Nutrient Digestibility of the Waste of Saccharification Process From Cassava Bagasse on the Laying Hens

The objective of this research was to study the nutrient digestibility and the metabolizable energyvalue of the waste of saccharification process from cassava bagasse (WSPCB) on the laying hens.Twenty ISA-Brown laying hens at the age of 72 weeks were randomly distributed into three feedingtreatments which consisted of cassava bagase (CB), WSPCB of solid state fermentation method(WSPCB-SSF), and WSPCB of sub merged fermentation method (WSPCB-SmF). All of the hens werefasted for 24 hours and 15 of them were fed with CB, WSPCB-SSF and WSPCB-SmF (five hens foreach test-diet). The other five hens were still fasted. Then, all of the hens were fasted again and theirexcreta were collected during 48 hours. The nutrient digestibilities which were measured consisted ofthe Apparent and True Digestibility of Dry matter (ADDM and TDDM), Crude Fiber (ADCF andTDCF), Starch (ADS and TDS), and the Apparent and True Metabolizable Energy (AME and TME).The result of this research showed that the saccharification process generated the solid waste with thenutrient digestibility value (ADDM, TDDM, ADS, TDS, AME, and TME) which were significantlylower (P<0.05) than those of CB. The crude fiber digestibility value of the WSPCB has an opositephenomenon in which the ADCF and TDCF of WSPCB-SmF were greater than CB. In conclusion, thenutrient digestibility value, except for ADCF and TDCF, of the WSPCB on the laying hens were lowerin value than those CB.


INTRODUCTION
Indonesia has currently faced a sufficiently serious problem which is related to fossil oil fuel, including premium gasoline. The need of the fuel of premium type in 2006 reached 17 million kl out of the need of 70 million kl of oil fuels with the oil fuel subsidy as much as Rp 60.6 trillion (Prihandana et al., 2007). Bioethanol is a type of fuel which is programmed by the government of the Republic of Indonesia to substitute for the premium gasoline.
Bioethanol is the type of ethanol which is made of biomass through a biological process. Bioethanol can derive from the starch, sugar and the cellulose sources of biomass. The raw material of bioethanol which is not in competition against the allocation for food is the agricultural waste of cellulose source, including cassava bagasse (CB).
Cassava bagasse is a solid waste which results from the processing of cassava into tapioca. The production of cassava in Indonesia in 2002 reached the amount of 16.9 million tons. The output of cassava in majority is absorbed into the tapioca industry in such a way that more than1.2 million tons of CB are generated (BPS, 2003). The main nutrient element of CB is carbohydrate (Tisnadjaja, 1996) with high cellulose content of 29% (Ali-Mursyid et al., 2008). Cellulose is a characteristic nutrient which constitutes the cell wall of plants and has the chemical structure of D-glucose polymer with the β-1,4 glycosidic bond (Carlile et al., 2001).
The production of bioethanol from the material of cellulose source is initiated by the cellulolytic saccharification process to hydrolize cellulose into glucose (Atlas, 1997). Biologically the cellulolytic saccharification is a microbial activity to release the cellulase enzymes in degrading and transforming the cellulose into the simple compound of glucose which is easily consumed by microbes (Gianfreda and Rao, 2004). The use of the mutant of Trichoderma AA1 can increase the activities of cellulases (Ali-Mursyid et al., 2007).
The saccharification process goes through the cellulolytic fermentation from CB to generate the solid waste which is potential as the food or the supplement for fowls. The nutritive conversion from a cellulosic matter during the cellulolytic saccharification process can raise the nutritive value of the matter.
The increase of the digestibility of dry matter, protein, and metabolizable energy, in addition to the increase of protein and amino acid contents as well as the decrease of crude fibers and cellulose, occurs in the fermentation of CB by using the mutant of Trichoderma AA1 (Ali-Mursyid et al., 2008).) The significant increase of the digestibility of soluble protein and apparent metabolizable energy almost as much as 100 kcal/kg from the fermentation of CB by using Aspergillus oryzae (Ali-Mursyid and Zuprizal, 2005). Fermented CB can be used as substitute for corn up to 30% without affecting the performance and nutrient digestibility of broiler chicken (Ali-Mursyid et al., 2010).
The objective of this research was to study the nutrient digestibility and the metabolizable energy of the waste of saccharification process from cassava bagasse on the laying hens.

Materials
The experiment was conducted in vivo to the laying hens of ISA-Brown at the age of 72 weeks with the weight ranged 1700 -2000 g by using the total collection method and the wet force feeding technique (Lessire, 1990). The test-diets which were tested consisted of cassava bagase (CB), WSPCB of solid state fermentation method (WSPCB-SSF), and WSPCB of sub merged fermentation method (WSPCB-SmF). Each of the dry test-diet was finely ground, weighed, and then mixed with water in the proportion of 1:2. This test-diet was subsequently fed to the laying hens.

