The apparent digestibility of palm kernel expeller (PKE) consumed by pasture-fed sheep

Palm kernel expeller (PKE) usage in New Zealand has increased despite little being known about its nutritional role as a supplement in pasture based diets. The chemical composition of PKE is often reported in New Zealand, but the digestibility is not. A digestibility study was conducted with twenty four lambs fed one of four different amounts (0, 15, 30 or 45%) of their dry matter (DM) intake as PKE, plus molasses pellets (PKEM; 90% PKE and 10% molasses) with the remainder of the diet being fresh pasture. Sheep were fed at either maintenance or ad libitum during two experimental periods, that differed in pasture quality. Digestibilities were extrapolated linearly to estimate digestible energy concentration and the apparent digestibility of DM, crude protein, neutral detergent fibre and gross energy at any intakes for a diet consisting of 100% PKEM. Overall, the estimated apparent digestibility of DM, crude protein, neutral detergent fibre and gross energy for PKEM at intakes of 670 and 1,214 gDM/lamb/day were 63.0, 52.0, 67.0 and 64.0%, respectively. The values estimated for digestible energy concentration (MJ/kgDM) of PKEM ranged between 12.4-12.7, from which values for metabolisable energy concentration of 10.2 and 10.5 MJME/kgDM could be calculated.