A composition for use in the prevention or treatment of Salmonellosis in animals, said use comprising administering the composition to the animal, wherein the composition contains (i) at least 0.01% by weight of dry matter of rhamnogalacturonan I (RG-I) polysaccharides and (ii) at least 10% by weight of the pectic polysaccharides being RG-I polysaccharides, said RG-I polysaccharides having a molecular weight of at least 20 kDa and having a backbone consisting of galacturonic acid residues and rhamnose residues, said rhamnose residues being contained in alpha(1→4)-galacturonic-alpha(1→2)-rhamnose residues, wherein: • rhamnose residues represent 4-35% of the monosaccharide residues contained in the RG-I polysaccharides; • galacturonic acid residues represent 20-70% of the monosaccharide residues contained in the RG-I polysaccharides; • the molar ratio of galacturonic acid residues to rhamnose residues in the RG-I polysaccharides is within the range of 9:1 to 1:1; • the molar ratio of arabinose residues to rhamnose residues in the RG-I polysaccharides is less than 8:1; • the molar ratio of galactose residues to rhamnose residues in the RG-I polysaccharides is less than 5:1; • the combination of arabinose residues and galactose residues and rhamnose are present in the RG-I polysaccharides in a molar ratio of less than 10:1; • 0-50% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of a methyl ester; and • 8-30% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of an acetyl ester; wherein pectic polysaccharide are optionally branched polysaccharides having a molecular weight of more than of 2 kDa and comprising a backbone that consists of galacturonic acid residues and rhamnose residues, said rhamnose residues being contained in alpha(1→4)-galacturonic-alpha(1→2)-rhamnose residues. (i) at least 0.01% by weight of dry matter of rhamnogalacturonan I (RG-I) polysaccharides and (ii) at least 10% by weight of the pectic polysaccharides being RG-I polysaccharides, said RG-I polysaccharides having a molecular weight of at least 20 kDa and having a backbone consisting of galacturonic acid residues and rhamnose residues, said rhamnose residues being contained in alpha(1→4)-galacturonic-alpha(1→2)-rhamnose residues, wherein: • rhamnose residues represent 4-35% of the monosaccharide residues contained in the RG-I polysaccharides; • galacturonic acid residues represent 20-70% of the monosaccharide residues contained in the RG-I polysaccharides; • the molar ratio of galacturonic acid residues to rhamnose residues in the RG-I polysaccharides is within the range of 9:1 to 1:1; • the molar ratio of arabinose residues to rhamnose residues in the RG-I polysaccharides is less than 8:1; • the molar ratio of galactose residues to rhamnose residues in the RG-I polysaccharides is less than 5:1; • the combination of arabinose residues and galactose residues and rhamnose are present in the RG-I polysaccharides in a molar ratio of less than 10:1; • 0-50% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of a methyl ester; and • 8-30% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of an acetyl ester; • rhamnose residues represent 4-35% of the monosaccharide residues contained in the RG-I polysaccharides; • galacturonic acid residues represent 20-70% of the monosaccharide residues contained in the RG-I polysaccharides; • the molar ratio of galacturonic acid residues to rhamnose residues in the RG-I polysaccharides is within the range of 9:1 to 1:1; • the molar ratio of arabinose residues to rhamnose residues in the RG-I polysaccharides is less than 8:1; • the molar ratio of galactose residues to rhamnose residues in the RG-I polysaccharides is less than 5:1; • the combination of arabinose residues and galactose residues and rhamnose are present in the RG-I polysaccharides in a molar ratio of less than 10:1; • 0-50% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of a methyl ester; and • 8-30% of the galacturonic acid residues in the RG-I polysaccharides is esterified in the form of an acetyl ester;