Feeding fermentable carbohydrates (FC) to weanling pigs may reduce the negative impact of
proteolytic fermentation on gastrointestinal health and function. A total of 144 newly weaned pigs [6.23 kg body weight
(BW); six pens per treatment; six pigs per pen) were used to determine the interactive effects of feeding additional
fermentable protein (FP) and FC on growth performance, gastrointestinal function and intestinal health. Dietary
treatments, based on a 2×2 factorial arrangement, were: (1) basal diet (control); (2) control +10% poultry meal (PM) as
FP source; (3) control +5% beet pulp (BP) as FC source; and (4) control +10% PM and 5% BP. Diets were formulated to
be similar in digestible energy (DE) and digestible amino acid contents. In general, no interactive effects of FC and FP were
observed (P>0.10). During the 3-wk post-weaning period, feeding FP reduced average daily gain (ADG) (242 vs. 269 g
d-1; PB0.05), while FC increased ADG (269 vs. 243 g d-1; PB0.05). Overall, feed intake did not differ between
treatments (P>0.10). On days 14 and 28 post-weaning, Clostridia spp. counts in colon contents, counts of white cells and
segmented neutrophils in blood were lowered (P<0.05) by feeding FC. Blood urea nitrogen was increased by feeding FP (9.5 vs. 6.5 mg dL-1; P<0.05), while ammonia concentration in colon contents was lowered by FC (154 vs. 193 mg mL-1) (P=0.06). Among biogenic amines, levels of tyramine (140 vs. 304 nmol g-1 DM) and spermidine (174 vs. 219 nmol g-1 DM) in colon contents were lowered (P<0.05) by FC. Acetic, proprionic and butyric acid contents in colon contents were increased by feeding FC, while valeric and caproic acid content decreased by feeding FP (P<0.05). Feeding FC and FP had no effect (P>0.10) on colon histology, pH, fecal consistency score and organ weights. Results suggest that FP and FC
have independent effects on newly weaned pigs, while effects appear partly related to changes in gut microbiota.