Microencapsulation protected Lactobacillus viability and its activity in modulating the intestinal microbiota in newly weaned piglets.

Lactobacilli are sensitive to heat, which limits their application as probiotics in livestock production. Lactobacillus rhamnosus LB1 was previously shown to reduce enterotoxigenic Escherichia coli (ETEC) and Salmonella infections in pigs. To investigate its potential in the application, the bacterium was microencapsulated and examined for its survival from feed pelleting and long-term storage as well as its function in modulating pig intestinal microbiota. The in vitro studies showed that freshly microencapsulated Lactobacillus rhamnosus LB1 had viable counts of 9.03 ± 0.049 log10 colony-forming units/g, of which only 0.06 and 0.87 Log of viable counts were reduced after storage at 4 and 22 °C for 427 d. The viable counts of encapsulated Lactobacillus rhamnosus LB1 were 1.06 and 1.54 Log higher in the pelleted and mash feed, respectively, than the non-encapsulated form stored at 22 °C for 30 d. In the in vivo studies, 80 piglets (weaned at 21 d of age) were allocated to five dietary treatments for a 10-d growth trial. The dietary treatments were the basal diet (CTL) and basal diet combined with either non-encapsulated LB1 (NEP), encapsulated LB1 (EP), bovine colostrum (BC), or a combination of encapsulated LB1 and bovine colostrum (EP-BC). The results demonstrated that weaning depressed feed intake and reduced growth rates in pigs of all the treatments during 21 to 25 d of age; however, the body weight gain was improved during 25 to 31 d of age in all groups with the numerically highest increase in the EP-BC-fed pigs during 21 to 31 d of age. Dietary treatments with EP, particularly in combination with BC, modulated pig intestinal microbiota, including an increase in Lactobacillus relative abundance. These results suggest that microencapsulation can protect Lactobacillus rhamnosus LB1 against cell damage from a high temperature during processing and storage and there are possible complementary effects between EP and BC.

Both in vitro and in vivo studies were conducted to verify if the microencapsulation method reported previously could preserve the viability of Lactobacillus rhamnosus LB1 after feed pelleting and long-term storage, and the probiotic functions of the bacterium either alone or in combination with bovine colostrum (BC) in the weaning transition phase of piglets. The results demonstrated that microencapsulation protected Lactobacillus rhamnosus LB1 against cell damage from a high temperature during processing and storage. Dietary treatments with encapsulated LB1, particularly in combination with BC, modulated pig intestinal microbiota, including an increase in Lactobacillus relative abundance during the weaning transition.

Dietary tributyrin intervention improves the carcass traits, organ indices, and blood biomarker profiles in broilers under the isocaloric diets administration.

The objective of the current study was to investigate the effect of dietary tributyrin (TB) intervention on carcass traits, visceral and immune organ indices, and blood biomarker profiles in Arbor Acres (AA) broilers under the isocaloric diets administration. A total of 432-day-old healthy AA broiler chickens were assigned to 4 treatments, with 12 replicates per treatment and 9 birds per cage, for 42 d. The dietary treatments were a basal diet (control) and the basal diet supplemented with a TB product (Eucalorie) at doses of 0.50 g/kg (TB1), 1.0 g/kg (TB2), and 2.0 g/kg (TB3). The results showed that dietary TB treatment quadratically improved the average daily gain and average daily feed intake in the second (22-42 d) and overall (0-42 d) feeding periods (P < 0.05) while decreasing the feed conversion ratio in the second feeding period (P < 0.05). Dietary TB treatment improved the carcass traits, as evidenced by a higher eviscerated carcass rate and lower abdominal fat yield than those in the control group (P < 0.05). The breast meat yield rate was quadratically improved in response to dietary TB administration (P < 0.05). Dietary TB treatment improved the kidney, spleen, thymus, and bursa indices (P < 0.05) and reduced the lung indices compared with those in the control group (P < 0.05). In particular, the spleen and thymus indices were improved quadratically in response to dietary TB administration (P < 0.05). Dietary TB treatment improved the white and red blood cell counts, platelet count, hemoglobin and hematocrit at d 21, and platelet count at d 42 (P < 0.05), with those in the TB3 group being most affected. Dietary TB administration quadratically decreased the plasma content of uric acid at both d 21 and d 42 as well as that of creatine kinase at d 42 (P < 0.05), while it quadratically increased the plasma albumin/globulin ratio at both d 21 and d 42 (P < 0.05). Collectively, these results demonstrated that dietary TB intervention improved the growth performance, carcass traits, selected visceral and immune organ indices, and some blood biochemical markers under the isocaloric diets administration, which may facilitate better economic profit returns in poultry industry application.

