Poster 6.3: Voluntary intake and digestibility of treated oil palm fronds - M. Wan Zahari, S. Oshio, D. Mohd Jaafar, M.A. Najib, I. Mohd Yunus and M.S. Nor Ismail

INTRODUCTION

Oil palm frond (OPF) is one of the most abundant agricultural by-products in Malaysia. Almost all pruned fronds are discarded in the plantation, mainly for nutrient recycling and soil conservation. OPF has great potential for use as a roughage source or as a component in compound feed for ruminants. Much research has been carried out by MARDI and JIRCAS on use of OPF for animal feeding, either fresh, or processed as silage or pellet (Abu Hassan, Ishida and Mohd Sukri, 1995). Detailed studies on the fermentation characteristics and palatability of OPF silage, as well as on animal performance, have been reported (e.g. Abu Hassan and Ishida, 1991; Ishida and Abu Hassan, 1997; Oshio et al., 1999). The objective of this trial was to study the effect of processing methods of OPF on its digestibility and voluntary intake.

MATERIALS AND METHODS

Four processing methods for OPF (pelleting, dry chopping, silage, and NaOH treatment) were compared for in vivo digestibility and intake using 16 Kedah-Kelantan (KK) cross yearling heifers (mean liveweight 160 kg). The fresh OPF collected from the UPM farm in Serdang, Selangor, Peninsular Malaysia, was chopped to 2-3 cm length and blended uniformly. A portion of the chopped OPF was directly packed in plastic drums (approximately 100 litre) for making silage. The material was kept for one month before feeding to the animals.

Simultaneously, a portion of the chopped OPF was mixed with 10% NaOH solution at the ratio of 15 kg NaOH to 100 kg of fresh OPF. The material was packed similarly in the drums and kept for one month until feeding. For making dry chopped OPF, a portion of the chopped OPF was chopped again using the same machine, dried under the sun for one day, and then completely dried in an oven. OPF pellets were produced with a 12-mm diameter pelletizer after being dried the same way as chopped OPF, and were ground through a 4-mm screen grinder.

These four types of OPF were mixed at various ratios with a basal ration comprising 50% palm kernel cake (PKC), 20% palm oil mill effluents (POME), 16% tapioca waste, 10% rice bran, 2% minerals and vitamin mixture, 1% salt, and 1% urea. Rations consisting of 40% and 60% OPF pellets, 40% chopped OPF, 40% OPF silage and 40% NaOH-OPF were used to measure the apparent digestibility of each form of treated OPF at maintenance level, with 3-4 animals for each ration. Each ration was fed for 14 days and faeces from each animal were collected for measuring the digestibility throughout the last 5 days. OPF pellets and chopped OPF were mixed at the ratio of 25, 40, 60 and 75% of the total feeds on DM basis with the basal ration, as mentioned above. Each diet was voluntarily fed to each group of 3-4 heifers. OPF silage and NaOH-treated OPF were also mixed with the basal ration and were fed to the animals in the same ratios, except the 75% rations. Each ration was fed to the animals daily at 10-20% above the saturation level for 9 days. The weight and DM content of the remainder were measured in the morning. Collection of faeces was carried out for the last 3 days to measure the digestibility.

RESULTS AND DISCUSSION

Table 1 outlines the voluntary intake and digestibility of the treated OPF rations. At maintenance level, the digestibility of OPF pellets was the lowest. The intake of OPF pellets mixed with the basal ration was maintained even at the 75% inclusion level. While chopped OPF and OPF silage did not reveal much difference in digestibility, intake was higher for the chopped OPF ration than for OPF silage. Nevertheless, the intake at 75% level of chopped OPS was depressed to 58% of that at the 25% level.

Table 1. Voluntary intake and digestibility of treated OPF rations

The digestibility and intake of NaOH-treated OPF were the highest. Although grinding and pelletizing lowered the digestibility, due to the faster rate of passage through the rumen, these processes were more effective for enhancing the intake. At the same time, NaOH treatment improved not only the digestibility but also the intake remarkably.

Therefore, this treatment has great potential for improving OPF quality. However, as NaOH is caustic and dangerous, a safer and more cost-effective procedure for treatment is needed. Ammonia treatment, an alternative to NaOH treatment, was not carried out in this experiment. Although ammonia treatment could be adopted for improving frond quality, there is a high possibility that reaction between soluble sugars in OPF and ammonia will produce toxic substances, such as 4-methylimidazole. Thus, if ammonia treatment is adopted for improving the quality, it will be important to identify the occurrence of toxic materials.

CONCLUSION

The digestibility and intake of NaOH-treated OPF were higher than those of chopped OPF or OPF silage. More studies are needed to determine if NaOH treatment is suitable, or can be replaced with ammonia, for improving OPF quality. Intake was lower for OPF silage than for chopped OPF, but the digestibility was comparable. Compared to fresh-chopped OPF, OPF silage has advantages for animal feeding, in terms of ease of handling, storage, less labour usage, easy to transport, etc. Fresh chopped OPF needs to be processed daily. This is not only time-consuming but in the long-term it is not practical and not cost-effective.

Although pelletizing of OPF is effective for improving intake, it depressed the digestibility. Therefore, an alternative processing method such as cubing is required to maintain the same level of digestibility as chopped OPF and simultaneously to improve the intake.

REFERENCES

Abu Hassan, O., Ishida, M., & Mohd Sukri, I. 1995. Oil palm fronds (OPF) technology transfer and acceptance, a sustainable in situ utilization for animal feeding. p. 134-135, in: Proceedings of the 17th Malaysian Society of Animal Production (MSAP) Annual Conference. Penang, 28-30 May 1995.

Abu Hassan, O., & Ishida, M. 1991. Effect of water, molasses and urea addition on oil palm frond silage quality. - Fermentation characteristics and palatability to Kedah-Kelantan bulls. p. 94, in: Proceedings of the Third International Symposium on the Nutrition of Herbivores, Penang, Malaysia, 25-30 August 1991.

Ishida, M., & Abu Hassan, O. 1997. Utilization of oil palm fronds as cattle feed. Jap. Agric. Res. Quarterly, 31: 41-47.

Oshio, S., Wan Zahari, M., & Mohd Jaafar, D. 1999. Feed evaluation for quality control of oil palm fronds as a ruminant feed after pruning. MARDI-JICA Publication, No.7.