Nuria Canibe

Influence of dietary zinc oxide and copper sulfate on the gastrointestinal ecosystem in newly weaned piglets

ABSTRACT Dietary doses of 2,500 ppm ZnO-Zn reduced bacterial activity (ATP accumulation) in digesta from the gastrointestinal tracts of newly weaned piglets compared to that in animals receiving 100 ppm ZnO-Zn. The amounts of lactic acid bacteria (MRS counts) and lactobacilli (Rogosa counts) were reduced, whereas coliforms (MacConkey counts) and enterococci (Slanetz counts, red colonies) were more numerous in animals receiving the high ZnO dose. Based on 16S rRNA gene sequencing, the colonies on MRS were dominated by three phylotypes, tentatively identified as Lactobacillus amylovorus (OTU171), Lactobacillus reuteri (OTU173), and Streptococcus alactolyticus (OTU180). The colonies on Rogosa plates were dominated by the two Lactobacillus phylotypes only. Terminal restriction fragment length polymorphism analysis supported the observations of three phylotypes of lactic acid bacteria dominating in piglets receiving the low ZnO dose and of coliforms and enterococci dominating in piglets receiving the high ZnO dose. Dietary doses of 175 ppm CuSO4-Cu also reduced MRS and Rogosa counts of stomach contents, but for these animals, the numbers of coliforms were reduced in the cecum and the colon. The influence of ZnO on the gastrointestinal microbiota resembles the working mechanism suggested for some growth-promoting antibiotics, namely, the suppression of gram-positive commensals rather than potentially pathogenic gram-negative organisms. Reduced fermentation of digestible nutrients in the proximal part of the gastrointestinal tract may render more energy available for the host animal and contribute to the growth-promoting effect of high dietary ZnO doses. Dietary CuSO4 inhibited the coliforms and thus potential pathogens as well, but overall the observed effect of CuSO4 was limited compared to that of ZnO.

Methylotrophic methanogenic Thermoplasmata implicated in reduced methane emissions from bovine rumen

Rumen methanogens are major sources of anthropogenic methane emissions, and these archaea are targets in strategies aimed at reducing methane emissions. Here we show that the poorly characterised Thermoplasmata archaea in bovine rumen are methylotrophic methanogens and that they are reduced upon dietary supplementation with rapeseed oil in lactating cows. In a metatranscriptomic survey, Thermoplasmata 16S rRNA and methyl-coenzyme M reductase (mcr) transcripts decreased concomitantly with mRNAs of enzymes involved in methanogenesis from methylamines that were among the most abundant archaeal transcripts, indicating that these Thermoplasmata degrade methylamines. Their methylotrophic methanogenic lifestyle was corroborated by in vitro incubations, showing enhanced growth of these organisms upon methylamine supplementation paralleled by elevated methane production. The Thermoplasmata have a high potential as target in future strategies to mitigate methane emissions from ruminant livestock. Our findings and the findings of others also indicate a wider distribution of methanogens than previously anticipated.

New insight into butyrate metabolism.

Butyrate is a C4 acid produced by microbial fermentation of carbohydrates and protein in the large intestine of all animal species. The factor of prime importance for the production rate of butyrate in the lower gut is type and levels of non-digestible carbohydrates entering the large intestine. It was previously believed that 85-90 % of the butyrate produced in the gut was cleared when passing the gut epithelium, but recent studies with catheterised pigs have shown that the concentration of butyrate in the portal vein is strongly influenced by the production rate in the large intestine. Increased gut production of butyrate further raises the circulating level of butyrate. For good reason it is not possible with current technologies to perform direct measurements of the variation in the butyrate concentration in the portal vein of human subjects, but short-chain fatty acid levels in portal blood from sudden-death victims, subjects undergoing emergency surgery or planned surgery have indicated a higher gut production and absolute and relative concentration of butyrate in non-fasted as compared with fasted human subjects. However, despite an expected higher gut production of butyrate when feeding a high-fibre rye-bread-based diet as compared with a low-fibre wheat-bread-based diet, there was no difference in absolute or relative levels of butyrate in the peripheral blood of human subjects.

