Composition of mucus- and digesta-associated bacteria in growing pigs with and without diarrhea differed according to the presence of colonic inflammation.

BACKGROUND: In the pig production, diarrhea can occur during different growth stages including the period 4-16 weeks post weaning, during which a diarrheal outbreak also termed as colitis-complex diarrhea (CCD) can occur and it is distinct from post-weaning diarrhea (1-2 weeks post weaning). We hypothesized that CCD in growing pigs is associated with changes in colonic microbiota composition and fermentation patterns, and the aim of the present observational study was to identify changes in digesta-associated bacteria (DAB) and mucus-associated bacteria (MAB) in the colon of growing pigs with and without diarrhea. A total number of 30 pigs (8, 11, and 12 weeks of age) were selected; 20 showed clinical signs of diarrhea and 10 appeared healthy. Based on histopathological examination of colonic tissues, 21 pigs were selected for further studies and classified as follows: without diarrhea, no colon inflammation (NoDiar; n = 5), with diarrhea, without colonic inflammation (DiarNoInfl; n = 4), and with diarrhea, with colonic inflammation (DiarInfl; n = 12). Composition (based on 16S rRNA gene amplicon sequencing) and fermentation pattern (short-chain fatty acids; SCFA profile) of the DAB and MAB communities were characterized. RESULTS: The DAB showed higher alpha diversity compared to MAB in all pigs, and both DAB and MAB showed lowest alpha diversity in the DiarNoInfl group. Beta diversity was significantly different between DAB and MAB as well as between diarrheal groups in both DAB and MAB. Compared to NoDiar, DiarInfl showed increased abundance of various taxa, incl. certain pathogens, in both digesta and mucus, as well as decreased digesta butyrate concentration. However, DiarNoInfl showed reduced abundance of different genera (mainly Firmicutes) compared to NoDiar, but still lower butyrate concentration. CONCLUSION: Diversity and composition of MAB and DAB changed in diarrheal groups depending on presence/absence of colonic inflammation. We also suggest that DiarNoInfl group was at the earlier stage of diarrhea compared with DiarInfl, with a link to dysbiosis of colonic bacterial composition as well as reduced butyrate concentration, which plays a pivotal role in gut health. This could have led to diarrhea with inflammation due to a dysbiosis, associated with an increase in e.g., Escherichia-Shigella (Proteobacteria), Helicobacter (Campylobacterota), and Bifidobacterium (Actinobacteriota), which may tolerate or utilize oxygen and cause epithelial hypoxia and inflammation. The increased consumption of oxygen in epithelial mucosal layer by infiltrated neutrophils may also have added up to this hypoxia. Overall, the results confirmed that changes in DAB and MAB were associated with CCD and reduced butyrate concentration in digesta. Moreover, DAB might suffice for future community-based studies of CCD.

Effect of toasting and decortication of oat on rumen biohydrogenation and intestinal digestibility of fatty acids in dairy cows.

This experiment quantified the effect of decorticated and toasted oat (Avena sativa L.) on fatty acid (FA) supply, ruminal biohydrogenation (BH) of FA, and intestinal digestibility of FA in 4 ruminal and intestinal cannulated Danish Holstein cows. Experimental diets containing untreated oat, decorticated oat, toasted oat, and decorticated and toasted oat were fed ad libitum to the cows in a 2 × 2 factorial arrangement in a Latin square design throughout 4 periods. Unless otherwise mentioned, the results of this study indicate the main effect of decortication and toasting. Decortication increased the intake of FA by 40.3 g/d and increased feed-ileum digested FA, whereas toasting decreased the intake of FA by 69.3 g/d. Toasting increased both feed-ileum and total-tract digestibility of FA by 59.8 and 67.4 g/kg of FA intake, respectively. The proportion of C18:2n-6 in FA intake increased, and the C18:3n-3 proportion in FA intake decreased due to decortication. Toasting resulted in a dramatic reduction of the C18:2n-6 proportion in FA intake, and it increased the proportions of C18:0 and C18:3n-3 in FA intake. Toasting reduced ruminal BH of C18:1n-9 and C18:2n-6 by 134 and 11.7 g/kg of FA intake, respectively, and toasting increased the proportion of unsaturated FA to saturated FA in the duodenal FA flow. Decortication decreased the ruminal BH of C18:3n-3 by 38.0 g/kg of FA intake. Decortication increased small intestinal digestibility of C12:0, C15:0, C20:0, and C22:0. Toasting increased the small intestinal digestibility of C15:0, C18:0, trans-C18:1, C20:0, and C24:0. Toasting reduced the small intestinal digestibility of C18:1n-9, C18:2n-6, and C20:1n-9. This study showed that decortication successfully increased the intake of FA and flow of FA at the duodenum and feed-ileum digested FA. However, toasting oat at 121°C caused a remarkable decline in FA concentration in oat, and thereby FA intake; therefore, toasting cannot be recommended.

Effects of toasting and decortication of oat on nutrient digestibility in the rumen and small intestine and on amino acid supply in dairy cows.

