institut Technique des Elevages, Ain Mlila Dehimi Azzouz Dib Youcef URH Michel Doreau Didier Macheboeuf Jean-Baptiste Coulon Jean-Pierre Jouany Diego Morgavi Hamid Boudra Roger Bergeault Bernadette Lassalas David Alvarez Laboratoire de Génie Microbiologique et Applications Bousseboua Hacène. Henniche Satoufa Sakhri Nedjoua Boufenara Souheil Rira Moufida Medjekal Samir Université Larbi Tébessi, Tébessa Gouasmia Abdelkrim Chemmam Fayçal Bouguessa Slim Maàlem Azzeddine Acknowledgements