Butyrate is the SCFA responsible for augmenting structural aspects of intestinal adaptations by increasing proliferation and decreasing apoptosis within 4 hours postresection. The intestinotrophic mechanism(s) underlying butyrate's effects may involve GLP-2. Ultimately, butyrate administration may enable an infant with short-bowel syndrome to successfully transition to enteral feedings by maximizing their absorptive area.

Cultivation-independent microbial molecular ecology approaches were used to examine the effects of antibiotic growth promoters on the pig ileal microbiota. Five-week-old barrows were fitted with a simple T-cannula at the distal ileum. Three diets meeting or exceeding the minimum nutrient requirements were fed for 5 wk and supplemented as follows: 1) negative control (no antibiotic; n = 5), 2) continuous tylosin administration (n = 5), and 3) an antibiotic rotation sequence (wk 1, chlorotetracycline sulfathiazole penicillin; wk 2, bacitracin and roxarsone; wk 3, lincomycin; wk 4, carbadox; wk 5, virginiamycin; n = 5). Ileal luminal contents were collected for DNA isolation at the end of each of the 5 wk of the testing period. The V3 region of 16S rDNA was amplified by PCR and analyzed via denaturing gradient gel electrophoresis (DGGE) and quantitative polymerase chain reaction (qPCR). Resulting PCR-DGGE band numbers (bacterial species) were counted, and the banding patterns analyzed by calculating Sorenson's pairwise similarity coefficients (C(S)), an index measuring bacterial species in common among samples. Band numbers and total bacterial DNA concentrations decreased (P < 0.05) temporally in antibiotic-treated pigs compared with controls. Comparisons between treatments yielded low intertreatment C(S) indices, indicating treatment-dependent alterations in banding patterns, whereas intratreatment comparisons revealed increased homogeneity in antibiotic-treated vs. control pigs. Sequence analysis of treatment-specific bands identified three Lactobacillus, one Streptococcus, and one Bacillus species that were diminished with antibiotic rotation treatment, whereas tylosin selected for the presence of L. gasseri. Lactobacillus-specific qPCR was performed and analyzed as a percentage of total bacteria to further evaluate the effects of antibiotic administration on this genus. Total bacteria were decreased (P < 0.05) by tylosin and rotation treatments, whereas the percentage of lactobacilli increased (P < 0.05) by d 14 and through d 28 in tylosin-treated pigs. The decrease in total bacteria by antibiotics may reduce host-related intestinal or immune responses, which would divert energy that could otherwise be used for growth. Conversely, the ability of tylosin to improve animal growth may relate to its apparent selection for lactobacilli, commensals known to competitively exclude potentially pathogenic species from colonizing the intestine.

Fourteen ileally cannulated pigs (BW = 35 +/- 2 kg) were randomly allotted to a replicated 7 x 7 Latin square design experiment to evaluate the influence of the soybean oligosaccharides (OS), raffinose and stachyose, on ileal nutrient digestibility and fecal consistency. Semipurified diets containing soy protein concentrate (SPC) or soybean meal (SBM) as the sole protein sources were fed. Soy solubles (SS), a by-product of SBM processing containing 3.5% raffinose and 11.5% stachyose, were used to increase dietary raffinose and stachyose concentrations. The seven dietary treatments were SPC, SPC + 9% SS, SBM, SBM + 9% SS, SBM + 18% SS, SBM + 24,000 U alpha-galactosidase enzyme preparation/kg diet, and a low-protein casein (LPC) diet used to calculate true digestibility. Diets, with the exception of the LPC diet, were formulated to contain 17% CP. All diets contained 0.5% chromic oxide as a marker for ileal digestibility determination. The experimental periods were divided into a 5-d diet adaptation followed by 2-d of ileal digesta collection. Diets and digesta were analyzed for DM, N, Cr, amino acids (AA), raffinose, and stachyose. Fecal consistency was determined on d 6 and 7 of each experimental period. The apparent and true ileal AA digestibilities were not different (P < 0.05) for the SPC and SBM control diets. When SS was added to the SPC diet, apparent and true N and AA digestibilities were depressed (P < 0.05) with the exception of Trp and Pro. The apparent and true ileal N and AA digestibilities were not different (P > 0.05) between the SBM control and SBM + 9% SS diets with the exception of Glu. There was a linear decrease (P < 0.05) in apparent and true DM, Val, Gly, and Tyr digestibilities when increasing levels of SS were added to the SBM diet. The addition of alpha-galactosidase did not improve apparent or true ileal N or AA digestibilities except for apparent and true Val and Tyr. Ileal raffinose digestibility was improved (P < 0.05) by addition of a-galactosidase, but was not affected by any other dietary treatment. Ileal stachyose digestibility was not affected (P > 0.58) by treatment. Fecal consistency likewise was not affected (P > 0.36) by dietary treatment. In conclusion, soy OS reduced nutrient digestibilities, but the reductions were small, ranging from approximately 1.1 to 7.4 percentage units. This suggests that other factors may be negatively impacting SBM digestibility.

