Table 4.

Effects of dietary xylanase addition on fecal volatile fatty acid concentrations in weaned pigs fed wheat–soybean meal-based diets ¹.

Item	PC	NC	Xylanase, XU per kg Feed				SEM	p-Value 2
			900	1800	3600	7200		Linear	Quadratic	PC × NC	PC × 900 to 7200	NC × 900 to 7200
VFA, mmol/L
Acetic C2	35.00	28.53	30.47	35.45	28.65	30.39	2.844	0.94	0.589	0.115	0.175	0.399
Propionic C3	11.20	9.470	9.630	10.22	9.050	9.360	0.882	0.727	0.986	0.172	0.094	0.923
Iso-Butyric iC4	0.660	0.550	0.650	0.480	0.590	0.740	0.131	0.282	0.529	0.583	0.710	0.679
Butyric C4	6.520	4.800	5.030	5.590	4.310	5.040	0.648	0.89	0.797	0.068	0.033	0.795
Isso-Valeric IC5	0.540	0.460	0.590	0.410	0.400	0.600	0.093	0.436	0.213	0.539	0.656	0.672
Valeric C5	1.600	1.270	1.380	1.300	1.420	1.650	0.176	0.140	0.796	0.185	0.301	0.400
Caproic C6	0.110	0.070	0.110	0.130	0.100	0.130	0.026	0.230	0.725	0.333	0.975	0.121
Total VFA	55.62	45.14	47.86	53.58	44.71	47.90	4.244	0.984	0.759	0.088	0.101	0.482
VFA, % of total
Acetic C2	62.89	63.09	63.36	66.35	62.74	63.79	1.37	0.944	0.698	0.918	0.519	0.530
Propionic C3	20.39	21.15	20.24	19.00	22.29	19.41	1.403	0.703	0.611	0.703	0.986	0.561
Iso-Butyric iC4	1.120	1.230	1.450	0.960	1.220	1.530	0.240	0.403	0.371	0.739	0.543	0.827
Butyric C4	11.58	10.56	10.42	10.18	9.260	10.40	0.713	0.752	0.218	0.317	0.077	0.539
Isso-Valeric IC5	0.920	1.020	1.040	0.820	1.080	1.240	0.179	0.266	0.544	0.702	0.541	0.884
Valeric C5	2.920	2.810	2.930	2.440	2.620	3.360	0.274	0.154	0.123	0.785	0.780	0.931
Caproic C6	0.190	0.140	0.200	0.240	0.320	0.270	0.063	0.185	0.179	0.570	0.528	0.100

¹ Positive control (PC): a wheat/soybean meal-based diet formulated to meet pig requirements (NRC, 2012) except for energy (−50 kcal ME from the requirement to avoid over formulation due to ingredient variation). Negative control (NC): PC diet with reduction of 100 kcal of ME. Xylanase was included at 30, 60, 120, and 240 g/ton in negative control diets to create 4 additional dietary treatments consisting of xylanase addition at 900, 1800, 3600, and 7200 U/kg feed, respectively (CJ Bio America INC, 2001 Butterfield Road, Suite 720, Downers Grove, IL 60515, USA). ² Contrast: positive control vs. xylanase addition (900 to 7200 XU/kg); negative control vs. xylanase addition (900 to 7200 XU/kg); positive control × negative control.