Abstract
Eight $12.4{\pm}0.6kg$ initial body weight crossbred barrows were used to determine the effect of soybean galactooligosaccharides on nutrient and energy digestibility, and digesta transit time. Four dietary treatments were utilized in this trial. Treatment one was a corn-soybean meal based diet (SBM) containing raffinose and stachyose at the levels of 0.16% and 0.75%, respectively. Treatment two (control) was a corn-HP300 (soybean concentrate protein) diet. In treatments three and four, 1.1% and 2.2% commercial stachyose was added to the control diet to provide total dietary stachyose at the levels of 1% and 2%, respectively. The soybean galactooligosaccharides (raffinose + stachyose) level in treatment one was slightly lower compared to that in treatment three. Three collection periods were run with two pigs for each treatment/period. There was a 4 d adjustment period followed by a 3 d collection period. The results showed that the nitrogen retention (86.79%) of pigs fed treatment two diet was higher than that of pigs fed treatment one by 5.2% (p<0.05). The nitrogen retention of treatment three was intermediate 83.09%. The apparent fecal digestibility of all amino acids in treatment two was numerically highest, followed by treatments three and four. However, there were no significant difference among groups (p>0.05). The dry matter (DM), organic matter (OM), crude protein (CP), and crude fiber (CF) digestibility numerically decreased as the soybean galactooligosaccharides level increased, but were not significantly different (p>0.05). Chromium content in feces (from the inclusion of 0.3% chromic oxide in the diets) differed among treatments (p<0.05) at 15 h, 18 h, and 21 h after eating. This showed that the digesta transit time was differed significantly among treatments. Treatment four was the shortest, followed by treatment three, SBM and control. The results demonstrated that in the absence of antinutritional factors and soybean antigen protein, inclusion of 1% and 2% stachyose in corn-HP300 diet has no significant effect on the digestibility of DM, OM, CP, CF and amino acids. When the soybean galactooligosaccharide level in diet one and diet three were adjusted to be almost the same, antinutritional factors such as trypsin inhibitor and soybean antigen protein could decrease the nutrient digestibility and nitrogen retention rate of diet. High levels of soybean galactooligosaccharides shortened the digesta transit time in the intestinal tract. This trial suggested that the total level of soybean galactooligosaccharides (stachyose+raffinose) in the weanling piglet diet is better not to exceed 1% when common soybean meal is used as main protein source.