Effect of different heat processing methods on nutritive value of common vetch seed in ruminants

The present study was carried out to study different methods of heat processing on nutritional value of vetch seed. Vetch seed was processed by steam flaking, roasting and microwaving. Dry matter degradability was determined using nylon bags at 0, 2, 4, 8, 12, 24, 36, 48 hours of ruminal incubation. Vetch seed processing, affected dry matter degradability so that steam flacked and roasted samples had the highest and lowest degradability percentage respectively (91.06 vs 70.49, P<0.05). The crude protein degradability showed the same pattern as well (91.64 vs 57.52 percent for steam flaked and roasted vetch respectively, P<0.05). Five different digestibility models were used to interpret degradability of dry matter and protein of raw and heat processed vetch seed. Ørskov and McDonald's model with lag time was the best fitted model for dry matter degradability of raw, steam flaked and roasted vetch seed and Franc model was the best fitted model for microwaved vetch. Considering the crude protein degradability, the best fitted model were Dhanoa without delay phase for the raw and steam flaked vetch, Ørskov and McDonald's with lag time for roasted vetch, and Dhanoa with lag time for microwaved vetch, respectively. Steam flaked and microwaved vetch had the greatest and lowest gas production during 48 hours incubation (184.96 vs 141.84 ml respectively, P<0.05). Roasting increased metabolizable energy of vetch (4.82 vs 5.53 MJ/kg DM for raw and roasted vetch respectively, P<0.05), however no changes was observed in ME content of vetch with microwave or steam flaking.