<p>Gastrointestinal health in the young pig is a constant challenge for the swine industry. Weaning introduces many stressors such as a new solid diet, being separated from their mother, new pen mates, transportation, and an entirely new environment. Therefore, this dissertation primarily focuses on research aiding the pig immediately post-weaning. In chapter 2, a developmental bacillus direct fed microbial (DFM) was added to nursery pig diets to evaluate its effects on pig growth and health in two 35-d experiments, both randomized complete block designs based on initial BW and sex. Experiment 1 used 376 weaned pigs (17.8 d of age; 5.99±0.18 kg initial BW) allotted to one of four diets. 1) Negative Control (NC; no antibiotics with pharmacological Zn or Cu), 2) NC+DFM 0.275x109 CFU, 3) NC+DFM 0.55x109 CFU, 4) NC+DFM 1.1x109 CFU. Experiment 2 used 420 weaned pigs (20.1 d of age; 6.11±0.34 kg initial BW) allotted to one of four diets: 1) Negative Control (NC; no antibiotics with pharmacological Zn or Cu), 2) NC+DFM 0.55x109 CFU, 3) NC+DFM 1.1x109 CFU, 4) NC+BioPlus 2B 1.1x109 CFU. Experiment 1; during week 1 there were no treatment effects. During week 3 ADFI (P=0.053) quadratically increased while G:F (P=0.028) quadratically decreased as DFM increased in the diet. During d21-35 of experiment 2, ADG (P=0.092) quadratically increased and G:F (P=0.014) quadratically decreased as DFM increased.  Overall, for Experiment 1, ADFI numerically increased (4.3%) with no increase in ADG, resulting in a quadratic decrease in G:F (P=0.010) as the DFM increased in the diet.  For Experiment 2, during week 1, DFM fed pigs tended to have linearly decreased ADFI (P=0.092) and linearly increase G:F (P=0.072). Pigs fed the Bioplus2B bacillus had greater ADFI (P=0.018) than the same dose of the experimental bacillus. During week 2 pigs fed the experimental bacillus at 1.1x109 CFU tended to have improved G:F (P=0.084) than the similar DFM concentration from, the Bioplus 2B. During week 4 ADG tended to linearly (P=0.057) improve with increasing DFM in the diet and the average of all DFMs tended to have improved ADG (P=0.075) over the NC. During week 5 ADFI linearly increased (P=0.029) as DFM increased in the diet and all DFM treatments had greater ADFI (P=0.009) than the NC.  During d 21-35 of experiment 2, DFM fed pigs had linearly increased ADG (P=0.04) and ADFI (0.090). All pigs fed DFM had improved ADG (P=0.068) and ADFI (P=0.032) compared to NC fed pigs. Summarizing these two studies, the DFM product had its greatest effect improving gain feed intake and efficiency during late nursery when simplest diets are fed.</p> <p>In chapter 3, Dacitic tuff breccia (DTB) and poultry by-products (PBP) were added to nursery pig diets to evaluate their effects on growth performance and jejunal characteristics in a 35 d experiment. PBP were added as a replacement for fishmeal and was expected to provide an increased immune challenge to the newly weaned pigs. DTB was added as a functional trace element source and was hypothesized to ameliorate some of the negative impacts of PBP on the gut. A randomized complete block design based on BW and sex was used. Newly weaned pigs (N=564, 20.1±1.2 d of age, 6.18±1.13 kg initial BW). allotted to four diets (15 replicates/treatment; 9 or 10 pigs/pen): 1) Control (C; no DTB or PBP), 2) C+DTB (0.5% inclusion), 3) C+PBP (4% chicken by-product meal + 2% feather meal – replacing fishmeal, corn, and synthetic amino acids in the C), 4) C+DTB+PBP. Phase 1-3 were each 7-d and Phase 4 was from d 21-35. One barrow/pen was harvested 11d post-weaning. Jejunal tissue and mucosa were collected for histological measures and gene expression. In week 2, pigs fed DTB tended to increase ADG (323 vs. 303 g/d; P=0.068) and ADFI (376 vs. 356 g/d; P=0.055) compared to pigs not fed DTB and pigs fed PBP tended to have increased ADG (P=0.093). In week 3 pigs fed PBP had reduced ADG (460 vs 483 g/d; P=0.011) and G:F (0.689 vs. 0.723; P<0.001), and there tended to be an interaction for G:F (P=0.083) with DTB improving G:F when fed in combination with PBP but reducing G:F in the control diet.  In week 4, feeding PBP decreased ADG (384 vs 415 g/d; P<0.01) and ADFI (629 vs 666 g/d; P<0.01) compared to pigs fed no PBP.  