Effects of epinephrine, norepinephrine, and phenylephrine on microcirculatory blood flow in the gastrointestinal tract in sepsis

OBJECTIVE: The use of vasopressors for treatment of hypotension in sepsis may have adverse effects on microcirculatory blood flow in the gastrointestinal tract. The aim of this study was to measure the effects of three vasopressors, commonly used in clinical practice, on microcirculatory blood flow in multiple abdominal organs in sepsis. DESIGN: Random order, cross-over design. SETTING: University laboratory. SUBJECTS: Eight sedated and mechanically ventilated pigs. INTERVENTIONS: Pigs were exposed to fecal peritonitis-induced septic shock. Mesenteric artery flow was measured using ultrasound transit time flowmetry. Microcirculatory flow was measured in gastric, jejunal, and colon mucosa; jejunal muscularis; and pancreas, liver, and kidney using multiple-channel laser Doppler flowmetry. Each animal received a continuous intravenous infusion of epinephrine, norepinephrine, and phenylephrine in a dose increasing mean arterial pressure by 20%. The animals were allowed to recover for 60 mins after each drug before the next was started. MEASUREMENTS AND MAIN RESULTS: During infusion of epinephrine (0.8 +/- 0.2 mug/kg/hr), mean arterial pressure increased from 66 +/- 5 to 83 +/- 5 mm Hg and cardiac index increased by 43 +/- 9%. Norepinephrine (0.7 +/- 0.3 mug/kg/hr) increased mean arterial pressure from 70 +/- 4 to 87 +/- 5 mm Hg and cardiac index by 41 +/- 8%. Both agents caused a significant reduction in superior mesenteric artery flow (11 +/- 4%, p < .05, and 26 +/- 6%, p < .01, respectively) and in microcirculatory blood flow in the jejunal mucosa (21 +/- 5%, p < .01, and 23 +/- 3%, p < .01, respectively) and in the pancreas (16 +/- 3%, p < .05, and 8 +/- 3%, not significant, respectively). Infusion of phenylephrine (3.1 +/- 1.0 mug/kg/min) increased mean arterial pressure from 69 +/- 5 to 85 +/- 6 mm Hg but had no effects on systemic, regional, or microcirculatory flow except for a 30% increase in jejunal muscularis flow (p < .01). CONCLUSIONS: Administration of the vasopressors phenylephrine, epinephrine, and norepinephrine failed to increase microcirculatory blood flow in most abdominal organs despite increased perfusion pressure and-in the case of epinephrine and norepinephrine-increased systemic blood flow. In fact, norepinephrine and epinephrine appeared to divert blood flow away from the mesenteric circulation and decrease microcirculatory blood flow in the jejunal mucosa and pancreas. Phenylephrine, on the other hand, appeared to increase blood pressure without affecting quantitative blood flow or distribution of blood flow.

Nuclear receptor and nuclear receptor target gene messenger ribonucleic acid levels at different sites of the gastrointestinal tract and in liver of healthy dogs

Nuclear receptors (NR) are ligand-activated transcription factors that regulate different metabolic pathways by influencing the expression of target genes. The current study examined mRNA abundance of NR and NR target genes at different sites of the gastrointestinal tract (GIT) and the liver of healthy dogs (Beagles; n = 11). Samples of GIT and liver were collected postmortem and homogenized, total RNA was extracted and reverse transcribed, and gene expression was quantified by real-time reverse-transcription PCR relative to the mean of 3 housekeeping genes (beta-actin, glyceraldehyde-3-phosphate dehydrogenase, and ubi-quitin). Differences were observed (P < or = 0.05) in the mRNA abundance among stomach (St), duodenum (Du), jejunum (Je), ileum (Il), and colon (Col) for NR [pregnane X receptor (Du, Je > Il, Col > St), peroxisome proliferator-associated receptor gamma (St, Du, Col > Je, Il), constitutive androstane receptor (Je, Du > Il, Col), and retinoid x receptor alpha (Du > Il)] and NR target genes [glutathione-S-transferase A3-3 (Du > Je > St, Il; St > Col), phenol-sulfating phenol sulfotransferase 1A1 (Du, Je > Il, St; Col > St), cytochrome P450 3A12 (Du, Je > St, Il, Col), multiple drug resistance gene 1 (Du, Je, Il, Col > St), multiple drug resistance-associated protein 2 (Je, Du > Il > St, Col), multiple drug resistance-associated protein 3 (Col > St > Il; Du > Je, Il; St > Il), NR corepressor 2 (St > Il, Col), and cytochrome P450 reductase (St, Du, Je > Il, Col)], but not for peroxisome proliferator-associated receptor alpha. Differences (P > 0.05) in mRNA abundance in the liver relative to the GIT were also observed. In conclusion, the presence of numerous differences in expression of NR and NR target genes in different parts of the GIT and in liver of healthy dogs may be associated with location-specific functions and regulation of GIT regions.