Dietary addition of fermented sorghum distiller's dried grains with soluble improves carcass traits and meat quality in growing-finishing pigs.

The fermented sorghum distiller's dried grain with soluble (FS-DDGS) contains numerous nutrients, yet its nutritional effects on growing-finishing pigs remain unclear. The present study evaluated the effects of dietary FS-DDGS addition on growth performance, carcass traits, and meat quality in growing-finishing pigs. A total of 48 healthy male crossbred (Large White × Landrace × Duroc) barrows with initial body weight (BW) of 39.95 ± 2.15 kg were allocated to one of four dietary treatments (12 pigs per treatment). The dietary treatments were as follows: basal diet without (FS-DDGS0 group) or with 50 g/kg (FS-DDGS50 group), 100 g/kg (FS-DDGS100 group), or 150 g/kg (FS-DDGS150 group) FS-DDGS, respectively. Results showed that there were no significant differences in the final BW, average daily gain, average daily feed intake, and feed to gain ratio among these four groups. However, dietary FS-DDGS addition increased (linear, P < 0.05) the pH24h value, contents of ash, crude protein, and proline in Longissimus dorsi muscle, and alanine, arginine, aspartic acid, glutamic acid, isoleucine, leucine, lysine, serine, and tyrosine in Biceps femoris (BF) muscle, when compared with the control group. In addition, dietary FS-DDGS addition decreased (linear, P < 0.05) the drip loss, yellowness (b*) value, and lightness (L*) value, while quadratically improved (P < 0.05) the total bone percentage and glycine and proline contents in BF muscle compared with the control group. Collectively, these findings suggested that dietary FS-DDGS addition could improve the carcass traits and meat quality in growing-finishing pigs although further research is needed to explore the underlying mechanisms.

Dietary Tributyrin Administration Improves Intestinal Morphology and Selected Bacterial and Short-Chain Fatty Acid Profiles in Broilers Under an Isocaloric Feeding Regime.

The current study was conducted to investigate the effect of dietary tributyrin (TB) administration on the intestinal and growth performances in Arbor Acres (AA) broilers under an isocaloric feeding regime. A total of 540 day-old healthy AA broilers were randomly assigned to five treatments with 12 replicates (pens) per treatment and nine birds per pen for 42 days. The dietary treatments were basal diet (control) and basal diet with TB at doses of 0.23 g/kg (TB1), 0.46 g/kg (TB2), 0.92 g/kg (TB3), and 1.84 g/kg (TB4). Particularly, to achieve the isocaloric and cost-saving experimental diets, soybean oil was replaced by the TB product (Eucalorie®) with equivalent metabolic energy contents, and the formulas were rebalanced with zeolite to get the sum of all the feed ingredients to 100%. On days 21 and 42, after weighing, the birds (one bird per replicate) whose body weight was close to the replicate average were euthanized to investigate the effect of dietary TB on intestinal morphology, intestinal bacterial population, and short-chain fatty acid contents. The results revealed that dietary TB administration increased the average daily gain, gain/feed ratio, and European broiler index (P < 0.05) and improved the intestinal morphology (P < 0.05) as indicated by higher villus height and the ratios of villus height/crypt depth in broilers. The incremental levels of TB increased the ileal Lactobacillus content (P = 0.05) and cecal Bacillus content (P = 0.02), respectively. Moreover, dietary TB administration also increased the contents of most of the selected short-chain fatty acids in ileal and cecal digesta (P < 0.05). Collectively, dietary TB administration quadratically improved the growth performance, intestinal morphology, beneficial bacterial population, and short-chain fatty acid levels under the isocaloric feeding regime, indicating better profit return potential in practical poultry operation.