For Phase 4 (d21-35) pigs fed PBP had decreased ADG (479 vs 497 g/d; P=0.041) and tended to have reduced ADFI (P=0.092) compared to pigs fed no PBP. Overall (d 0-35), there were no significant differences among treatments in pig growth performance.   Pigs fed PBP had increased jejunal expression of interferon-alpha (P=0.041) and interleukin-10 (P=0.037) and tended to have increased expression of claudin-1 (P=0.076).  Pigs fed DTB tended to have decreased jejunal expression of interferon-gamma (P=0.079).  Jejunal gene expression of tumor necrosis factor-alpha and nuclear factor kappa-beta did not differ among treatments. In conclusion, DTB improved nursery pig growth performance early and pigs fed PBP had decreased ADG and feed efficiency late in the nursery period. Feeding PBP had minimal effects on jejunum architecture but increased the gut immune response.</p> <p>Chapter 4 focuses on weaning age in addition to dietary treatments. Changes in weaning age and diet complexity can impact pig growth post-weaning. 432 weanling gilts and barrows (Topigs Duroc Ⅹ (US York X Landrace)) from the same farrowing group were utilized for a 30 or 35 d growth trial to compare early (EW) versus late weaning (LW) and high or low levels of specialty proteins in nursery diets. 216 pigs were EW (18 or 19 d, avg. age=18.4 days, avg. BW=5.96 kg) and 216 pigs were LW 5 days later (24, 25 or 26 d, avg. age=24.6 d, avg. BW=7.50 kg). At weaning pigs were blocked by weaning age, BW, sex and litter, and randomly allotted to 48 pens with 9 pigs/pen. Pigs at each weaning age were fed a High Complexity (HC) or a Low Complexity (LC) diet. The trial was conducted as a 2X2 factorial design: 1) EW+HC; 2) EW+LC; 3) LW+HC; 4) LW+LC. Pigs and feeders were weighed on d 0, 7, 14, 21, 28, and 35 for EW, and on d 0, 7, 14, 21, 28, and 30 for LW.  LW pigs had improved ADG and ADFI from d 0-7, 7-14, 14-21, and the final week of the nursery (P<0.05). G:F decreased for LW pigs from d 21-28 (P<0.01) compared to EW pigs, however for the overall nursery trial LW pigs had increased G:F (P=0.01). LW pigs had increased overall nursery ADG vs EW pigs (452.5 g/d vs 400 g/d; P<0.01). End of nursery BW was greater for LW vs EW pigs (21.70 kg vs 20.74 kg; P=0.001).  There was a weight block by weaning age interaction, EW heavy pigs had lower ADG compared to LW heavy pigs, however when comparing light weight pigs, the EW light pigs had improved ADG compared to LW light weight pigs (P=0.017). EW pigs were lighter at market (approximately d146 of age) compared to LW pigs (120.78 vs 124.16 kg; P=0.014). An interaction between weaning age, nursery diet, and sex (P<0.07) was observed for market weight, EW barrows fed LC diets were lighter at market (120.77 kg) than EW barrows fed HC diets (126.54 kg).  Whereas for LW barrows fed LC had higher market weights (130.04 kg) than LW barrows fed HC diets (127.59 kg). A similar, but non-significant pattern was observed for gilts. Weaning age and feeding pigs the correct diet for their age in the nursery can have a lifelong effect on the pig. </p> <p>In conclusion, feeding a DFM containing bacillus licheniformis did not impact nursery pig growth performance early in the nursery period. From d21-35 ADG and ADFI was improved in both experiments 1 and experiment 2. While the growth results were sporadically improved throughout the nursery period, the DFM’s greatest effect was it ability to improve ADFI. The improvement in the late nursery phase may be due to the need for the DFM to establish itself in the GIT. DTB tended to improve ADG and ADFI in week 2 of the nursery period, however there were no differences for growth overall. PBP reduced ADG in week 3 of the nursery period, as well as reduced ADG and ADFI in week 4 of the nursery. While there were differences in individual weeks of the trial there were no overall differences in growth performance. However, when looking at gene expression in the jejunum at d11 post-weaning, there was an increase in IFN-α and IL-10 in pigs fed PBP. In pigs fed DTB there was a decrease in IFN-γ jejunal gene expression as well. Feeding a high complexity and low complexity diet had no impact on the nursery pigs growth performance, in hindsight the