In vitro fermentation characteristics for pigs of hulless barleys differing in β-glucan content

Isolated non-starch polysaccharides (NSP), especially isolated β-glucan, are reported to have
prebiotic effects in pigs. However, little information is available on their possible functional
properties when they are still present in the fibrous matrix of whole cereals. Hulless barleys
(hB) are rich but variable sources of β-glucan. In order to evaluate their potential as functional
feeds, an in vitro experiment was carried out to study the fermentation characteristics of 6 hB
varieties and breeding lines varying in their β-glucan content (36–99 g/kg DM) in comparison
to three hulled barleys (HB), two oat groats, three oats and one wheat, taken as reference. After
pepsin–pancreatin hydrolysis, the ingredients were incubated in a buffered mineral solution
and pig faeces (inoculum). The accumulated gas production, proportional to the amount of
fibre fermented, was measured for 48 h and modelled. Short-chain fatty acid (SCFA) and
ammonia concentrations were measured in the fermented solutions. A cereal type effect
(Pb0.05) was observed on the fermentation kinetics parameters. Rates of degradation and total
gas productions were higher with hB than with oat (Pb0.05). Differences were also found
between hB for total gas production, lag time and rate of degradation (Pb0.01). The production
of SCFA was also higher with hB (6.1 mMol/g DM incubated; Pb0.05) than with hulled barley
and oat (4.9 and 2.9 mMol/g DM incubated respectively). In contrast, oat generated higher
ammonia (Pb0.05) production (1.4 mMol/g DM incubated, on average) than both hB and HB
(1.0 mMol/g). In conclusion, hB are better fermented, produce more beneficial (SCFA) and less
harmful (ammonia) metabolites and have a better potential than other cereal species to
modulate gut microbiota and improve gut health.