Dietary butyrate glycerides modulate intestinal microbiota composition and serum metabolites in broilers.

Butyrate can modulate the immune response and energy expenditure of animals and enhance intestinal health. The present study investigated changes in the intestinal microbiota composition and serum metabolites of young broilers in response to 3,000 ppm butyrate in the form of butyrate glycerides (BG) via pyrosequencing of bacterial 16S rRNA genes and nuclear magnetic resonance (NMR). The dietary treatment did not affect the alpha diversity of intestinal microbiota, but altered its composition. Thirty-nine key operational taxonomic units (OTUs) in differentiating cecal microbiota community structures between BG treated and untreated chickens were also identified. Bifidobacterium was, in particular, affected by the dietary treatment significantly, showing an increase in not only the abundance (approximately 3 fold, P ≤ 0.05) but also the species diversity. The (NMR)-based analysis revealed an increase in serum concentrations of alanine, low-density and very low-density lipoproteins, and lipids (P ≤ 0.05) by BG. More interestingly, the dietary treatment also boosted (P ≤ 0.05) serum concentrations of bacterial metabolites, including choline, glycerophosphorylcholine, dimethylamine, trimethylamine, trimethylamine-N-oxide, lactate, and succinate. In conclusion, the data suggest the modulation of intestinal microbiota and serum metabolites by BG dietary treatment and potential contribution of intestinal bacteria to lipid metabolism/energy homeostasis in broilers.

Short-term effect of supplemental yeast extract without or with feed enzymes on growth performance, immune status and gut structure of weaned pigs challenged with Escherichia coli lipopolysaccharide.

BACKGROUND: This study investigated the response of piglets receiving a yeast extract without or with a multi-enzyme mixture compared with an antimicrobial growth promoter (AGP) on performance, immune status and gut structure after an E. coli lipopolysaccharide (LPS) challenge. Thirty-six pigs were allotted to six treatments including: a non-challenged control (NCC); LPS-challenged control (CC); CC + AGP; CC + yeast extract; CC + enzymes; and CC + enzymes + yeast extract. On d 7, pigs were bled and thereafter injected with LPS or sterile saline. Blood samples were collected at 6, 48, and 96 h post-challenge. After 96 h post-challenge, pigs were euthanized to obtain duodenal, jejunal and ileal samples. RESULTS: Overall (d 1 to 11), compared with CC pigs, AGP attenuated the LPS-induced reduction in ADG (P = 0.004), ADFI (P = 0.03) and gain/feed ratio (P = 0.01). At 6 h post-challenge, AGP pigs had lower plasma urea N (PUN; P = 0.02) and serum TNF- α concentration (P = 0.07), and higher platelet count (P = 0.04) and serum IL-10 concentration (P = 0.02) than CC pigs. At 48 h post-challenge, AGP pigs had lower PUN (P = 0.02) than CC pigs, whereas enzymes + yeast extract interacted non-additively (P = 0.001) to reduce PUN. At 96 h post-challenge, AGP pigs had lower PUN (P = 0.02) and higher duodenal (P = 0.03), jejunal (P = 0.01) and ileal (P = 0.07) villus height than CC pigs. In addition, enzymes + yeast extract interacted additively and non-additively to reduce ileal IFN-γ (P < 0.0001) and IL-10 (P = 0.012) expression, respectively. Generally, no differences (P > 0.10) were observed between AGP and enzymes + yeast extract pigs on other measured parameters except for the downregulation of ileal IFN-γ (P < 0.0001) and TNF-α (P = 0.003) in enzymes + yeast extract pigs at 96 h post-challenge. CONCLUSIONS: The LPS challenged piglets receiving enzymes + yeast extract showed beneficial responses in gut structure and immunity commensurate with those receiving antibiotics, though the latter had better overall growth performance.

