THE EFFECT OF SODIUM-HYDROXIDE AND ALKALINE HYDROGEN-PEROXIDE ON CHEMICAL-COMPOSITION OF WHEAT-STRAW AND VOLUNTARY INTAKE, GROWTH AND DIGESTA KINETICS IN STORE LAMBS

Wheat straw was treated with alkaline hydrogen peroxide (AHP) by eithe r spraying (spray AHP, E) 250 ml of AHP solution containing 20 g H2O2 and 8.3 g NaOH kg(-1) straw dry matter (DM) or by soaking (dip AHP, F) straw in 2% AHP solution to give a final concentration of 57 g H2O2 a nd 19 g NaOH kg(-1) DM, The AHP-treated straws were compared with A, B , C and D straws treated respectively with 0, 8.3, 25 and 50 g kg(-1) DM of NaOH alone in a feeding trial using 36 Dorset Down x Mule store lambs. A digestibility trial using 7 wethers, selected from the feedin g trial, in a 7 x 4 incomplete Latin square was also conducted to exam ine the effects of these treatments on the extent of nutrient digestio n and rates of passage (k(1) and k(2)). Neutral-(NDF), Modified acid-( MADF), Acid-detergent fibre (ADF) and Acid-detergent lignin (ADL) in t he straw organic matter (OM) changed quadratically with increasing NaO H alone from 0 to 50 g kg(-1) DM. AHP had different effects on composi tion depending upon the mode of application. Spray treatment (E v B) d id not alter composition but the dip treatment F had less NDF and more MADF, ADF and especially ADL than treatment C. Voluntary straw intake (VSI), liveweight gain (LWG), LWG/W-0.75 and digestibility increased linearly (P < 0.001) with the increase in NaOH alone from 0 to 50 g kg (-1). Spray AHP did not affect VSI, LWG or digestibility compared with either untreated straw or straw treated with the same amount of NaOH alone. Dip AHP tended to increase (P > 0.05) VSI, LWG and LWG/W-0.75 b ut decreased DM, MADF (P < 0.05), OM (P < 0.01) and NDF (P > 0.05) dig estibility compared with untreated control and reduced VSI, LWG and LW G/W-0.75 (P < 0.05) and all digestibility parameters (P < 0.001) compa red with treatment with NaOH alone (C), Spray AHP treatment increased (P < 0.05) rate of passage (k(1) measured with Yb) compared with NaOH- treated control. Dip AHP treatment showed a similar trend (P > 0.05). AHP did not result in any gross ill effects on animal health.