The aim of this work was to quantify the utilisation by rats and pigs of microbial amino acids synthesised in their gastrointestinal tracts. The method which was developed is based on the oral administration of isotopes in non-amino acid form (15NH4Cl or 14C-polyglucose) and the measurement of the incorporation of these isotopes into the amino acids of the body protein of the animal. Since animals cannot incorporate 15N or 14C into certain of the essential amino acids, labelling of such amino acids is only possible via microbial amino acid synthesis and absorption. To calculate the amount of amino acid absorbed the total amount of labelled amino acid (or total radioactivity in the amino acid) in the body was divided by the enrichment (or specific radioactivity, SRA) of that amino acid in microbial protein. It was shown that germ-free rats fed 15NH4Cl were not able to incorporate inorganic 15N into lysine. Conventional rats, however, showed 15N-incorporation in body lysins. When rats fed 15NH4Cl were prevented from coprophagy they did not incorporate 15N in their body lysine. It was concluded that the utilisation of microbial amino acids in rats occurs exclusively via coprophagy. The estimated absorption of microbial lysine by the conventional rats was 21 mg/kg.75 per day. The direct (non-coprophagic) uptake of microbial amino acids in pigs was also measured. Pigs (prevented from coprophagy) were offered a low-protein diet containing 15NH4Cl and 14C-polyglucose. At the end of the experiment the 15N-enrichment of body lysine and the 14C SRA of lysine, histidine, tyrosine, phenylalanine, valine, isoleucine and acids of the microbial fractions of ileal and caecal digesta were also measured.

Phytic acid (PA) reduces nutrient digestibility in pigs and poultry, and has been shown to increase endogenous nutrient losses (ENL) in poultry. However, there is lack of information on the effect of PA on ENL in pigs, and mechanisms by which PA increases ENL. Three experiments were conducted to determine the effects of PA on ENL in pigs and to establish mechanisms by which PA increases the ENL. The first experiment investigated the effect of PA on ileal digestibility and ileal endogenous nutrient flows. Phytic acid decreased the apparent ileal sodium digestibility to a negative value (-18%). The second experiment investigated the effect of PA on gut enzyme activities, histomorphology and sodium-dependent glucose transporter 1 (SGLT1) gene expression. Phytic acid did not affect the gut villous height, villous height to crypt depth ratio, and jejunal SGLT1 gene expression, but decreased gastric pepsin activity and tended to decrease jejunal Na-K-ATPase activity. In the third experiment, the effect of PA on piglet performance and ion uptake in jejunum mounted in Ussing chamber, and jejunal SGLT1 protein level was evaluated. Phytic acid did not affect jejunal SGLT1 protein expression, but lowered piglet performance and jejunal active ion uptake. In conclusion, results from this study show that PA can reduce the apparent ileal digestibility of sodium to a negative value, indicating that PA can increase ileal endogenous sodium loss. The results also show that PA can reduce the pepsin activity and ion uptake in the gut. The reduced pepsin activity implies increased secretion of the enzyme plus hydrochloric acid and hence increased secretion of sodium bicarbonate that neutralizes the acid. The reduced ion uptake by PA implies reduced nutrient absorption. Because sodium is absorbed partly by co-transportation with other nutrients, the reduced ion uptake by PA implies reduced sodium absorption. Thus, it appears that PA increases ileal endogenous sodium flow partly through reduced pepsin activity and ion uptake in the small intestine. Overall, the results show that phytase (a PA-hydrolysing enzyme), which is added in pig diets to improve phosphorus availability, does not only improve phosphorus availability, but alleviates ant-nutritional effects of PA as well.