Correction: Transcriptome Analysis Reveals Regulation of Gene Expression for Lipid Catabolism in Young Broilers by Butyrate Glycerides.

[This corrects the article DOI: 10.1371/journal.pone.0160751.].

Transcriptome Analysis Reveals Regulation of Gene Expression for Lipid Catabolism in Young Broilers by Butyrate Glycerides.

BACKGROUND & AIMS: Butyrate has been shown to potently regulate energy expenditure and lipid metabolism in animals, yet the underlying mechanisms remain to be fully understood. The aim of this study was to investigate the molecular mechanisms of butyrate (in the form of butyrate glycerides, BG)-induced lipid metabolism at the level of gene expression in the jejunum and liver of broilers. METHODOLOGY/PRINCIPAL FINDINGS: Two animal experiments were included in this study. In Experiment 1, two hundred and forty male broiler chickens were equally allocated into two groups: 1) basal diet (BD), 2) BG diets (BD + BG). Growth performance was compared between treatments for the 41-day trial. In Experiment 2, forty male broiler chickens were equally allocated into two groups. The general experimental design, group and management were the same as described in Experiment 1 except for reduced bird numbers and 21-day duration of the trial. Growth performance, abdominal fat deposition, serum lipid profiles as well as serum and tissue concentrations of key enzymes involved in lipid metabolism were compared between treatments. RNA-seq was employed to identify both differentially expressed genes (DEGs) and treatment specifically expressed genes (TSEGs). Functional clustering of DEGs and TSEGs and signaling pathways associated with lipid metabolism were identified using Ingenuity Pathways Analysis (IPA) and DAVID Bioinformatics Resources 6.7 (DAVID-BR). Quantitative PCR (qPCR) assays were subsequently conducted to further examine the expression of genes in the peroxisome proliferator-activated receptors (PPAR) signaling pathway identified by DAVID-BR. Dietary BG intervention significantly reduced abdominal fat ratio (abdominal fat weight/final body weight) in broilers. The decreased fat deposition in BG-fed chickens was in accordance with serum lipid profiles as well as the level of lipid metabolism-related enzymes in the serum, abdominal adipose, jejunum and liver. RNA-seq analysis indicated that dietary BG intervention induced 79 and 205 characterized DEGs in the jejunum and liver, respectively. In addition, 255 and 165 TSEGs were detected in the liver and jejunum of BG-fed group, while 162 and 211 TSEGs genes were observed in the liver and jejunum of BD-fed birds, respectively. Bioinformatic analysis with both IPA and DAVID-BR further revealed a significant enrichment of DEGs and TSEGs in the biological processes for reducing the synthesis, storage, transportation and secretion of lipids in the jejunum, while those in the liver were for enhancing the oxidation of ingested lipids and fatty acids. In particular, transcriptional regulators of THRSP and EGR-1 as well as several DEGs involved in the PPAR-α signaling pathway were significantly induced by dietary BG intervention for lipid catabolism. CONCLUSIONS: Our results demonstrate that BG reduces body fat deposition via regulation of gene expression, which is involved in the biological events relating to the reduction of synthesis, storage, transportation and secretion, and improvement of oxidation of lipids and fatty acids.

Inactivation and potential reactivation of pathogenic Escherichia coli O157:H7 in bovine milk exposed to three monochromatic ultraviolet UVC lights.

