Effect of extrusion cooking deoiled salseed meal on the utilization of nutrients by sheep

Abstract

Deoiled salseed meal (DSSM) moisturised to 30% was processed in an S-40 L cooker—extruder using a 6 mm die, a screw speed of 350 rpm and an operating temperature of 120°C. The drive controlling the feeder rate was operated at 15 rpm. The extruded product was evaluated in vitro and in vivo. Extrusion cooking increased (P < 0·01) the swelling potential by 1·5-fold and the reducing activity by 2·76-fold and decreased the total tannin content by 0·26% units. Two complete rations with unprocessed and extruded DSSM were formulated and evaluated using twelve Nellore brown ram lambs in a 77-day growth trial. Extrusion cooking had no effect on the feed or dry matter intake (grams of dry matter consumed per (kilogram of weight) 0·75 per day), the average daily gain or the feed: gain ratios. Metabolism trial data revealed that extrusion cooking increased (P < 0·05) ether extract digestibility but N retention, expressed as per cent of absorbed N, was not affected. In a replicated 3 × 3 latin square nitrogen balance experiment, six Nellore ram lambs were given a basal ration, basal ration + unprocessed DSSM or basal ration + extruded DSSM. Extrusion cooking significantly increased ( P < 0·05) NFE digestibility by 26%. A negative crude protein digestibility (−31·51%) was observed for unprocessed DSSM compared with 11·57% for the extruded DSSM. Extrusion cooking increased the energy value by about 23%. Extrusion cooking DSSM appeared to be a quite promising method for improving the utilization of nutrients by sheep.