Effects of vasopressin on microcirculatory blood flow in the gastrointestinal tract in anesthetized pigs in septic shock

BACKGROUND: Vasopressin increases arterial pressure in septic shock even when alpha-adrenergic agonists fail. The authors studied the effects of vasopressin on microcirculatory blood flow in the entire gastrointestinal tract in anesthetized pigs during early septic shock. METHODS: Thirty-two pigs were intravenously anesthetized, mechanically ventilated, and randomly assigned to one of four groups (n=8 in each; full factorial design). Group S (sepsis) and group SV (sepsis-vasopressin) were made septic by fecal peritonitis. Group C and group V were nonseptic control groups. After 300 min, group V and group SV received intravenous infusion of 0.06 U.kg.h vasopressin. In all groups, cardiac index and superior mesenteric artery flow were measured. Microcirculatory blood flow was recorded with laser Doppler flowmetry in both mucosa and muscularis of the stomach, jejunum, and colon. RESULTS: While vasopressin significantly increased arterial pressure in group SV (P<0.05), superior mesenteric artery flow decreased by 51+/-16% (P<0.05). Systemic and mesenteric oxygen delivery and consumption decreased and oxygen extraction increased in the SV group. Effects on the microcirculation were very heterogeneous; flow decreased in the stomach mucosa (by 23+/-10%; P<0.05), in the stomach muscularis (by 48+/-16%; P<0.05), and in the jejunal mucosa (by 27+/-9%; P<0.05), whereas no significant changes were seen in the colon. CONCLUSION: Vasopressin decreased regional flow in the superior mesenteric artery and microcirculatory blood flow in the upper gastrointestinal tract. This reduction in flow and a concomitant increase in the jejunal mucosa-to-arterial carbon dioxide gap suggest compromised mucosal blood flow in the upper gastrointestinal tract in septic pigs receiving low-dose vasopressin.

T cell-mediated immunoregulation in the gastrointestinal tract

In the intestinal tract, only a single layer of epithelial cells separates innate and adaptive immune effector cells from a vast amount of antigens. Here, the immune system faces a considerable challenge in tolerating commensal flora and dietary antigens while preventing the dissemination of potential pathogens. Failure to tightly control immune reactions may result in detrimental inflammation. In this respect, 'conventional' regulatory CD4(+) T cells, including naturally occurring and adaptive CD4(+) CD25(+) Foxp3(+) T cells, Th3 and Tr1 cells, have recently been the focus of considerable attention. However, regulatory mechanisms in the intestinal mucosa are highly complex, including adaptations of nonhaematopoietic cells and innate immune cells as well as the presence of unconventional T cells with regulatory properties such as resident TCRgammadelta or TCRalphabeta CD8(+) intraepithelial lymphocytes. This review aims to summarize the currently available knowledge on conventional and unconventional regulatory T cell subsets (Tregs), with special emphasis on clinical data and the potential role or malfunctioning of Tregs in four major human gastrointestinal diseases, i.e. inflammatory bowel diseases, coeliac disease, food allergy and colorectal cancer. We conclude that the clinical data confirms some but not all of the findings derived from experimental animal models.