low complexity diet was perhaps not low enough in specialty proteins. When comparing weaning age, pigs weaned later had increased ADG and ADFI from d0-21 post-weaning. For the overall nursery performance, LW pigs had a higher ADG, and ended the nursery period 0.96 kg heavier than the EW pigs. Comparing pigs of similar bodyweight at weaning, EW pigs were 1.5 kg heavier than LW pigs at the end of the nursery period, but the LW pigs were more feed efficient. There was a weight block by weaning interaction in this trial, as the heaviest LW pigs had higher ADG compared to the heaviest EW pigs. However, when looking at the lightest pigs, the EW pigs outperformed the LW pigs. Looking at market weights of each age group, LW pigs were 3.5 kg heavier on average at d146 of age. Although there was not a difference in diet found in the nursery phase, interestingly there were interactions discovered between treatments at market weight. Barrows are more sensitive to nursery diet compared to gilts, as LW barrows fed the low complexity diet performed better than the LW high complexity fed barrows. EW barrows were heavier at market when fed the high complexity diet, compared to EW barrows fed the low complexity diet. This shows that while the diet didn’t appear to have an impact in the nursery, feeding the pig the proper diet for their age has a lifelong impact on the pig.</p>

Ischemic colitis is a known complication of abdominal aortic aneurysm (AAA) repair. There is still no established consensus regarding the individual significance of factors related to this phenomenon. We detail the hospital course of a patient who unexpectedly developed acute colonic ischemia following open AAA repair. The pathophysiology, diagnostic modalities, potential preventative measures, and effect on patient morbidity and mortality will be presented. Reviewing the current literature, this will focus on the reported statistical importance of various risk factors including the incidence following traditional open repair and endovascular aneurysm repair.

Hepatitis C is the most common chronic bloodbourne infection in the United States, with an estimated prevalence of 2.7 million. The total cost of care for this patient population was estimated to be $6.5 billion in 2013. Since 1998, the Centers for Disease Control (CDC) have recommended hepatitis C screening for specific high risk populations, but until recently there was no recommendation for age-based screening. The recent advent of new, more efficacious therapies for hepatitis C have made early identification significantly more important. Consequently, the CDC updated its recommendations in 2012 based on recent evidence to include one-time screening for all individuals born between 1945 and 1965. In 2013, the US Preventive Services Task Force (USPSTF) also incorporated this recommendation into their hepatitis C screening guidelines. In spite of this, there is some debate in the medical community regarding cohort screening for hepatitis C, and some data indicates widespread misunderstanding of current screening recommendations among primary care providers. The purpose of this project was to evaluate current knowledge and understanding of hepatitis C screening guidelines among a group of family medicine residents at East Tennessee State University, and to improve their knowledge in order to promote more appropriate screening practices in their patient population. To accomplish this, 13 question surveys were administered to residents to assess their current knowledge. Following these surveys, residents attended an education session covering current recommendations from the CDC and USPSTF. The 13 question survey was administered again in the post-intervention period. A t-test revealed that post-intervention survey scores increased significantly on 8 out of 13 questions. The intervention was successful at improving knowledge of current hepatitis C screening recommendations in the target population. Future research should be directed at broadening the intervention to include a variety of other providers, and at assessing the impact on execution of screening in the patient population, particularly regarding application to people born in the specified birth cohort.