The ultraviolet (UVC) light irradiation has been recently studied as a novel non-thermal treatment method for milk. However, the potential reactivation of microorganisms following exposure to UVC light in milk medium was not studied yet. Therefore, the present study was conducted to determine the inactivation and reactivation of pathogenic Escherichia coli O157:H7 following exposure to UV light at three monochromatic wavelengths (222, 254 and 282 nm) in bovine milk. The results showed that inactivation of E. coli O157:H7 following exposure to the UV light at 254 nm was higher (P < 0.05) than that following exposure at 222 and 282 nm at the same UV fluence of 5, 10 and 20 mJ/cm(2). The reactivation of E. coli O157:H7 was increased as the incubation time and temperature increased regardless of the UV light sources under dark incubation phases. The evaluated reactivation ratios of E. coli O157:H7 following exposure to the UV light at 254 nm in milk were lower (P < 0.05) than that following exposure at 222 nm after 1 to 6, 2 to 5 and 5-6 h incubation at 4, 20 and 37 °C, respectively. Furthermore, at most incubation time points, the reactivation ratio of E. coli O157:H7 following exposure to these three UV light sources were lower (P < 0.05) than that of non-UV treated cells regardless of the incubation temperature. The lowest reactivation ratios of E. coli O157:H7 were observed after milk exposure to the UV light at 254 nm at 4 °C incubation when compared to that following exposure to the UV light at 222 and 282 nm.

Inactivation and potential reactivation of pathogenic Escherichia coli O157:H7 in apple juice following ultraviolet light exposure at three monochromatic wavelengths.

Ultraviolet (UV) light irradiation at 254 nm is considered as a novel non-thermal method for decontamination of foodborne pathogenic bacteria. However, lower penetration depth of UV light at 254 nm in apple juice resulted in higher UV dose consumption during apple juice decontamination. In addition, no studies are available on the reactivation of pathogens following exposure to UV light in drinks and beverages. Two novel monochromatic UV light sources (λ = 222 and 282 nm) have been developed for bacterial disinfection. However, the inactivation of pathogenic Escherichia coli O157:H7 following exposure to these UV wavelengths is still unclear. Therefore, the present study was conducted to determine the inactivation and reactivation potential of pathogenic E. coli O157:H7 in apple juice following exposure to UV light at three monochromatic wavelengths: Far UV (λ = 222 nm), Far UV+ (λ = 282 nm) and UVC light (λ = 254 nm). The results showed that E. coli O157:H7 is acid-resistant, and up to 99.50% of cells survived in apple juice when incubated at 20 °C for 24 h. Inactivation of E. coli O157:H7 following exposure to Far UV light (2.81 Log reduction) was higher (P < 0.05) than the inactivation caused by UVC light (1.95 Log reduction) and Far UV+ light (1.83 Log reduction) at the similar levels of UV fluence of 75 mJ/cm(2). No any reactivation potential was observed for E. coli O157:H7 in dark incubation phases after exposure to UV light as determined by the regular plating method. In addition, the exposure to Far UV light at 222 nm followed by incubating at 37 °C significantly decreased (P < 0.05) the survival of E. coli O157:H7 during dark incubation phase compared to that of UVC and Far UV+ light.

Reduction of Salmonella enterica serovar typhimurium DT104 infection in experimentally challenged weaned pigs fed a lactobacillus-fermented feed.