MODELING SPORADIC TUMOR FORMATION DRIVEN BY TELOMERE DYSFUNCTION IN THE GASTROINTESTINAL TRACT

Colorectal cancer is a complex disease that is thought to arise when cells accumulate mutations that allow for uncontrolled growth. There are several recognized mechanisms for generating such mutations in sporadic colon cancer; one of which is chromosomal instability (CIN). One hypothesized driver of CIN in cancer is the improper repair of dysfunctional telomeres. Telomeres comprise the linear ends of chromosomes and play a dual role in cancer. Its length is maintained by the ribonucleoprotein, telomerase, which is not a normally expressed in somatic cells and as cells divide, telomeres continuously shorten. Critically shortened telomeres are considered dysfunctional as they are recognized as sites of DNA damage and cells respond by entering into replicative senescence or apoptosis, a process that is p53-dependent and the mechanism for telomere-induced tumor suppression. Loss of this checkpoint and improper repair of dysfunctional telomeres can initiate a cycle of fusion, bridge and breakage that can lead to chromosomal changes and genomic instability, a process that can lead to transformation of normal cells to cancer cells. Mouse models of telomere dysfunction are currently based on knocking out the telomerase protein or RNA component; however, the naturally long telomeres of mice require multiple generational crosses of telomerase null mice to achieve critically short telomeres. Shelterin is a complex of six core proteins that bind to telomeres specifically. Pot1a is a highly conserved member of this complex that specifically binds to the telomeric single-stranded 3’ G-rich overhang. Previous work in our lab has shown that Pot1a is essential for chromosomal end protection as deletion of Pot1a in murine embryonic fibroblasts (MEFs) leads to open telomere ends that initiate a DNA damage response mediated by ATR, resulting in p53-dependent cellular senescence. Loss of Pot1a in the background of p53 deficiency results in increased aberrant homologous recombination at telomeres and elevated genomic instability, which allows Pot1a-/-, p53-/- MEFs to form tumors when injected into SCID mice. These phenotypes are similar to those seen in cells with critically shortened telomeres. In this work, we created a mouse model of telomere ysfunction in the gastrointestinal tract through the conditional deletion of Pot1a that recapitulates the microscopic features seen in severe telomere attrition. Combined intestinal loss of Pot1a and p53 lead to formation of invasive adenocarcinomas in the small and large intestines. The tumors formed with long latency, low multiplicity and had complex genomes due to chromosomal instability, features similar to those seen in sporadic human colorectal cancers. Taken together, we have developed a novel mouse model of intestinal tumorigenesis based on genomic instability driven by telomere dysfunction.

Effects of increasing levels of pea hulls in the diet on productive performance, development of the gastrointestinal tract, and nutrient retention of broilers from one to eighteeen days of age

The effects of inclusion of pea hulls (PH) in the diet on growth performance, development of the gastrointestinal tract and nutrient retention were studied in broilers from 1 to 18d of age. There were a control diet based on low fibre ingredients (69.3 total dietary fibre (16.1g crude fibre/kg)) and three additional diets that resulted from the dilution of the basal diet with 25, 50 and 75g PH/kg (81.2, 93.2, and 105.1g total dietary fibre/kg diet, respectively). Each treatment was replicated six times and the experimental unit was a cage with 12 chicks. Growth performance, development of the gastrointestinal tract and the coefficients of total tract apparent retention (CTTAR) of nutrients were recorded at 6, 12 and 18d of age. In addition, jejunal morphology was measured at 12 and 18d and the coefficients of apparent ileal digestibility (CAID) of nutrients at 18d of age. Pea hulls inclusion affected all the parameters studied. The inclusion of 25 and 50g PH/kg diet improved growth performance as compared to the control diet. The relative weight (g/kg body weight) of proventriculus (P≤0.01), gizzard (P≤0.001) and ceca (P≤0.05) increased linearly as the level of PH in the diet increased. The inclusion of PH affected quadratically (P≤0.01) villus height:crypt depth ratio with the highest value shown at 25g PH/kg. In general, the CTTAR and CAID of nutrients increased linearly and quadratically (P≤0.05) with increasing levels of PH, showing maximum values with PH level between 25 and 50g/kg diet. We conclude that the size of the digestive organs increases with increasing levels of PH in the diet. In general, the best performance and nutrient digestibility values were observed with levels of PH within the range of 25 and 50g/kg. Therefore, young broilers have a requirement for a minimum amount of dietary fibre. When pea hulls are used as a source of fibre, the level of total dietary fibre required for optimal performance is within the range of 81.2–93.2g/kg diet (25.6–35.0g crude fibre/kg diet). An excess of total dietary fibre (above 93.2g/kg diet) might reduce nutrient digestibility and growth performance to values similar to those observed with the control diet.

