Evaluation of silages from hybrid m734 of sunflower obteined in diferent cutting times using the semi-automated "in vitro" gas production technique

Abstract

The success on sunflower utilization for ensiling is dependent on the correct cutting time during growing season. The objective of this experiment was to evaluate, by using the in vitro gas production technique, "Reading Pressure Technique", the kinetic of organic matter (OM) and dry matter (DM) of silages from the sunflower hybrid M734 obtained at 100, 107, 114 and 121 days after planting. Headspace gas pressure readings were taken at 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 and 96 hours post-inoculation. An unicompartimental mathematical model was applied to describe the profiles in terms of the potential gas production, lag phase, rate of gas production and effective dry matter degradation which used 2, 5 and 8%/h rate of passages. It was observed that latter cuttings promoted the reduction on the potential of gas production for OM (162, 155, 144 and 139 mL) and DM (138, 129, 121 and 119 mL); increased of "lag phase" for OM (2,4, 2,5, 2,8 and 2,9 h) and DM (2,46, 2,54, 2,98 and 2,99 h); and reduction of rate fermentation for OM (0,023, 0,022, 0,017 and 0,017 mL/h) and DM (0,022, 0,020, 0,015 and 0,016 mL/h) respectively for 100, 107, 114 and 121 days after planting . The best cutting time for M734 hybrid were at 100 and 107 days after planting.