Salmonella Typhimurium is a foodborne pathogen and commonly present on pig farms. Probiotics have shown potential as a means of reducing Salmonella shedding in pigs. Three experimental challenge trials were conducted to investigate the potential application of newly isolated Lactobacillus isolates for controlling Salmonella infection in pigs. In each trial, 16 Yorkshire piglets (28-d old) were randomly allocated to 1 of 4 dietary treatments: (1) basal diet (BD), (2) naturally fermented (NF) feed, (3) Lactobacillus zeae-fermented (LZ-F) feed, and 4) Lactobacillus casei-fermented (LC-F) feed. All pigs consumed their assigned diets for 3 d prior to the challenge of Salmonella Typhimurium DT104 (approximately 6 log colony-forming units/pig) through gavage. Pediococcus pentosaceus, L. zeae, and L. casei were most abundant in NF, LZ-F, and LC-F feed, respectively. After the challenge, pigs on fermented feed had lower rectal temperature, diarrhea scores, serum haptoglobin concentrations, and intestinal Salmonella counts than the control group (BD) (p ≤ 0.01). Salmonella spp. were detected in both ileocecal lymph nodes (ICLN) and spleens from all pigs on BD, NF, and LC-F, but only 50% of spleens from pigs on LZ-F. Pigs had a dynamic spatial and temporal immune response to Salmonella infection and dietary treatments, as indicated by up- and downregulation in gene expression of inflammatory cytokines (interleukin (IL)-1ß, IL-6, IL-10, interferon-γ, and tumor necrosis factor) in the ileum, ICLN, and spleen. The alternation in cytokine expression by fermented feed, particularly LZ-F, appeared to benefit pigs in combating Salmonella infection.

Selected lactic acid-producing bacterial isolates with the capacity to reduce Salmonella translocation and virulence gene expression in chickens.

BACKGROUND: Probiotics have been used to control Salmonella colonization/infection in chickens. Yet the mechanisms of probiotic effects are not fully understood. This study has characterized our previously-selected lactic acid-producing bacterial (LAB) isolates for controlling Salmonella infection in chickens, particularly the mechanism underlying the control. METHODOLOGY/PRINCIPAL FINDINGS: In vitro studies were conducted to characterize 14 LAB isolates for their tolerance to low pH (2.0) and high bile salt (0.3-1.5%) and susceptibility to antibiotics. Three chicken infection trials were subsequently carried out to evaluate four of the isolates for reducing the burden of Salmonella enterica serovar Typhimurium in the broiler cecum. Chicks were gavaged with LAB cultures (10(6-7) CFU/chick) or phosphate-buffered saline (PBS) at 1 day of age followed by Salmonella challenge (10(4) CFU/chick) next day. Samples of cecal digesta, spleen, and liver were examined for Salmonella counts on days 1, 3, or 4 post-challenge. Salmonella in the cecum from Trial 3 was also assessed for the expression of ten virulence genes located in its pathogenicity island-1 (SPI-1). These genes play a role in Salmonella intestinal invasion. Tested LAB isolates (individuals or mixed cultures) were unable to lower Salmonella burden in the chicken cecum, but able to attenuate Salmonella infection in the spleen and liver. The LAB treatments also reduced almost all SPI-1 virulence gene expression (9 out of 10) in the chicken cecum, particularly at the low dose. In vitro treatment with the extracellular culture fluid from a LAB culture also down-regulated most SPI-1 virulence gene expression. CONCLUSIONS/SIGNIFICANCE: The possible correlation between attenuation of Salmonella infection in the chicken spleen and liver and reduction of Salmonella SPI-1 virulence gene expression in the chicken cecum by LAB isolates is a new observation. Suppression of Salmonella virulence gene expression in vivo can be one of the strategies for controlling Salmonella infection in chickens.

Digestion rate of dietary starch affects the systemic circulation of lipid profiles and lipid metabolism-related gene expression in weaned pigs.