Oral iron replacement therapy is often used as a first-line modality for the treatment of iron deficiency anemia (IDA). Oral iron replacement options include tablets, capsules, and liquid formulations. Esophagitis due to iron tablet administration is a well-documented phenomenon, yet peptic ulcer disease secondary to iron tablet administration is less well-known. An 83-year-old female with a past medical history of chronic kidney disease stage V, anemia of inflammatory disease, heart failure with preserved ejection fraction, and gastroesophageal reflux disease presented to the hospital with diffuse abdominal pain and dark red emesis. She was started on ferrous sulfate supplementation two weeks ago and described progressive abdominal pain and nausea since beginning the medication. She was not taking nonsteroidal anti-inflammatories (NSAIDs), antiplatelets, or anticoagulants. Six months ago, she had an unremarkable upper endoscopy performed for new-onset gastroesophageal reflux disease. Laboratory studies revealed a hemoglobin of 7.3 mg/dL and due to a concern for rapid blood loss, she was given one unit of packed red blood cells. A non-contrast computed tomography was performed showing wall thickening of the stomach and the first two portions of the duodenum. A possible ulcer was seen in the distal posterior stomach. The patient was made NPO, and twice daily intravenous pantoprazole was started. An upper endoscopy was performed which revealed a 2.5 cm clean-based ulcer in the duodenal bulb. Biopsies showed acute inflammation and positivity for iron debris but were negative for Helicobacter pylori. Once daily pantoprazole was continued, and her ferrous sulfate tablets were discontinued. Her symptoms did not return. Ferrous sulfate may erode and ulcerate the gastric and duodenal mucosa like that of a chemical burn. Iron deposits may be seen on biopsies performed with Prussian blue staining. Brown crystalline deposits may be seen on hematoxylin and eosin staining. Iron injury may be seen in pill or capsule formulations due to a concentration effect, but this is typically not seen with solution forms. Treatment includes discontinuation of tablet or capsule formulations and substitution with liquid forms.

Complete or partial obstruction of the duodenum by the superior mesenteric artery (SMA) is a rare cause of bowel obstruction. SMA syndrome results from the compression of the 3rd part of the duodenum between the superior mesenteric artery and the abdominal aorta. Causes include anatomical variation in the superior mesenteric artery, trauma, burns, surgeries, malignancy, and rapid weight loss. Diagnosis of SMA syndrome in patients may be difficult, as the clinical findings often resemble other forms of small bowel obstructions. This syndrome was first described in the literature by Carl Freiherr von Rokitansky in 1861. Subsequently, David Wilke provided a comprehensive description of the disease in a series of 75 patients. There has been skepticism about the existence of SMA syndrome due to scant literature reports and non-specific symptomatology. However, modern cross-sectional imaging has confirmed the existence of this rare syndrome. Here we present the case of a 50-year-old female with longstanding symptoms of gastrointestinal discomfort, weight loss, nausea, and vomiting. She underwent an exhaustive gastrointestinal workup until a diagnosis of SMA syndrome was made. We elected to proceed with a minimally invasive three-port laparoscopic, trans-mesenteric side-to-side duodenojejunostomy. The patient was discharged on postoperative day one after tolerating a regular diet. On one month follow-up, our patient reported improvement in symptoms with no postprandial pain or nausea and normal bowel movements. In conclusion, we report a case of superior mesenteric artery syndrome in a patient with recurrent abdominal pain and nausea. CT scan has the highest sensitivity for the diagnosis of SMA syndrome, findings suggestive of the diagnosis include an abnormal aortomesenteric angle and distance. While supplemental tube feeds and gastric drainage may resolve the condition without the need for surgery, this often takes many weeks to months to be effective. Minimally invasive surgical bypass is an attractive option because of the rapidity of symptom resolution, lack of need for long-term invasive tubes, short inpatient length of stay, and high success rate.