Phytic acid (PA) reduces nutrient digestibility in pigs and poultry, and has been shown to increase endogenous nutrient losses (ENL) in poultry. However, there is lack of information on the effect of PA on ENL in pigs, and mechanisms by which PA increases ENL. Three experiments were conducted to determine the effects of PA on ENL in pigs and to establish mechanisms by which PA increases the ENL. The first experiment investigated the effect of PA on ileal digestibility and ileal endogenous nutrient flows. Phytic acid decreased the apparent ileal sodium digestibility to a negative value (-18%). The second experiment investigated the effect of PA on gut enzyme activities, histomorphology and sodium-dependent glucose transporter 1 (SGLT1) gene expression. Phytic acid did not affect the gut villous height, villous height to crypt depth ratio, and jejunal SGLT1 gene expression, but decreased gastric pepsin activity and tended to decrease jejunal Na-K-ATPase activity. In the third experiment, the effect of PA on piglet performance and ion uptake in jejunum mounted in Ussing chamber, and jejunal SGLT1 protein level was evaluated. Phytic acid did not affect jejunal SGLT1 protein expression, but lowered piglet performance and jejunal active ion uptake. In conclusion, results from this study show that PA can reduce the apparent ileal digestibility of sodium to a negative value, indicating that PA can increase ileal endogenous sodium loss. The results also show that PA can reduce the pepsin activity and ion uptake in the gut. The reduced pepsin activity implies increased secretion of the enzyme plus hydrochloric acid and hence increased secretion of sodium bicarbonate that neutralizes the acid. The reduced ion uptake by PA implies reduced nutrient absorption. Because sodium is absorbed partly by co-transportation with other nutrients, the reduced ion uptake by PA implies reduced sodium absorption. Thus, it appears that PA increases ileal endogenous sodium flow partly through reduced pepsin activity and ion uptake in the small intestine. Overall, the results show that phytase (a PA-hydrolysing enzyme), which is added in pig diets to improve phosphorus availability, does not only improve phosphorus availability, but alleviates ant-nutritional effects of PA as well.

This study investigates the postlarval development of Penaeus indicus. Particular emphasis is given to characterisation of developmental morphology, growth, ontogenetic change in digestive enzymes, and assessment of energy requirements for postlarval substages. The morphology of the Penaeus indicus postlarvae (PL) changes continuously as consecutive substages (PL1-14) were reached by daily moults. After 22 ecdyses (typically 35 days) the PL22 substage is succeeded by the adult form. Most of the morphological differentiation is observed after 2 weeks at substage PL14, but the branchiae only reach full development from substage PL16. The rostrum teeth, telson spines and ratio of body segments are important characters for identification of Penaeus indicus PL stage. Growth of PL1 postlarvae was significantly slower when fed artificial diets rather than Artemia nauplii. Similarly 14-day postlarvae which were slow developers (PL9) also grew slowly on artificial diets whereas postlarvae of the same age (substage PL14) did not show this suppression. Trypsin and amylase digestive activities increased with PL development (P<0.001) but did not change significantly (P>0.05) with diet fed. Trypsin was low during early PL stages of development and a sharp increase in tryptic activity was only observed at substage PL20 (24 mm). Amylase increased from PL1 and exceeded that of trypsin for 2-3 weeks after metamorphosis. It appears that during early stages of development postlarvae are unable to efficiently digest artificial diets due to low digestive activity. For smaller 14-day postlarvae, poor performance is possible related to a genetic regulated constraint and not to digestive capacity since enzyme levels were similar to those in larger PL14. PL1 fed for 15 days on commercially dried low-hatch decapsulated Artemia cysts showed comparable growth and survival to that of PLs fed on Artemia nauplii, but significantly higher (P<0.05) than that supported by commercial granulated and flake diets and low-hatch decapsulated cysts processed into a granulated diet or dried at 90°C. Leaching of soluble protein and carbohydrates was high for all artificial diets but low-hatch decapsulated cysts were highly stable in water. Commercially dried low-hatch cysts retain a living membrane capable of osmoregulation and retaining highly digestible nutrients important for fast growth and development of postlarvae. Survival of postlarvae was negatively correlated (P<0.05) with leaching of soluble protein, but no correlation was observed for loss of soluble carbohydrates. Daily food ingestion and routine metabolism of postlarvae increased with PL development. Food metabolism (SDA) was low for early PL stages, but increased steadily up to stage PL16 and remained the same from this substage onwards. Assimilation efficiency decreased for early PL substages and remained low up to PL13, and then increased steadily. Different energy strategies seem to be adopted during postlarval development to cope with ontogenetic modifications after metamorphosis. During early development little energy is lost in metabolism, and so more energy is converted to growth to support fast development, with increase in predatory behaviour and development of digestive system. Later more energy is lost in metabolism and committed for maintenance. The ontogenetic changes in digestive activity, energy trend and assimilation efficiency latter in PL development seems to reflect the adaptation to benthic carnivorous existence and migration of postlarvae and juveniles form inshore nursery to deeper waters. Stocking density above 20 PLs 1- reduced growth and survival but increased size variability above the inherent range, for postlarvae PL1-18 days old. However, Penaeus indicus postlarvae showed low agonistic behaviour and tolerated relatively high densities similar to that of other penaeid species, which further enhances the potential and advantages of the white prawn for culture.