Factores nutricionales que influyen sobre las variables productivas y el desarrollo del tracto gastrointestinal en pollitas comerciales rubias = Nutritional factors affecting productive performance and gastrointestinal tract traits in commercial brown-egg laying pullets

El objetivo general de esta Tesis doctoral fue estudiar la influencia de diversos factores nutricionales sobre los parámetros productivos y el desarrollo del tracto digestivo de pollitas rubias destinadas a la producción de huevos comerciales. Para alcanzar este objetivo se realizaron tres experimentos donde se estudió el cereal principal, el tamaño de partícula del cereal y el nivel de energía y la presentación de los piensos. En el experimento 1 se estudió la influencia del cereal (piensos con enzimas) y la presentación del pienso sobre los parámetros productivos y las características del tracto digestivo en 576 pollitas rubias de 1 a 120 d de edad. De 1 a 45 d de la edad, se utilizaron 4 piensos experimentales organizados de forma factorial con 2 cereales al 50% de inclusión (maíz vs. trigo) y 2 presentaciones del pienso (harina vs. gránulo de 2- mm de diámetro). Cada tratamiento se replicó 6 veces (24 pollitas por réplica). De 46 a 120 d de edad todas las dietas (maíz o trigo) se ofrecieron en harina y por tanto, la única diferencia entre tratamientos fue el cereal utilizado. De 1 a 120 d de edad, las pollitas que recibieron los piensos basados en maíz tuvieron una ganancia de peso vivo (PV) superior (P < 0,05) que las que recibieron los piensos basados en trigo, pero el índice de conversión (IC) fue similar para ambos grupos. De 1 a 45 d de edad, las pollitas alimentadas con gránulo consumieron más pienso (P < 0,001) y tuvieron una ganancia de peso superior (P < 0,001) que las pollitas alimentadas con harina. Gran parte de los efectos beneficiosos de la granulación sobre los parámetros productivos se mantuvieron al final de la prueba (120 d de edad). A los 45 d de edad, el peso relativo de la molleja (PR; g/kg PV) fue superior (P < 0,01) en pollitas alimentadas con maíz que en pollitas alimentadas con trigo. La alimentación en gránulo redujo el PR del tracto gastro intestinal (TGI) y de la molleja (P < 0,001), así como la longitud relativa (LR; cm/kg PV) del intestino delgado (P< 0.01) a ambas edades (45 y 120 d de edad). El tipo de cereal utilizado no afectó al pH del contenido de la molleja a 120 d de edad pero fué inferior (P < 0,01) en las pollitas que recibieron el pienso en harina de 1 a 45 d de la edad que en las que recibieron el pienso en gránulo. Se concluye que el trigo puede substituir al maíz en piensos para pollitas si se acepta una ligera reducción en la ganancia de peso. Asímismo, la alimentación en gránulo de 1 a 45 d de edad aumentó la ganancia de peso a esta edad y al final de la prueba, así como el pH de la molleja a 120 d de edad. La presentación del pienso en gránulo redujo el PR de la molleja y la LR del TGI a 120 d de edad. En el experimento 2 se utilizaron un total de 864 pollitas rubias Hy-Line de 1 d de edad para estudiar la influencia del cereal de la dieta (500 g de maíz o trigo/kg) y el tamaño de partícula del mismo (molienda con molino de martillos con un diámetro de criba de 6, 8, o 10-mm) sobre los parámetros productivos y las características del TGI de 1 a 120 d de edad. Cada uno de los 6 tratamientos se replicó 6 veces (24 pollitas por réplica). De 1 a 45 d de edad, la ganancia de PV aumentó (P< 0,001) y el IC se mejoró (P < 0,05) al reducir el tamaño de partícula del cereal, pero no se observaron diferencias en el periodo crecimiento de 45 a 120 d de edad. A los 45 d de vida, las pollitas alimentadas con maíz tendieron (P < 0,10) a tener un mayor PR del TGI y del proventrículo y una mayor LR del intestino delgado que las pollitas alimentadas con trigo. Asímismo, el PR del TGI a esta edad, aumentó (P < 0,05) a medida que aumentaba el tamaño de partícula del cereal utilizado. A los 120 d de edad, el tratamiento no afectó el PR de ninguno de los órganos del TGI ni al pH de la molleja. Sin embargo, la LR del intestino delgado fue superior (P < 0,05) para las pollitas alimentadas con trigo que para las pollitas alimentadas con maíz. La LR del TGI se redujó (P < 0,05) al aumentar el tamaño de partícula del cereal. Se concluye que el trigo puede incluirse 500 g/kg en piensos de pollitas de 1 a 120 días de edad y que el tamaño de partícula de los cereales afecta el crecimiento de las pollitas durante los primeros 45 d de vida, pero no después. Por lo tanto, se recomienda moler el cereal utilizado al inicio del período de recría (1 a 45 d de edad) con una criba