Esophageal and biliary stents are indwelling devices used in the treatment of selected gastrointestinal and biliary disorders. Stenting is accepted as a standard procedure for palliation of malignant obstruction of the esophagus and biliary system. Review of the early and late complications associated with these devices is made with emphasis on the clinical and radiographic features. A suggested approach to diagnosis and treatment recommendations are made for each complication that the emergency department physician may encounter.

Inflammatory diseases such as PCOS, autoimmune diseases, irritable bowel syndrome, etc. are all highly uncomfortable diseases with several negative side effects. By adding antioxidants and omega-3 fatty acids to patients with inflammatory diseases diets, studies show that symptoms of these diseases will lessen. The objective of this study is to create a banana bread with increased omega-3 fatty acids and increased antioxidants to be served on trays of patients with inflammatory diseases and for patients to make at home to decrease symptoms related to inflammation. The experimental food should be an equal substitute for the control flavor, aroma, and texture wise. The control banana bread was substituted for an anti-inflammatory banana bread with the addition of cinnamon, dark chocolate, extra eggs, and pecans. The banana bread was made without dairy and grain for celiac patients and lactose intolerant patients. Both variations were equally accepted according to the hedonic scale, completed by 9 participants. Research was continued to confirm the of increased omega-3 fatty acids within the anti-inflammatory bread. Furthermore, walnuts were switched for pecans to test the antioxidant and fatty acid composition of both variations. Overall, we found that the walnut variation had more fatty acids, but pecans had more antioxidants. Our research suggests that both variations can be used to accommodate patients with inflammatory diseases. Further research can be done for long-term research for inflammatory disease patients that swapped the control for the variations.

No description available.

The purpose of this study is to investigate the disappearance of crude fiber and lignin from the digestive tracts of healthy young college women consuming a self-selected diet.

Tesis por compendio / Aunque el uso de altos niveles de fuentes de proteína vegetal en piensos para doradas de engorde se ha alcanzado con éxito en cuanto al crecimiento, estas dietas todavía están asociadas a efectos negativos en la eficiencia nutricional y en la capacidad inmunitaria. El intestino es el órgano donde se produce la primera interacción entre el pez, los nutrientes y las bacterias del medio, y desarrolla un papel crucial en la digestión de los nutrientes y la respuesta infamatoria e inmune. Esta tesis doctoral se centra en el impacto de distintas dietas con altos niveles de proteína vegetal, y especialmente, en la evaluación del estatus intestinal de las doradas de engorde alimentadas con altos niveles de sustitución de la harina de pescado durante un periodo largo de tiempo. Los cambios observados en el intestino se caracterizaron mediante el uso de distintas estrategias, como el análisis de la digestibilidad y la retención de amino ácidos, de la excreción de amonio, de la actividad de enzimas digestivos, de los cambios histológico o de la expresión de genes relacionados con la función y el mantenimiento de la arquitectura intestinal, así como técnicas ómicas para el análisis del proteoma y de la microbiota intestinal. Se ensayaron distintos niveles de sustitución de harina de pescado, pero el impacto de las dietas con una sustitución completa, bien complementada con subproductos de origen marino o suplementada con aminoácidos libres sintéticos, recibió mayor atención. La sustitución completa de la harina de pescado provocó una reducción, aunque ligera, del crecimiento y de la eficiencia digestiva y nutritiva de la dorada de engorde, aunque el impacto sobre el crecimiento era mayor cuando los peces eran alimentados desde la época de juveniles con estas dietas. La digestibilidad y el nivel de síntesis de proteína se vio alterada, aunque no se observaron diferencias significativas en la actividad enzimática digestiva. No obstante, el impacto de las fuentes vegetales cuando no había fuentes de proteína marina en la dieta era especialmente crítico para la supervivencia de los peces. En el intestino de estos peces solo se observaron diferencias menores relacionadas con la inflamación a nivel histológico, pero también se observó