The present study was conducted to investigate the effect of digestion rate of dietary starch on postprandial systemic circulating glucose, insulin and lipid profiles, and the activity and gene expression of lipid metabolism-related enzymes in weaned pigs. A total of twenty-four weaned pigs, surgically fitted with a catheter in the jugular vein, were randomly assigned to three dietary treatment groups, representing the high digestion rate starch (HDRS) group, the moderate-digestion rate starch (MDRS) group and the low-digestion rate starch (LDRS) group. The amylopectin:amylose ratios in the diets of each group were 27·6:1, 27·6:8·5 and 1:27·6, respectively. The serum concentrations of glucose, TAG, total cholesterol, LDL-cholesterol and HDL-cholesterol in the HDRS group were increased to the peak point at postprandial 1·5, 2·5, 2·5, 1·5 and 1·5 h, those in the MDRS group were at postprandial 2·5, 3·5, 3·5, 3·5 and 3·5 h and those in the LDRS group were at postprandial 2·5, 3·5, 3·5, 1·5 and 3·5 h, respectively. The serum concentration of insulin in the HDRS group was higher (P < 0·05) than those in the MDRS group, and those in the MDRS group was also higher (P < 0·05) than those in the LDRS group at postprandial 0·5, 1·5 and 2·5 h, respectively. The serum concentrations of acetate, propionate and butyrate in the HDRS group were higher (P < 0·05) than those in the MDRS group, and those in the MDRS group were higher (P < 0·05) than in the LDRS group in each feeding cycle, in turn, respectively. The activity of fatty acid synthase (FAS) in the liver and abdominal adipose tissues, that of acetyl CoA carboxylase (ACC) in the myocardium and interscapular brown adipose tissues and that of the ATP-citrate lyase (ATP-CL) in the liver and interscapular brown adipose tissues in pigs of the HDRS group were higher (P < 0·05) than that of the MDRS group. The mRNA levels of FAS in the myocardium, liver and interscapular brown adipose tissues of pigs in the HDRS group were higher (P < 0·05) than those of the MDRS group. The activities and mRNA levels of FAS, ACC and ATP-CL in the myocardium, liver, abdominal and interscapular brown adipose tissues of the HDRS group were higher than those of the LDRS group. We conclude that the digestion rate of dietary starch affected not only the postprandial systemic circulating levels of glucose and insulin but also the lipid metabolism in weaned pigs. Dietary starch with higher digestion rate produces higher blood glucose and insulin response, ameliorates the blood lipid profiles and up-regulates the activity and gene expression profile of lipid metabolism-related genes in weaned pigs.

Digestion rate of dietary starch affects systemic circulation of amino acids in weaned pigs.

The present study was conducted to evaluate the in vitro and in vivo digestibility of dietary starch and its digestive behaviour on the systemic circulating amino acids (AA) in weaned pigs. Eighteen weanling pigs surgically fitted with a catheter in the jugular vein were randomly assigned to three dietary treatment groups. Sticky rice starch (SRS) was hydrolysed more quickly in vitro (P < 0.05) than maize starch (MS) and resistant starch (RS), and was almost completely hydrolysed within 4 h. The in vivo digestibility of dietary starch in different segments of the small intestine was significantly different. SRS was digested (81.9 %; P < 0.05) in the anterior jejunum, but not more than half of the MS and RS was digested in the same segment of the small intestine. The digestibilities of isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, valine, alanine, aspartate and serine in the SRS group were higher than in the MS group (P < 0.05), and all nutritionally indispensable and dispensable AA in the SRS group were higher when compared with those in the RS group (P < 0.05). The serum concentrations of nutritionally indispensable AA, proline and serine in the three groups were increased to a peak point within 1.5 h postprandially then decreased gradually; however, the time that serum concentrations of alanine, aspartate, glutamate and glycine in each group increased to a peak point was different. The concentrations of nutritionally indispensable AA, including arginine, cystine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 09.30 hours and arginine, cystine, histidine, isoleucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 13.30 hours in the SRS group were higher than in the MS group (P < 0.05); all nutritionally indispensable AA in the SRS group were higher than in the RS group at 09.30 and 13.30 hours (P < 0.05), respectively. We conclude that dietary starches digested rapidly in vitro have higher digestibility in the anterior small intestine of pigs. Diets containing rapidly digestible starch ameliorate the digestive and absorptive function and regulate AA metabolism to beneficially increase the entry of dietary AA into the systemic circulation in pigs.