Thesis (Ph. D.)--University of Nevada, Reno, 1998. / Includes bibliographical references. Online version available on the World Wide Web.

Ripe fleshy fruits contain an enormous diversity of metabolites that influence ecological interactions with mutualistic and antagonistic species. This dissertation investigates the impact of fruit secondary metabolites on the foraging behavior and digestive physiology of bats (Chapters 2-4) while applying insights from basic chemical ecology to inform forest regeneration strategies (Chapter 5). The studies were conducted in northeastern Costa Rica at La Selva Biological Station. Chapter Two examines the variability and associations between nutrients and secondary metabolites within ripe Piper sancti-felicis fruits, showing that intraindividual variation of chemical traits can surpass interindividual variation and associations between chemical traits are scale-dependent, varying in strength and direction. Chapter Three explores how bats balance nutrient acquisition with defensive metabolite avoidance and the impact of metabolite consumption on bat nutrient absorption. It reveals that nutrient composition is the primary driver of bat foraging behavior and that defensive metabolites can interfere with protein absorption. Chapter Four further uses untargeted metabolomics to explore the influence of secondary metabolites on nutrient absorption, demonstrating that four commercial secondary metabolites induce dose-dependent changes in bat fecal metabolome, altering essential nutrient absorption. Chapter Five translates principles of chemical ecology into practical use by demonstrating the effectiveness of synthetic volatiles in attracting fruit bats and increasing seed rain. Taken together, this dissertation shows the impact of defensive metabolites on a key seed disperser while demonstrating the potential application of chemical ecology to address forest regeneration challenges. / Doctor of Philosophy / Fleshy fruits exhibit a remarkable chemical complexity. Fruit pulp is not only rich in essential nutrients (sugars, proteins, and lipids) but also contains a diverse array of other chemicals collectively known as secondary metabolites. These metabolites shape ecological interactions between fruits and frugivores. This dissertation focuses on understanding the ecological and physiological effects of fruit chemistry on frugivores. The studies were conducted at La Selva Biological Station in northeastern Costa Rica, focusing on fruit bats and pepper plants. Chapter two examines the relationships and variation between nutrients and toxins within ripe fruits of pepper plants (Piper sancti-felicis), finding that the chemical variation within a single plant can exceed the differences between separate plants. Also, depending on the scale studied, toxins and nutrients can be positively or negatively associated. Chapters Three and Four describe the preferences of a fruit bat (Carollia perspicillata) for nutrients and toxins, showing that nutrients are the primary driving force behind food choices and demonstrating that certain fruit toxins alter the ability of bats to absorb nutrients, including different sugars, proteins, and lipids. Chapter Five demonstrates the potential of synthetic chemical lures to attract fruit bats and enhance seed dispersal, offering a promising strategy to promote forest regeneration in degraded areas. Overall, this research demonstrates how fruit chemicals can significantly impact fruit bats, which play a crucial role in dispersing seeds and maintaining forest diversity.