In vitro gas production measurements and estimated energy value and microbial protein to investigate associative effects of untreated or biological treated linen straw and berseem hay

An in vitro gas production technique was used to investigate the associative effects of untreated or biologically-treated linen straw with berseem hay (H). The linen straw (LS) was biologically treated with white rot fungi (TLS). Ground samples (200 mg DM) of H, LS, TLS and the mixtures (50% w/w) of H + LS and H + TLS were incubated in 100 ml glass syringes with buffered rumen fluid. Cumulative gas production was recorded at 3, 6, 9, 12, 24, 48, 72 and 96 h of incubation and the kinetics of gas production was described by using the equation Gas (t) = b [1 – exp (–c (t – L))]. Gas production volume was highest for hay (P < 0.05) and greater for H + LS (P < 0.05) than LS and TLS. Total gas production at 96 h and rate of gas production increased when LS or TLS were mixed with hay. Metabolizable energy (ME) and net energy (NE) were higher (P < 0.01) for H, H + LS and H + TLS than for LS and TLS. Organic matter digestibility (OMD %) and microbial protein production were significantly higher for H, H + LS and H + TLS than for LS or TLS. In conclusion, positive associative effects on in vitro gas production occurred more consistently when untreated and biologically-treated linen straw was incubated in mixtures with hay.