Breakdown of plant carbohydrates in the digestive tract of pigs fed on wheat- or oat-based rolls

Cell wall materials from various cellular tissues of cereals may potentially influence the digestion and absorption processes in different ways. The objective of the present investigation was to study the breakdown of plant carbohydrates in the gastrointestinal tract of pigs fed a low-fibre (LF; 65 g kg−1 dry matter) wheat flour-based diet and two high-fibre diets with added insoluble fibre from wheat bran (HFWB; 112 g kg−1 dry matter) or soluble fibre from oat bran (HFOB; 108 g kg−1 dry matter). The diets were formulated to provide ∼0.31 energy from fat, ∼0.18 energy from protein and ∼0.51 energy from carbohydrates and were offered as baked rolls to eight ileum-cannulated hypercholesterolemic pigs in a crossover design. Carbohydrates were the predominant ileal constituent, with most of the carbohydrates present as non-starch polysaccharides (NSP). Starch in all diets was almost completely digested at this site of the gastrointestinal tract, with digestibility values above 0.99. The ingested amount of NSP was quantitatively recovered in ileal materials with the wheat-based diets, while there was a significant loss of 0.27 of NSP primarily as mixed linked (13)(14)--D-glucan with diet HFOB. The concentration and flow of lactic acid were also highest in the ileum after feeding diet HFOB, indicating that -glucan stimulated lactic acid formation. Any soluble components that reached the large intestine were almost completely broken down, while the digestibility of insoluble NSP constituents was significantly lower for diets LF and HFWB than for diet HFOB. The high degradation of oat bran resulted in a lower effect on faecal dry and wet bulking than was found with wheat bran. In conclusion, cereal starch was practically completely degraded in the small intestine, while the site and extent of NSP degradation, lactic acid formation and bulking properties were influenced by the fibre source. © 2000 Society of Chemical Industry

Potential Rates of Fermentation in Digesta from the Gastrointestinal Tract of Pigs: Effect of Feeding Fermented Liquid Feed

ABSTRACT Microbial catabolic capacity in digesta from the gastrointestinal tract of pigs fed either dry feed or fermented liquid feed (FLF) was determined with the PhenePlate multisubstrate system. The in vitro technique was modified to analyze the kinetics of substrate catabolism mediated by the standing stock of enzymes (potential rates of fermentation), allowing a quantitative evaluation of the dietary effect on the catabolic capacity of the microbiota. In total, the potential rates of fermentation were significantly reduced in digesta from the large intestine (cecum, P < 0.1; colon, P < 0.01; and rectum, P < 0.0001) of pigs fed FLF compared to pigs fed dry feed. No effect of diet was observed in the stomach (P = 0.71) or the distal part of the small intestine (P = 0.97). The highest rates of fermentation and the most significant effect of diet were observed for readily fermentable carbohydrates like maltose, sucrose, and lactose. Feeding FLF to pigs also led to a reduction in the large intestine of the total counts of anaerobic bacteria in general and lactic acid bacteria specifically, as well as of microbial activity, as determined by the concentration of ATP and short-chain fatty acids. The low-molecular-weight carbohydrates were fermented mainly to lactic acid in the FLF before being fed to the animals. This may have limited microbial nutrient availability in the digesta reaching the large intestine of pigs fed FLF and may have caused the observed reduction in activity and density of the cecal and colonic microbial population. On the other hand, feeding FLF to pigs reduced the viable counts of coliform bacteria (indicator of Escherichia coli and Salmonella spp.) most profoundly in the stomach and the distal part of the small intestine, probably due to the bactericidal effect of lactic acid and low pH. The results presented clearly demonstrate that feeding FLF to pigs had a great impact on the indigenous microbiota, as reflected in bacterial numbers, short-chain fatty acid concentration, and substrate utilization. However, completely different mechanisms may be involved in the proximal and the distal parts of the gastrointestinal tract. The present study illustrates the utility of the PhenePlate system for quantifying the catabolic capacity of the indigenous gastrointestinal tract microbiota.

