Intake, digestibility and nitrogen balance in sheep fed diets containing detoxified castor cake1

Abstract

The effect of substituting soybean meal (SM) with four levels (0, 33, 67 and 100%) of detoxified castor cake (DCC) on intake, nutrient digestibility and nitrogen balance was evaluated in uncastrated, male, crossbred sheep in a randomised complete block design with four treatments and five replications. There was a decreasing linear effect from the levels of substitution on dry matter (DM), organic matter (OM) and crude protein (CP) intake, total carbohydrates (TC), non-fibrous carbohydrates (NFC) and total digestible nutrients (TDN), and on DM, OM and TC digestibility, for reductions of 2.04, 1.70, 0.35, 1.56, 1.89 and 1.67 g dia-1 and 0.34, 0.53 and 0.51 g kg-1 DM respectively, for each 1% SM substituted with DCC. DMI and NDFap expressed, in %BW and g kg-0.75, showed a quadratic response, with a maximum value of 3.85 and 1.73%BW, and 95.15 and 42.47 g kg-0.75, for 25.00, 65.00, 20.75 and 61.50% SM substituted with DCC respectively. There was a linear increase in the intake of acid detergent fibre and in ether extract digestibility. The nitrogen balance was not affected by the substitution of SM with DCC. Substituting soybean meal with castor cake detoxified by autoclaving in lamb diets alters nutrient intake and digestibility without affecting the nitrogen balance.