Effect of harvest stage on the chemical composition, in vitro gas and methane production of Bituminaria bituminosa

The aim of the current experiment was to determine the effect of harvest stage on the chemical composition, in vitro gas and methane production, organic matter digestibility and metabolisable energy of Bituminaria bituminosa. After determination of chemical composition, Bituminaria bituminosa hay was subjected to the test of in vitro gas production. The metabolisable energy and organic matter digestibility of Bituminaria bituminosa hay were determined using the gas production at 24 h incubation. Harvest stage had a significant effect on the chemical composition of Bituminaria bituminosa hay. Dry matter, neutral detergent fiber and acid detergent fiber contents of Bituminaria bituminosa hay increased while crude ash, crude protein contents and relative feed value decreased with advancing maturity. Dry matter, neutral detergent fiber, acid detergent fiber, condensed tannin and relative feed value of Bituminaria bituminosa hay ranged from 20.1 to 33.9 %, 45.0 to 66.1 %, 25.8 to 42.5 %, 0.96 to 1.25 % and 78.3 to 141.85 respectively. On the other hand, crude ash and crude protein of Bituminaria bituminosa hay ranged from 7.96 to 9.51 and 14.2 to 23.6% respectively. In vitro gas production, methane production (as ml), metabolizable energy and organic matter digestibility of Bituminaria bituminosa hay ranged from 41.8 to 50.4 ml, 6.95 to7.70 ml, 9.28 to 11.0 MJ kg-1 DM and 63.6 to76.5 % respectively and decreased with increasing maturity whereas the percentage of methane increased with increasing maturity. Although the inevitable loss in nutritive value of Bituminaria bituminosa plant with advancing maturity, even at the seeding stage, Bituminaria bituminosa plant could provide hay of acceptable quality for ruminant animals to meet their requirements. In addition, low level of condensed tannin in Bituminaria bituminosa offers an opportunity to decrease the risk of bloat for grazing ruminant animals. But this needs verification with further testing