Quantification of the absorption of nutrients derived from carbohydrate assimilation: model experiment with catheterised pigs fed on wheat- or oat-based rolls

The main purpose of this study was to quantify the absorption of nutrients derived from carbohydrate assimilation in a model experiment with catheterised pigs. A low-fibre (LF) diet based on wheat flour and two high-fibre diets with added insoluble fibre from wheat bran (HFWB) or soluble fibre from oat bran (HFOB) were used. The diets were offered as baked rolls to three catheterised pigs in a 3 x 3 Latin square design. The pigs were surgically fitted with catheters placed in the portal vein and mesenteric artery and with an ultrasonic flow probe attached to the portal vein to monitor the blood-flow rate. The pigs were fed the diets three times daily and portal and arterial blood samples collected twice weekly up to 8 h after the morning feeding. Glucose, insulin, lactic acid (LA) and short-chain fatty acids (SCFA) were determined on the samples. The baseline level of glucose in the portal vein was about 6 mmol/l increasing to 10-11 mmol/l 20-30 min post-feeding with no difference among the different diets. Portal and arterial insulin mirrored portal glucose concentration and was also unaffected by the dietary composition. The net absorption of glucose (per 24 h) was: diet LF 4190 mmol; diet HFWB 3050 mmol and diet HFOB 3190 mmol corresponding to a recovery of 0.76-0.92 of ingested starch. The levels of LA and SCFA in the portal vein were relatively constant in the postprandial period. The net absorption of LA and SCFA was in the same order (749 and 720 mmol/d respectively) with diet LF, while LA was lower (384 and 582 mmol/d) and SCFA higher (738 to 891 mmol/d) when feeding the two high-fibre diets. There was a higher molar proportion of butyrate in the portal vein after feeding the high-fibre diet supplemented with oat bran as compared with the wheat-based diets.

Digestibility of dried and toasted peas in pigs. 1. Ileal and total tract digestibilities of carbohydrates

Abstract The ileal and total tract digestibilities of carbohydrates were studied in pigs given diets containing dried or toasted peas ( Pisum sativum var. Solara) as the sole source of polysaccharides. Peas from two different harvest years were fed to growing pigs fitted with a cannula at the end of the ileum in two experiments. Two types of cannulas were used in the experiments, a T-shaped cannula designed to collect total digesta and a simple T-shaped cannula. Toasting decreased the ileal digestibility of α-galactosides from 98.7 to 96.4% in one harvest of peas and from 65.8 to 41.5% in the other harvest. In vitro studies showed that hydrolysis of pea starch is a relatively slow process. Toasting did not result in gelatinization of starch. However, heat applied in the present conditions did not affect starch digestibility in one of the harvests, whereas a decreased effect was observed in the other. Pea non-starch polysaccharides (NSP) were partially degraded by the distal ileum and had largely disappeared by faecal level, with digestibility values of total NSP between 86.2 and 90.9%. Arabinose and uronic acids were highly digested, whereas glucose and xylose showed lower values. Toasting affected NSP digestibility but its importance was difficult to assess. Moreover, different tendencies were observed in the two harvests of peas: one showing a tendency for increased digestibilities after toasting and the other showing the reverse. It was concluded that different growing conditions or small differences during processing may have affected the digestibility of carbohydrates observed for the dried and toasted peas studied.

Chemical composition, digestibility and protein quality of 12 sunflower (Helianthus annuus L) cultivars