Experimental Design
Twenty hens were randomly arranged into individual battery cage which were equipped with a plastic tray excreta container. The experiment used was the completely randomized design. The treatments consisted of three kinds of test-diets, namely: CB, WSPCB-SSF, and WSPCB-SmF. Each of the test-diets was fed to five hens as a replications.
All of the hens were fasted for 24 hours, then 15 of them were fed with CB, WSPCB-SSF and WSPCB-SmF (five hens for each test-diet) by using the wet force feeding technique. The other five hens were still fasted. The amount of the feedings of the test-diet was 100g for each hen. Subsequently all of the hens were fasted again and at the same time their excreta were collected during 48 hours (Lessire, 1990). The drinking water was administered ad libitum. The collected excreta were dried under the sunlight for three days, separated from the feather and the foot scale of the hen, weighed, ground, and then their nutrient content which included dry matter, crude fiber, starch (Sudarmadji et al., 2004) and gross energy was analyzed.
The measured nutrient digestibility consisted of: the Apparent and True Digestibility of: Dry Matter (ADDM and TDDM in %), Crude Fiber (ADCF and TDCF in %), Starch (ADS and TDS in %), and Metabolizable Energy (AME and TME in kcal/kg). The calculations of nutrient digestibility and metabolizable energy based on Lemme et al. (2004) and Sibbald (1982), respectively. Equations were as shown bellow: NI = Nutrient Intake (in g DM), NE = Nutrient Excrete (in g DM), NEnd = Nutrient Endogenous (in g DM), EI = Energy Intake (in g DM), EE = Energy Excrete (in g DM), EEnd = Energy Endogenous (g DM), and FI = Feed Intake (in g DM).

Statistical analysis
The data were analyzed by using the Oneway analysis of variance with the Duncan's multiple range test as the further test (Ali-Mursyid, 2011).

RESULTS AND DISCUSSION
The saccharification process of CB produced solid waste which nutrient digestibility value (ADDM, TDDM, AME, and TME) were significantly lower than the raw materials of the CB. On the other hand, the saccharification method did not result in any significant difference in either the nutrient digestibility value of the WSPSB (Table 1). Although the SCW-SSF method was not statistically noticeable, it results in the nutrient digestibility levels which were a little lower than those of the SCW-SmF.
The phenomenon which occurs in this research was not in agreement with Ali-Mursyid and Zuprizal (2005) and Ali-Mursyid et al. (2008) which stated that the fermentation of the CB was able to increase ADDM, TDDM, AME, and TME on broiler. The decrease of the nutrient digestibility of this WSPCB was caused by the difference in the harvesting process. The harvesting process from the fermentation of the CB was conducted by Ali- Mursyid and Zuprizal (2005) and Ali-Mursyid et al. (2008) by picking up all of the biomass. In this research, the harvesting process was conducted by fractionating the liquid from the solid matter in such a way that some of the nutrients produce from the saccharification process got dissolved and then separated from the solid waste. The dissolved nutrient generated from the saccharification process, such as protein and amino acids (Ali-Mursyid et al., 2008), glucose (Ali-Mursyid et al., 2007) as well as the nutrient of the cell contents which were released in the fermentation process (Li et al., 2004) went along with the liquid fraction when harvested.
The results of the chemical analysis showed that the crude fiber content of the CB, the WSPCB-SSF and the WSPCB-SmF were 18.40%, 36.26% and 47.22%, respectively. The increasing of crude fiber in the WSPCB was a result of the loss of the nutrient with the liquid fraction at the time of the harvesting. The insoluble fiber contained in the diet causes the transit time of the digesta to decrease in such a way that the action of the digestive enzymes goes down as well (Choct, 2002).
Effect of separation of solid and liquid materials in the harvesting process also resulted in a decreased metabolizable energy of solid waste produced from saccharification, although its gross energy increased if compared to their raw materials. Gross energy of the CB, WSPCB-SSF, and WSPCB-SmF were 3391.86, 3685.61, 3797.33 kcal/kg, respectively.
The saccharification process produced the solid waste with the ADS and TDS which were significantly (P<0.05) lower than those of the raw materials. The digestibility value of crude fiber of the WSPCB have an oposite phenomenon. The saccharification process with the solid state fermentation (SSF) method was not significantly influential on the ADCF and the TDCF whereas that with the sub-merged fermentation (SmF) method significantly (P<0.05) increased the ADCF and the TDCF of the waste which is generated ( Table 2).
The decrease of the digestibility value of starch (ADS and TDS) of the WSPCB was caused by the starch content of the waste which was 50% lower than its raw materials. The result of the chemical analysis indicated that the starch content of the CB, the WSPCB-SSF, and the WSPCB-SmF were 70.55%, 34.47%, and 23.57% respectively. As known, starch is the polysaccharide component which is easily digested by fowls.
Increasing of the digestibility value of the WSPCB is related to the microbial activities during fermentation. The degradation of cellulose into glucose during saccharification involves the complex cellulase enzyme which consists of endoglucanase (EG), cellobiohydrolase (CBH), and β-glucosidase which cooperate synergically (Meittinen-Oinonen et al., 2004). EG functions is to attack the inner side of cellulose and to fractionate the amorphous part (Haakana et al., 2004) which generates the new side with free chain end. This process causes the fibrillary formation of cellulose to become looser.
The difference in the digestibility value of crude fiber of WSPCB-SSF and WSPCB-SmF is related to the growth type of the microbe during saccharification. The Saccharification with the SSF method had lower water activity value (a w ) compared to the SmF method. The low value of a w boosts the sporulation to occur earlier in such a way that the growth of mycelium will stop and the formation of spores will form immediately (Krishna, 2005). The growth of spores in the saccharification process with SSF method was higher than that in the process with SmF method which was opposite from the growth of mycelium. Spores have stronger cell walls compared to those of mycelium in such a way that spores are more difficult to digest.

CONCLUSION
The nutrient digestibility and the metabolizable energy of the waste of saccharification process from cassava bagasse on the laying hens are lower than those of its raw materials, except for the digestibility of crude fiber.   Table 1