una disminución en la expresión génica de genes involucrados en la inflamación y la respuesta inmune. El análisis de la microbiota intestinal reveló cambios significativos en la composición de su composición, especialmente en el intestino posterior, sugiriendo una posible falta de capacidad de regular la respuesta inmune y de modular la colonización de bacterias patógenas tras un largo periodo de alimentación con esta dieta. Por otro lado, el análisis del proteoma de la mucosa intestinal también mostró un claro impacto sobre distintos procesos biológicos relacionados con el mantenimiento del homeostasis intestinal y de la integridad epitelial. Por el contrario, no se observó un impacto de la sustitución de la harina de pescado a nivel de expresión génica o del proteoma cuando se incorporaba a la dieta una fuente de proteína marina complementaria, aunque sí que se observaron algunos signos menores de inflamación. Por último, se desarrolló un sistema ex vivo para estudiar la respuesta inflamatoria e inmune de la mucosa intestinal a la presencia de distintas bacterias, y se realizó un ensayo preliminar en dorada para evaluar el efecto de la dieta sobre esta respuesta. En resumen, en este trabajo se ha realizado una evaluación extensa y detallada de los efectos a nivel intestinal de la inclusión de altos niveles de proteína vegetal en la dieta para doradas de engorde. Los resultados indican que las alteraciones en la capacidad inmune, la homeostasis y la microbiota intestinal aparecían solo cuando la proteína procedía exclusivamente de fuentes vegetales, y podrían explicar la mayor mortalidad registrada con esta dieta. / Malgrat que la utilització d'alts nivells de proteïna vegetal en pinsos per a dorades en la fase d'engreixament s'ha aconseguit amb èxit en quan al creixement, aquestes dietes encara s'associen amb freqüència amb efectes negatius en l'eficiència nutricional i la capacitat immunitària. L'intestí és l'òrgan on es produeix la primera interacció entre el peix, els nutrients de la dieta i les bactèries de l'ambient, i juga un paper fonamental en la digestió dels nutrients i en la resposta inflamatòria i immune. Aquesta tesi doctoral es centra en l'impacte de diferents dietes experimentals amb un alt nivell de proteïna vegetal, i especialment, en l'avaluació de l'estat de l'intestí de les dorades d'engreixament alimentades durant un llarg període amb alts nivells de substitució de farina de peix. Els distints canvis observats a nivell intestinal es van descriure mitjançant l'ús de distintes estratègies, com l'anàlisi de la digestibilitat i la retenció dels aminoàcids, de l'excreció d'amoni i de l'activitat enzimàtica, dels canvis histològic o de l'expressió de gens relacionats amb la funció i el manteniment de l'estructura intestinal, així com tècniques òmiques per a l'anàlisi del proteoma i de la microbiota intestinal. Es van assatjar diferents nivells de substitució de farina de peix, però l'impacte de les dietes amb substitució completa, bé complementada amb subproductes d'origen marí o suplementada amb aminoàcids lliures sintètics, va rebre major atenció. La substitució completa de la farina de peix va tenir un efecte lleugerament negatiu sobre el creixement i l'eficiència digestiva i nutritiva de la dorada d'engreixament, encara que l'impacte era major quan els peixos eren alimentats des de la fase de juvenils amb aquesta dieta. La digestibilitat i el nivell de síntesis de proteïna es va veure alterada, encara que no s'observaren diferències significatives en l'activitat dels enzims digestius. No obstant, l'impacte de les fonts vegetals quan s'eliminaven per complet les fonts de proteïna marina de la dieta era especialment crític en la supervivència dels peixos. En l'intestí d'aquests peixos sols s'observaren xicotets indicis d'inflamació a nivell histològic, però també es va observar una disminució l'expressió de gens involucrats amb el procés inflamatori i la resposta immune. L'estudi de la microbiota intestinal va revelar canvis significatius en la composició, especialment a l'intestí posterior, suggerint una possible falta de capacitat de regular la resposta immunitària i de modular la colonització per part de patògens després d'un llarg període d'alimentació amb aquesta dieta. D'altra banda, l'anàlisi del proteoma de la mucosa intestinal també va mostrar un impacte clar sobre diferents processos biològics relacionats amb el manteniment de l'homeòstasi intestinal i de la integritat de l'epiteli. Per contra, no es van observar un impacte de la substitució de la farina de peix a nivell d'expressió gènica