Twelve sunflower (Helianthus annuus L) cultivars grown in Spain were analysed and tested in experiments with rats. The dehulled seeds contained an average of 32.2 MJ kg−1 dry matter (DM) gross energy, 653 g kg−1 DM fat, 60 g kg−1 DM total non-starch polysaccharides (NSP) and 6 g kg−1 DM Klason lignin. The sunflower seed hulls contained 20.2 MJ kg−1 DM gross energy, 53 g kg−1 DM fat, 562 g kg−1 DM total NSPs and 239 g kg−1 DM Klason lignin. The sunflower samples were dehulled and partially defatted (to ∼17% fat) and included in diets for rats. The dehulled, partially defatted samples contained on average 74.6 g nitrogen kg−1 DM and 1.409 mg g−1 phenolic compounds (chlorogenic acid + caffeic acid + derivative 1 + derivative 2) varying from 0.677 to 2.847 mg g−1. Groups of five growing rats were fed diets (9.38% crude protein) containing one of the sunflower cultivars as the only source of protein. Apparent ileal and faecal digestibilities were determined by using an indigestible marker (Cr2O3) and faecal digestibility based on total faecal collections. Apparent ileal, caecal and faecal digestibilities of organic matter were 81.2–91.5% (P = 0.05), 95.8–97.1% (P = 0.005) and 94.7–95.3% (P = 0.94) respectively. The apparent faecal digestibilities of DM, energy and protein (N × 6.25) were 93.2–93.8%, 93.5–94.3% and 81.6–84.3% respectively with no differences among cultivars. Biological value (BV) ranged between 63.8 and 73.2% (P = 0.0001) and net protein utilisation (NPU) between 59.9 and 69.5% (P = 0.0001). BV and NPU were positively correlated with lysine and threonine contents, but no correlation with the analysed phenolic compounds was detected. © 1999 Society of Chemical Industry

Digestibility of dried and toasted peas in pigs. 2. Ileal and total tract digestibilities of amino acids, protein and other nutrients

Two experiments in which pigs were fed dried or toasted peas (Pisum sativum var. Solara) from 2 years of harvest were performed. Diets with peas as the sole source of nitrogen were formulated to contain ≈ 170 g kg−1 crude protein (CP). Toasting applied in the present conditions (moisture content ≈ 150 g kg−1, 130°C, 3–4 min) did not damage the lysine of the peas. The animals were fitted with a T-shaped cannula at the end of the ileum, and two balances with ileal and faecal collections were carried out. When peas from one of the harvests (Experiment 1) were fed, the ileal digestibility of most amino acids was increased by toasting; the digestibility of dry matter (DM) increased from 69.4 to 76.1%, the digestibility of energy from 71.2 to 77.2%, and the same tendency (P = 0.16) was observed for protein digestibility. When peas from the other harvest (Experiment 2) were fed, no effect of toasting was observed on the ileal digestibilities of nutrients. DM (P = 0.16) and energy (P = 0.12) digestibilities showed tendencies for lower values after toasting. At total tract level, digestibilities were higher than at ileal level, and no effect of heat treatment on the digestibilities of nutrients was observed in either of the two experiments. It was concluded that toasting applied under specified conditions (moisture content ≈ 150 g kg−1, 130°C, 3–4 min) can improve the ileal digestibility of peas. However, harvests of different years can show different digestibilities and heat treatment can affect them unequally. Therefore, conclusions should be drawn with caution.

The effect of Artemisia annua on broiler performance, on intestinal microbiota and on the course of a Clostridium perfringens infection applying a necrotic enteritis disease model

The aerial parts of the plant Artemisia annua contain essential oils having antimicrobial properties against Clostridium perfringens Type A, the causal agent for necrotic enteritis in broilers. In two experiments, the influence of increasing dietary concentrations of dried A. annua leaves (0, 5, 10 and 20 g/kg) and n-hexane extract from fresh A. annua leaves (0, 125, 250 and 500 mg/kg) on broiler performance was investigated. Dried plant material decreased feed intake and body weight in a dose-dependent manner, and 10 and 20 g/kg diet tended to improve the feed conversion ratio. The n-hexane extract also reduced feed intake, but broiler weight tended to decrease only at the highest dietary concentration. The feed conversion ratio tended to improve when birds received 250 and 500 mg/kg n-hexane extract. In a third experiment, a necrotic enteritis disease model was applied to investigate the effect of the dietary addition of dried A. annua leaves (10 g/kg on top) or n-hexane extract of A. annua (250 mg/kg) on the severity of the disease in broilers. The addition of n-hexane extract reduced the intestinal C. perfringens numbers and the severity of the disease-related small intestinal lesions. Over the infection period from day 17 to day 27, birds supplemented with the n-hexane extract gained more weight than both the challenged control birds and birds receiving dried plant material. The results indicate that n-hexane extracts derived from A. annua can modulate the course of necrotic enteritis and compensate to a certain extent for the disease-associated weight losses.