The nutritional regulation of intestinal adaptation extends beyond the route of nutrient administration as specific nutrients are known to mediate the adaptive response. Dietary carbohydrates are known to enhance intestinal adaptation in patients with short-bowel syndrome. This review discusses SCFA-induced adaptation in intestinal structure and function in adult rat and neonatal piglet models. Potential mechanisms relate to the salvage of energy as SCFA in the colon, direct mediation of intestinal adaptation by SCFA and stimulated release of glucagon-like peptide-2 (GLP-2) from enteroendocrine L cells by SCFA. Among the produced SCFA, butyrate appears to be responsible for increasing plasma GLP-2 concentration, in addition to the enterotrophic effects. Emerging evidence reveals that physiological concentrations of butyrate acutely upregulate the expression of key enterocyte-associated nutrient transporters. Focused experiments are needed to carefully identify the critical components of intestinal adaptation and yield conclusions regarding the relative contributions of SCFA and GLP-2 during the various phases of this process.

Specific pig breeds with unique characteristics have been developed, and the current study sought to characterize some of these differences. Using modified Ussing chambers, electrophysiological mucosal transport of D-glucose, L-Gln, L-Pro, L-Arg, L-Thr, and glycylsarcosine was assessed in small intestinal tissues (duodenum, jejunum, ileum) taken from Yorkshire-based hybrid (BW = 142.4 +/- 2.0 kg; mean age = 8 mo) and Meishan (BW = 65.8 +/- 0.8 kg; mean age = 6 mo) female pigs after 4 h of lipopolysaccharide (LPS) exposure. Gilts were randomly assigned to control (saline infusion; n = 6 Yorkshires, n = 5 Meishans) or LPS (n = 7 Yorkshires, n = 5 Meishans) groups. Therefore, treatments were arranged in a 2 (breed) x 2 (LPS infusion) factorial. Four hours after infusions, pigs were euthanized, and intestinal segment samples were removed. Glucose transport in the ileum was decreased (P < 0.001) in Yorkshires with LPS but was increased (P < 0.001) by over 2-fold in Meishans with LPS. After LPS infusion, Pro transport was increased in duodenum (over 5-fold; P = 0.04) and ileum (over 10-fold; P < 0.001) of Meishans but was unaffected in Yorkshires. Arginine transport in the ileum of control Meishans was greater (P = 0.05) than Arg transport in control Yorkshires. Glycylsarcosine transport was greater (P = 0.02) in Meishans than Yorkshires (nearly 2-fold), regardless of LPS provision. Glycylsarcosine transport was increased (P = 0.003) over 2-fold by LPS, regardless of pig breed. Resistance (barrier function) was increased (P = 0.03) by LPS in Yorkshires but was unaffected in Meishans. The current study indicates that small intestinal function responded differently to LPS in Yorkshire and Meishan gilts and that these effects were nutrient- and segment-dependent.