Palatability, digestibility and voluntary intake of processed oil palm fronds in cattle

Preference tests and digestion trials of 4 different types of fronds of oil palm (Elaeis guineensis Jacq.), i.e. oven-dried form, pellets, silage and sodium hydroxide (NaOH)-treated silage, were carried out to analyze the influence of processing methods on the palatability, digestibility and voluntary intake in cattle. These processed oil palm fronds (OPFs) for digestion trials at maintenance level or under ad libitum feeding were mixed with a basal ration, mainly composed of palm kernel cake and fed to Kedah-Kelantan cross cattle. The digestibility of OPFs per se was calculated from the digestibility of the mixed ration and that of the basal ration. The results were as follows; the digestibility of OPF pellets was considerably lower than that of the other types of processed OPFs. However, OPF pellets had a high palatability and the dry matter intake (DMI) of the mixed ration, which includes OPF pellets, was higher than that of the other types of processed OPFs. These findings suggest that OPF pellets could be utilized as a silage additive to increase the dry matter content of crops with a high moisture level. The digestibility and DMI of ensiling OPFs were equivalent to those of oven-dried OPFs and the palatability of ensiling OPFs was high. Ensiling is the most suitable method to preserve OPFs at a low cost and can be recommended to farmers. NaOH-treated silage had a higher digestible DMI than the other types of processed OPFs, although it had a low palatability. It was confirmed that alkali treatment can effectively improve the nutritive value of OPFs. Therefore, introducing alkali treatment to the production of processed OPFs should be promoted if a safe and cost-effective method is to be developed.