This study examined the potential for decorticating and toasting of oat (Avena sativa) to supply crude protein (CP) and amino acids (AA) in dairy cows. Four lactating Danish Holstein Friesian cows fitted with ruminal, duodenal, and ileal cannulas were assigned to a 4 × 4 Latin square design. Cows were fed experimental diets ad libitum based on grass-clover silage and toasted fava beans, with oat included in different forms arranged in a 2 × 2 factorial: whole oat, decorticated oat, toasted oat, and decorticated toasted oat. In situ rumen degradability of processed oat was also evaluated. Decortication increased starch intake by 0.38 kg/d and reduced NDF intake by 0.91 kg/d. Toasting reduced ruminal AA digestibility and increased duodenal flow of CP by 0.41 kg/d. In situ degradation rate and effective degradability of CP in the rumen were reduced by 0.46 h-1 and 310 g/kg CP due to toasting. Both decortication and toasting increased microbial synthesis of CP by 0.20 and 0.41 kg/d, respectively. Decortication and toasting did not affect small intestinal AA digestibility, but did increase the total digested amount of AA by 154 and 250 g/d, respectively. Milk production was not affected by treatments. Methane production (L/d) decreased with decortication and toasting. In conclusion, unless an interaction exists between decortication and toasting, the results indicate additive effects of toasting and decorticating oat for increasing the supply of digestible AA to the small intestine of dairy cows.

Effect of oat decortication on chemical composition, in vitro digestibility and in situ degradability.

The effect of decortication on chemical composition and degradability characteristics of four Danish oat varieties was investigated. Effective degradability (ED) and post-ruminal disappearance (PRD) were measured by in situ and mobile bag techniques respectively. Decorticated oat showed higher (p = .01) concentrations of crude protein (CP; 134 vs. 108 g/kg DM) and crude fat (71.6 vs. 53.1 g/kg DM) and a higher (p = .001) organic matter digestibility (OMD; 888 vs. 703 g/kg OM) than oat. The content of total fatty acids (FA) in DM was higher in decorticated oat. The proportion of linoleic acid (C18:2 n6) increased (p < .05) due to decortication, while the linolenic acid (C18:3 n3) proportion of total FA decreased in decorticated oat. Decortication increased (p = .01) the concentration of amino acids (AA), but the proportion of lysine in total AA decreased (p < .002). Effective degradability (ED) of both DM and CP was (p < .001) higher in decorticated oat. Decortication increased the total tract disappearance (TTD) and PRD of CP (p < .001). In conclusion, decortication can be used as a practical approach to increase the nutritional value of oat.

Draft genome sequences of 53 Lactococcus and Leuconostoc strains isolated from two undefined DL-starter cultures.

This study presents the complete genomes of 53 strains of Lactococcus and Leuconostoc isolated from two undefined DL-starter cultures originating from Denmark, Tistrup, and P. The genomes were reconstructed using long-read, nanopore-based DNA sequencing, delivering comprehensive data set for comparative genomics and taxonomic classification, with potential utility in dairy fermentation processes.

Formation of RRR-α-tocopherol in rumen and intestinal digestibility of tocopherols in dairy cows.

Tocopherol sources in diets are often a combination of all-rac-α-tocopheryl acetate (synthetic α-tocopherol) from vitamin supplements and natural tocopherols and 2R-(4'R, 8'R)-5,7,8-trimethyltocotrienol (α-tocotrienols) from the feed sources. Synthetic α-tocopherol consists of 8 different stereoisomers including 2R-(4'R, 8'R)-5,7,8-trimethyltocol (RRR-α-tocopherol), 2R-(4'S, 8'R)-5,7,8-trimethyltocol (RSR-α-tocopherol), 2R-(4'R, 8'S)-5,7,8-trimethyltocol (RRS-α-tocopherol), 2R-(4'S, 8'S)-5,7,8-trimethyltocol (RSS-α-tocopherol), 2S-(4'S, 8'S)-5,7,8-trimethyltocol (SSS-α-tocopherol), 2S-(4'R, 8'S)-5,7,8-trimethyltocol (SRS-α-tocopherol), 2S-(4'S, 8'R)-5,7,8-trimethyltocol (SSR-α-tocopherol), and 2S-(4'R, 8'R)-5,7,8-trimethyltocol (SRR-α-tocopherol). The pre-absorption metabolism of tocopherols and tocotrienols in ruminants differs from monogastric animals due to the extensive microbial fermentation in the anaerobic rumen. The current study investigated the impact of toasting and decortication of oats on metabolism in the digestive tract (synthesis, digestion), and intestinal digestibility of tocopherols in dairy cows by using 4 ruminal and intestinal cannulated Danish Holstein cows in a 4 × 4 Latin square design for 4 periods. Cows were fed a total mixed ration ad libitum containing different forms of oats: whole oat, decorticated oat, toasted oat, and decorticated toasted oat, all rolled before mixed ration. Overall means across 4 treatments were statistically analyzed, testing whether overall means were different from zero. Decortication or toasting did not affect the balance or digestibility of α-tocopherols in rumen. Average across treatments showed the ruminal degradation of synthetic α-tocopherol (279 mg/d, P = 0.02; P-value shows that average across treatments is different from zero), synthetic 2R-α-tocopherol (133 mg/d, P < 0.01; summation of RRS-, RSR- and RSS-α-tocopherol), and 2S-α-tocopherol (190 mg/d; P < 0.01, summation of SSS-, SRS-, SSR, and SRR-α-tocopherol), while RRR-α-tocopherol was formed in the rumen (221 mg/d, P = 0.10). The average across treatments showed that small intestinal digestibility of tocopherols ranked in the following order: α-tocotrienol > natural α-tocopherol > synthetic α-tocopherols > 2R-(4'R, 8'R)-,7,8-dimethyltocol (γ-tocopherol). The average across treatments for small intestinal and feed-ileum digestibility ranked in the following order: RRR-α-tocopherol > synthetic 2R-α-tocopherol > 2S-α-tocopherol. Results showed the first evidence for RRR-α-tocopherol formation under anaerobic conditions in the rumen. In addition, synthetic α-tocopherol stereoisomers, γ-tocopherol and α-tocotrienol were degraded in the rumen. There was a discrimination against absorption of synthetic 2R- and 2S-α-tocopherol in the small intestine.

