Palm press fibre is a bulky feed that cannot be consumed in its raw form by ruminants in amounts adequate to support profitable production (Jalaludin, 1996). It is acceptable to ruminants only at a low level of inclusion and early studies concluded that the optimal level of palm press fibre inclusion was 10%. Crude protein and crude fibre digestibility decreased when the inclusion rate exceeded 25-30% (Göhl, 1982; Devendra, 1985). Supplementation with a protein source, including a relatively poor one like palm kernel meal, is necessary (Devendra, 1985). The fibre can be dried and pelleted to overcome the problems of poor keeping quality and bulkiness (Göhl, 1982).
Because the potential for using palm press fibre for ruminant production is important, there have been several attempts to enhance its nutritive value by chemical treatment (urea, ammonia, NaOH) and by manipulating the ration to optimise rumen fermentation (Jalaludin, 1996).
Examples of diets based on palm press fibre
In Malaysia, with crossbred cattle fed with various palm kernel meal:palm press fibre ratios (90:10, 70:30, 50:50), the highest daily growth (563 g/d) was reported for the lowest inclusion (10%) of palm press fibre (Hutagalung et al., 1986). A diet based on oil palm by-products (palm kernel cake 30%, palm press fibre 15%, palm oil mill effluent 18%, molasses 35% plus urea and minerals) met the nutritional requirements of dairy cattle (Shibata et al., 1988a; Shibata et al., 1988b). Palm oil mill effluent and press fibre combined in equal proportions can constitute up to 50% of the cattle ration but this blend should not be stored for more than 36 hours as it rapidly becomes unpalatable (Göhl, 1982). Buffaloes increased their voluntary intake of palm press fibre (360 g/day) when it was sprayed with molasses and supplemented with fish meal (Jalaludin, 1996).
Effects of treatments on digestibility, degradability and intake
In vitro OM digestibility of palm press fibre is extremely low (15-20%), although defatting increased it (up to 26-32%), as did treatment with 5% NaOH (29-35%). However, these levels were below the digestibility required in a viable feedstuff (Obese et al., 2001). Intensive steaming and explosive depressurization increased OM digestibility up to 42 and 52% respectively (Shibata et al., 1988b). In another trial DM digestibility increased from 43% to 58% when palm press fibre was treated with 8% NaOH (Jelan et al., 1986). In an earlier trial, however, chemical treatment using NaOH or Ca(OH)2 did not improve digestibility of crude fibre in palm press fibre due to the formation of soaps (Devendra, 1985).
Palm press fibre is poorly degradable in the rumen. In both an in sacco study and a fermentation study carried out with rumen fluid, palm press fibre, raw or treated with ammonia, were among the less degradable and fermentable materials tested, which included palm kernel cake, Guinea grass (Megathyrsus maximus), coconut waste and rice straw (Ho et al., 1994). The 48h rumen disappearance of DM and crude fibre were also much lower for palm press fibre (18-22% and 11-12% respectively) than for palm kernel meal and palm oil sludge (Shibata et al., 1988b; Vadiveloo et al., 1992). The rumen degradability potential of palm press fibre silage was improved by supplementing with a urea-molasses mixture (Kositkajorndet et al., 2009).
Buffaloes fed urea-treated palm press fibre had significantly higher voluntary feed intake when a supplement of both energy and protein was given, compared to those receiving only protein or energy (Jalaludin, 1996). In India, the optimum conditions for effective ammoniation of palm press fibre was 4% urea at 40% moisture for 20 days, which made it suitable as potential substitute for conventional roughages (such as groundnut haulms) to buffalo bull calves (Dayal et al., 2002).