EFFECT OF BIODEGRADATION PERIOD ON THE CHEMICAL COMPOSITION

ABSTRACT

Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process. Hence, this study was to determine the; effect of biodegradation period on the chemical composition in vitro gas production and dry matter digestibility and post in vitro parameters of  rice straw and mixture. The moisture content of rice straw (RS) and palm oil sludge was adjusted to 75% using sterilized water. The rice straw and palm oil sludge mixture was thereafter loaded into a 35cl of sterilized bottles, it was then corked with cotton wool and covered with foil paper. This was done in replicate. The bottles were sterilized cooled and inserted with Pleurotus tuber-eruguim spawn. Biodegradation was carried out for 8 weeks and sampled at every 2weeks.  The dry matter (DM %) values for (RS1 and POS mixture at ratio 10:90)  was not different significantly among the various weeks, but the highest value was in 4 weeks (96.75%) and the least in 8 weeks (96.75%). RS2 (palm oil sludge), the DM value shows slight significant difference and the only difference was observed in 2 weeks while others were the same as compared with the control (0%).The crude protein (CP %) at RS1 shows no variation significantly. The CP values which ranges from 6.125% to 3.500% was in 2 weeks and 4 weeks and was least in 6 weeks. While at RS2 there was significant variations among the periods, although the highest CP value was in 2 weeks (14.88%) and the least was in 6 weeks (7.00%). The CH₄ (ml) at RS1 and RS2 inclusion level showed no significant variations among the period of degradation. The OMD value which ranges from 45.20 in 6 weeks to 48.73 in 2 weeks at RS1 was not significantly influenced. But at RS2, the values which ranges from 49.78 in 6 weeks to 57.83 in 0 and 2 weeks were significantly different. In conclusion, biodegradation with Pleurotus tuberregium (Fr. Songer) increased in the CP and ash contents of rice straw (RS1, RS2) as a result of the proliferation of fungi mycelia strain differences, length of fermentation and the physiological behaviour of the fungi.  There was no variation in the methane volume, metabolizable energy, short chain fatty acids when RS1 and RS2 was subjected to biodegradation.