A westernized diet changed the colonic bacterial composition and metabolite concentration in a dextran sulfate sodium pig model for ulcerative colitis.

Introduction: Ulcerative colitis (UC) is characterized by chronic inflammation in the colonic epithelium and has a blurred etiology. A western diet and microbial dysbiosis in the colon were reported to play a role in UC development. In this study, we investigated the effect of a westernized diet, i.e., increasing fat and protein content by including ground beef, on the colonic bacterial composition in a dextran sulfate sodium (DexSS) challenged pig study. Methods: The experiment was carried out in three complete blocks following a 2×2 factorial design including 24 six-week old pigs, fed either a standard diet (CT) or the standard diet substituted with 15% ground beef to simulate a typical westernized diet (WD). Colitis was induced in half of the pigs on each dietary treatment by oral administration of DexSS (DSS and WD+DSS, respectively). Samples from proximal and distal colon and feces were collected. Results and discussion: Bacterial alpha diversity was unaffected by experimental block, and sample type. In proximal colon, WD group had similar alpha diversity to CT group and the WD+DSS group showed the lowest alpha diversity compared to the other treatment groups. There was a significant interaction between western diet and DexSS for beta diversity, based on Bray-Curtis dissimilarly. The westernized diet and DexSS resulted in three and seven differentially abundant phyla, 21 and 65 species, respectively, mainly associated with the Firmicutes and Bacteroidota phyla followed by Spirochaetota, Desulfobacterota, and Proteobacteria. The concentration of short-chain fatty acids (SCFA) was lowest in the distal colon. Treatment had a slight effect on the estimates for microbial metabolites that might have valuable biological relevance for future studies. The concentration of putrescine in the colon and feces and that of total biogenic amines was highest in the WD+DSS group. We conclude that a westernized diet could be a potential risk factor and an exacerbating agent for UC by reducing the abundance of SCFA-producing bacteria, increasing the abundance of pathogens such as Helicobacter trogontum, and by increasing the concentration of microbial proteolytic-derived metabolites in the colon.

Corrigendum: A westernized diet changed the colonic bacterial composition and metabolite concentration in a dextran sulfate sodium pig model for ulcerative colitis.

[This corrects the article DOI: 10.3389/fmicb.2023.1018242.].

Etiology of Colitis-Complex Diarrhea in Growing Pigs: A Review.

Colitis-complex diarrhea (CCD) in pigs can be defined as a type of diarrhea, which is associated with colonic inflammation and disrupted colonic gut barrier functionality in growing pigs (4-16 weeks post-weaning). It is a challenge for the pig industry as it is associated with the high use of antibiotics, reduced animal welfare, and depressed growth rate. The exact etiology of CCD is still unclear; however, pathogens including Brachyspira (B.) hyodysenteriae, B. pilosicoli, and swine whipworms such as Trichuris (T.) suis have been involved in specific colitis (SC). In the absence of specific pathogens, dietary factors, such as high levels of protein, pelleted feedstuffs, and lack of sufficient antioxidants, can result in non-specific colitis (NSC). On the other hand, supplement of polyunsaturated fatty acids (PUFA) and polyphenols, sufficient supply of essential amino acids (e.g., threonine, cysteine, and proline), short-chain fatty acids (SCFA; especially butyrate), and resistant starch have shown to confer preventing/ameliorating effects on CCD. Different putative biomarkers associated with CCD have been presented. It is anticipated that a comprehensive picture of the possible causes of CCD and potential dietary interventions could cast light on the direction of future studies aimed at developing preventive and curative strategies against CCD in growing pigs.