de diámetro igual o inferior a 8 mm. En el experimento 3 se utilizaron un total de 1.152 pollitas rubias Hy-Line de 1 d de edad para estudiar la influencia del nivel de energía de la dieta y la presentación del pienso sobre la productividad y las características del TGI. De 1 a 45 d de edad se utilizaron 6 piensos organizados de forma factorial con 3 concentraciones energéticas (baja: 11,44 MJ; media: 12,05 MJ y alta: 12,66 MJ/kg) y 2 presentaciones del pienso (harina vs. gránulo). De 45 a 120 d todos los piensos experimentales se suministraron en forma de harina y por tanto, la única diferencia entre tratamientos fue el nivel de EMAn utilizado. Cada uno de los 6 tratamientos se replicó 8 veces y la unidad experimental fue la jaula con 24 pollitas. De 1 a 120 d de edad, la ganancia de PV y el IC mejoraron a medida que aumentó la EMAn del pienso (P < 0,001). Las pollitas alimentadas con gránulo de 1 a 45 d de edad comieron mas y tuvieron una ganancia de peso superior (P < 0,001) que las alimentadas con harina. En el global de la prueba, la ganancia de PV fue mayor (P < 0,01) para las pollitas alimentadas con piensos en gránulo. A los 45 d de edad, el PR de todos los segmentos del TGI estudiados fue inferior para las pollitas alimentadas con piensos de alta energía que para las pollitas alimentadas con piensos de media o baja energía. A 120 d de edad, el PR de la molleja fue superior (P < 0,01) para las pollitas alimentadas con piensos de baja energía que con los otros piensos. Sin embargo, la LR del TGI no se vió afectada por el nivel de energía de los piensos. A los 45 d de edad, la alimentación con gránulo redujo el PR del proventrículo (P < 0,05), de la molleja (P < 0,001) y del TGI (P < 0.001), así como la LR del intestino delgado (P < 0,05) y de los ciegos (P < 0,001). A pesar de que las pollitas solo recibieron los piensos en gránulo durante los primeros 45 d de vida, la alimentación con gránulos redujo el PR de la molleja y del proventrículo a 120 d de edad. Se concluye que la alimentación con gránulos durante los primeros 45 d de vida mejora el consumo de pienso y el PV de las pollitas a 120 d de edad. Un aumento del nivel de energía de la dieta de 12,0 a 12,7 MJ/kg mejora los parámetros productivos de 1 a 120 d de edad pero reduce el tamaño del proventrículo y de la molleja. En base de estos resultados concluimos que maíz y trigo con enzimas pueden utilizarse indistintamente en piensos para pollitas de 1 a 120 d de edad con sólo una ligera disminución del PV final con trigo. La granulación y la reducción del tamaño de partícula del cereal del pienso de primera edad (1 a 45 d de vida) y el uso de piensos de alta densidad energética, mejoran los PV a 120 d de edad. Por lo tanto, es recomendable moler los cereales con cribas de no más de 8-mm de diámetro. También, la granulación del pienso y el uso de piensos de alta energía (pobres en fibra bruta) pueden reducir el desarrollo del TGI especialmente de la molleja, lo que puede perjudicar el consumo posterior de pienso durante el inicio del ciclo de puesta. ABSTRACT The general objective of this Thesis was to study the effect of different nutritional factors on productive performance and the development of the gastrointestinal tract (GIT) of commercial brown egg-laying pullets from 1 to 120 d of age. In this respect, the influence of type and particle size of the cereal, and feed form, and energy content of the die,t were studied in 3 experiments. In experiment 1, the influence of the main cereal and feed form of the diet on performance and GIT traits was studied in 576 brown-egg laying pullets from 1 to 120 d of age. From 1 to 45 d of age, 4 diets arranged factorially with 2 cereals (maize vs. wheat) and 2 feed forms (mash vs. pellets) were used. Each treatment was replicated 6 times (24 pullets per replicate). From 46 to 120 d of age, all diets were offered in mash form and therefore, the only difference among diets was the cereal used. Cumulatively, pullets fed the maize diets had higher body weight (BW) gain (P< 0.05) but similar feed conversion ratio (FCR) than pullets fed the wheat diets. From 1 to 45 d of age, pullets fed pellets consumed more feed (P < 0.001) and had higher BW gain (P < 0.001) than pullets fed mash. Most of the beneficial effects of pelleting on productive performance of the birds were still evident at 120 d of age. At 45 d of age, gizzard relative weight (RW; g/kg BW) was higher (P < 0.01) in pullets fed maize than in pullets fed wheat. Feeding pellets reduced the RW of the GIT and the gizzard (P < 0.001) as well as the relative length (RL; cm/kg BW) of the small intestine (SI, P < 0.01) at both ages. The pH of the gizzard contents at 120 d of age was not affected by the main cereal of the diet, but was lower in pullets fed mash from 1 to 45 d of age (P < 0.01) than in pullets fed pellets. We conclude that wheat supplemented with enzymes can be used in substitution of maize in pullet diets with only a slight reduction in BW gain at 120 d of age. Also, feeding pellets from 1 to 45 d of age increased BW gain and pH of the gizzard, and reduced the RW of the gizzard and the RL of the GIT at 120 d of age. In experiment 2, a total of 864 brown-egg laying pullets was used to study the effects of the main cereal of the diet (500 g maize or wheat/kg) and particle size of the cereal (hammer milled to pass through a 6, 8, and 10-mm screen) on growth performance and GIT traits from 1 to 120 d of age. Each of the 6 treatments was replicated 6 times (24 pullets per replicate). Type of cereal did not affect pullet performance at any age. From 1 to 45 d of age, BW gain was increased (P < 0.001) and FCR was improved (P < 0.05) as the particle size of the cereal was reduced, but no effects were observed after this age. At 45 d of age, pullets fed maize tended (P < 0.10) to have a heavier RW of the GIT and proventriculus and a higher relative length (RL, cm/kg BW) of the SI than pullets fed wheat. Also at this age, the RW of the GIT increased (P < 0.05) with increases in particle size of the cereal. At 120 d of age, dietary treatment did not affect the RW of any of the organs studied or gizzard pH, but the RL of the SI was higher (P < 0.05) for pullets fed wheat than for pullets fed maize. Also, the RL of the SI was reduced (P < 0.05) as the particle size of the cereal increased. We conclude that 500 g wheat/kg can be included in pullet feeds from 1 to 120 d of age, and that particle size of the cereal affects pullet performance during the first 45 d of life but not thereafter. Therefore, it is recommended to grind the cereal used in this period with a screen size of no more than 8-mm. In experiment 3, a total of 1,152 one-day-old Hy-Line Brown egg laying pullets were used to study the influence of the energy content of the diet and feed form on productive performance and on several GIT traits. From 1 to 45 d of age, there were 6 diets arranged factorially with 3 concentrations of AMEn (low: 11.66 MJ/kg, medium: 12.05 MJ/kg and high: 12.66 MJ/kg) of the diet and 2 feed forms (mash vs. pellets). From 45 to 120 d all diets were fed in mash form and therefore, the only difference among treatments in this period was the energy content of the diets. Each of the 6 treatments was replicated 8 times and the experimental unit was formed by 24 pullets. Cumulatively, BW gain and FCR improved as the AMEn of the diet increased (P < 0.001). Also, pullets fed pellets from 1 to 45 d of age had higher feed intake and BW gain (P < 0.001) in this period and higher cumulative BW gain (P < 0.01) than pullets fed mash. At 45 d of age, the RWof all the segments of the GIT was lower for pullets fed the high- than for pullets fed the medium- or low- energy diets. At 120 d of age, the RW of the gizzard was higher (P < 0.01) for pullets fed the low energy diets than for pullets fed the other diets. However, the RL of the GIT was not affected by the energy content of the diet. Feeding pellets reduced the RW of the proventriculus (P < 0.05), gizzard (P < 0.001), and GIT (P < 0.001), as well as the RL of the small intestine (P < 0.05) and the ceaca (P < 0.001) at 45 d of age. The effects of feeding pellets on RW of gizzard and proventriculus were still evident at 120 d of age. We concluded that feeding pellets from 1 to 45 d of age improved feed intake and BW of pullets at 120 d of age and that an increase in the energy content of the diet increased pullet performance at all ages but reduced the RW of the proventriculus and gizzard. We conclude that maize and wheat can be used indistinctly in diets for egg laying pullets from 1 to 120 d of age, with only a slight reduction in final BW when wheat is used. Also, particle size of the cereal affects pullet performance during the first 45 d of life but not thereafter. Pelleting of the feeds, and grinding the cereal with a screen size of no more than 8-mm from 1 to 45 d of age, and the use of high density energy diets are recommended in order to achieve adequate target BW at 120 d of age. However, pelleting of the feed, very fine grinding, and the use of high AMEn diets might hinder the development of the GIT, especially that of the gizzard, which might affect feed intake of laying hens especially at the beginning of the production cycle.

