326
Anaerobic digestion of feces from finishing swine fed with diferents levels of soluble fiber
The manure quantity and characteristics depends directly on physiology and health status of pigs and diet composition. As known the nutrient excretion increases when the animal has low feed:gain ratio. How it was expected the use of the soluble dietary fiber promoted significant changes in anaerobic digestion of the feces. This study was conducted to determine the effect of increasing levels of dietary soluble fiber (SF) on the anaerobic digestion of the feces from finishing pigs in qualitative feed restriction program. Twenty-one batch digesters of bench were assigned in a 4 treatments in a complete randomized design with 3 replications for each. The treatments were prepared with feces from animals fed with four different diets that were: control diet (basically composed by corn and soybean meal contained 3229 kcal gross energy, 13.91% crude protein, 1.50% soluble fiber) and three isoproteic diets with purified pectin inclusion to increase the levels of soluble fibers to 4, 8 and 12%, and consequent decrease levels of gross energy. The feces were collected when the animals had 100kg, and mixed with water to obtain a 4% dry matter substrate. The volatile solids (VS) reduction, the biogas and the methane quantity of production and their potential production for the volatile solids and the feces quantity added were evaluated. Statistical analyses were performed using PROC GLM procedure of SAS. There were not differences (P>0.05) for the volatile solids reduction. In other hand there were cubic effect (P<0.05) for the total biogas and methane production, and their potential production. In conclusion the dietetic soluble fiber inclusion showed good potential productions of biogas and methane, probably because of the worst digestibility of the diets and consequently low feed:gain ratio of the animals.
Table 1. Mean values, standard error of the mean and p-value, obtained for the biogas and the methane potential productions of the swine feces fed with diets containing different levels of soluble fiber (SF).
|
Control |
Experimental diets |
|
|
||
|
1,5%SF |
4%SF |
8%SF |
12%SF |
SEM |
P-value |
VS reduction, % |
64,13 |
61,79 |
66,80 |
63,63 |
2,35 |
0,9275 |
Biogás production, m3 |
0,0806 |
0,0440 |
0,0839 |
0,0759 |
0,01 |
0,0097 |
Methane production, m3 |
0,0650 |
0,0363 |
0,0689 |
0,0601 |
0,01 |
0,0131 |
Biogas, (m3.kg-1 added SV) |
1,5669 |
0,8569 |
1,8824 |
1,7002 |
0,13 |
0,0025 |
Methane, (m3.kg-1 added SV) |
1,2631 |
0,7084 |
1,5459 |
1,3445 |
0,10 |
0,0035 |
Biogás, (m3.kg-1 added feces) |
0,3416 |
0,1862 |
0,3554 |
0,3218 |
0,02 |
0,0096 |
Methane, (m3.kg-1 added feces) |
0,2754 |
0,1540 |
0,2919 |
0,2545 |
0,02 |
0,0132 |
Keywords: biogas, methane, pectin