o proteoma quan s'incloïa a la dieta una font complementària de proteïna d'origen marí, encara que sí que s'observaven alguns signes d'inflamació. Per últim, es va desenvolupar un sistema ex vivo per avaluar la resposta inflamatòria i immune de la mucosa intestinal davant la presència de diferents bactèries, i es va realitzar un assaig preliminar per determinar l'efecte de la dieta sobre aquesta resposta. En resum, en aquest treball s'ha realitzat una avaluació extensa i detallada dels efectes a nivell intestinal de la inclusió d'alts nivells de fonts de proteïna vegetal a les dieta per a les dorades d'engreixament. Els resultats indiquen que les alteracions en la capacitat immunitària, l'homeòstasi i la microbiota intestinal eren observades solament quan la proteïna era exclusivament obtinguda de fonts vegetals, i podrien explicar la major mortalitat observada amb aquesta dieta. / Although the inclusion of plant protein sources at high levels in aquafeeds for on-growing gilthead seabream has been successfully achieved on gilthead seabream in terms of growth, these diets are still associated to detrimental effects in feed efficiency and immune capacity. The intestine is the organ where takes place the first interaction of the host with dietary antigen or environmental bacteria, and plays a major role in the digestion of nutrients and the inflammatory and the immune response. The present PhD thesis focus on the impact of classical formulated high plant protein diets on fish performance, but especially, on evaluation of the intestinal status in on-growing fish long-term fed with high levels of fishmeal replacement. Changes at intestinal level were characterized by using different approaches, including protein and amino acid digestibility and retention and ammonia excretion, digestive enzyme activity, histology, expression of genes related with inflammation, immunity, structure and digestion, but also using whole tissue-level techniques for the analysis of the impact on proteome and gut microbiota. Different levels of fishmeal replacement were assayed, although the impact of diets with total replacement, complemented by inclusion of alternative marine by-products or supplemented by free amino acids, received greater attention. Total fish replacement produced a negative but minor impact on the growth and nutritive and digestive performance of on-growing gilthead seabream. Nevertheless, when fish were fed from juvenile stage with plant protein based diets, a higher negative impact in growth terms was noticed. Digestibility and metabolic use of amino acids was altered, but no differences were observed in the digestive enzyme activities. Nonetheless, feeding fish with total dietary fishmeal replacement by plant protein without any marine protein source was especially critical for survival rate. In these fish, gut histological assessment only revealed minor alterations related with an inflammatory response, but gene expression assay showed a down-regulation of several genes involved in the inflammatory and immune response. Moreover, a drastic change in the microbiota composition was observed, especially at the hindgut, revealing a possible lack of capacity to regulate a defensive response and to face with pathogen colonisation after a long-term coupling with these diet. Likewise, gut mucosa proteome analysis also suggests an impact on biological processes related with the maintenance of gut homeostasis and the epithelial integrity. In contrast, total fishmeal replacement did not induce alterations at transcript or proteomic level when diet was complemented with marine ingredients, although some minor inflammatory signs were reported. On the other hand, an ex vivo system to study the inflammatory and immune response of the gut mucosa to the presence of different bacteria was developed, and a preliminary assay evaluating the impact of the diet on this response was performed. To sum up, present works represents a wide assessment at intestinal level of the effects of including plant protein sources at high levels in aqua feeds for on-growing gilthead seabream. Results indicate that alterations in the immune capacity, the gut homeostasis and the microbiota were observed when protein was exclusively provided by plant sources, and could explain the higher mortality reported with this diet. / Estruch Cucarella, G. (2018). ASSESSMENT OF THE LONG-TERM IMPACT OF HIGH PLANT PROTEIN DIETS ON THE INTESTINAL STATUS OF THE ON-GROWING GILTHEAD SEA BREAM (Sparus aurata, L.) [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113063 / Compendio