The genetic diversity of lactic acid producing bacteria in the equine gastrointestinal tract

Seventy-two lactic acid producing bacterial isolates (excluding streptococci) were cultured from the gastrointestinal tract of six horses. Two of the horses were orally dosed with raftilose to induce lactic acidosis and laminitis while the remaining four were maintained on a roughage diet. Near complete 16S rDNA was amplified by PCR from the genomic DNA of each isolate. Following RFLP analysis with the restriction enzymes MboI, HhaI and HinfI, the PCR products from the IS isolates that produced L- and/or D-lactate were subsequently cloned and sequenced. DNA sequence analysis indicated that the majority of the isolates were closely related to species within the genus Lactobacillus, including Lactobacillus salivarius, Lactobacillus mucosae and Lactobacillus delbrueckii. Four isolates were closely related to Mitsuokella jalaludinii. Lactic acid producing bacteria (LAB) from the equine gastrointestinal tract was dominated by representatives from the genus Lactobacillus, but also included D-lactate-producing bacteria closely related to M. jalaludinii. Identification and characterization of LAB from the equine gastrointestinal tract should contribute to our understanding and management of fermentative acidosis, ulceration of the stomach and laminitis. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Comparative ultrasonographic investigations of the gastrointestinal tract and the liver in healthy and diseased pigeons

The use of ultrasound as a diagnostic tool in birds has been documented for cardiac, urogenital, and liver disease. However, its use in gastrointestinal tract disease is not defined. Therefore, the purpose of this study was to compare the ultrasonographic findings of the intestine and liver of six healthy racing pigeons with those of six racing pigeons with gastrointestinal disease. The echogenicity of the liver was significantly different between the two groups. Pigeons with gastrointestinal disease had less homogeneous liver echogenicity with focal heterogeneous areas and the hepatic blood vessels were visible and dilated. The duodenum was visualized and its mean diameter of 7.2 +/- 0.3 mm in the diseased pigeons was significantly wider (P < 0.001) than the 5.7 +/- 0.2 mm in healthy birds. The thickness of the duodenal wall in healthy and diseased pigeons was 1.6 +/- 0.1 and 2.4 +/- 0.1 mm, respectively, and they were significantly different (P < 0.001). We defined baseline measurements for the duodenal loop in pigeons and provided evidence that ultrasound can be a useful diagnostic tool for investigating intestinal disease in pigeons.