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-06-20T18:26:16Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE _DFBC_.pdf: 1525509 bytes, checksum: 91079bb98aed005cbb284a2ec816c4c1 (MD5) / Made available in DSpace on 2016-06-20T18:26:16Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE _DFBC_.pdf: 1525509 bytes, checksum: 91079bb98aed005cbb284a2ec816c4c1 (MD5) Previous issue date: 2016-02-02 / Capes / Este trabalho teve o objetivo de avaliar a influência entre macronutrientes energéticos, com o desempenho, metabolismo e fisiologia digestiva de diferentes surubim híbridos (Pseudoplatystoma corruscans x Pseudoplatystoma fasciatum e Pseudoplatysma fasciatum x Leiarius marmoratus). Esses surubim híbridos são amplamente cultivados no Brasil, para abate sendo a carne destinada ao mercado interno e externo. No entanto, são poucos os dados na literatura em relação às exigências nutricionais para esses peixes, bem como o efeito da relação entre os macronutrientes com a fisiologia digestiva e metabolismo. Deste modo, o capítulo um avaliou o efeito da manga de uma fonte de carboidrato não amiláceo. Para tal foram fornecidas dietas contendo farinha de manga em substituição ao milho em quatro níveis diferentes (0; 33%; 66% e 100%) para alevinos de Pseudoplatystoma sp. Após o período de 60 dias para a análise de desempenho, foram realizadas as atividades das enzimas digestivas: protease total alcalina, tripsina e amilase. Como indicativos de mudança no metabolismo foram avaliados no plasma: triglicérides, glicose, proteínas totais, colesterol, amino ácidos livres; no fígado: glicogênio e alanina aminotransferase. Foi observado que não houve diferença significativa nos parâmetros de desempenho analisados. Entretanto foram observadas alterações nas atividades das enzimas digestivas e intermediários metabólicos, provavelmente devido à quantidade de fatores antinutricionais encontrados na casca da manga. Estes resultados demonstram que em longo prazo a inclusão de farinha de manga acarretará decréscimo no desempenho dos animais. No capítulo dois foi avaliado o efeito de diferentes valores da relação proteína(P):lipídio(L). Quatro dietas (45P 5L; 42P 9L; 39P 11L; 34P 19L%) foram fornecidas por 60 dias para observar o efeito sobre o desempenho, enzimas digestivas, intermediários metabólicos e parâmetros hematimétricos de alevinos do surubim híbrido Pseudoplatysma fasciatum x Leiarius marmoratus. O excesso de lipídio na dieta diminuiu o desempenho o que consequentemente afetou os demais parâmetros avaliados. Valores de proteínas totais e aminoácidos livres no plasma demostraram danos causados pela deficiência de proteína na dieta. Os valores de colesterol, triglicérides e glicose mostraram resposta consequente da baixa ingestão de nutrientes. A lipase foi a enzima digestiva mais influenciada pelos nutrientes dietéticos. Os parâmetros hematimétricos foram afetados pelas dietas e demonstraram que animais que ingeriram maior quantidade de lipídio tiveram adaptação metabólica e fisiológica para suprir a deficiência nutricional. No capítulo três foi avaliado o efeito de diferentes valores da relação proteína(P):carboidrato(C). Quatro dietas (28P 53C; 36P 44C; 40P 39C; 45P 37C%) foram fornecidas por 60 dias para observar o efeito sobre o desempenho, composição corporal, enzimas digestivas e intermediários metabólicos de alevinos do surubim híbrido Pseudoplatysma fasciatum x Leiarius marmoratus. O excesso de carboidrato na dieta diminuiu o desempenho, sem afetar demasiadamente os parâmetros fisiológicos e metabólicos avaliados, mostrando grande adaptação do híbrido avaliado. A eficiência energética das dietas avaliadas foi maior no tratamento com menor inclusão de carboidrato e maior inclusão proteica. Valores de atividades enzimáticas específicas foram maiores no tratamento com maior inclusão de proteína. A maior reserva de glicogênio hepático também foi observado no mesmo tratamento citado acima. Como conclusão geral pode-se afirmar que diferentes relações proteína:energia, independente de ser fonte lipídica ou de carboidrato, afeta o desempenho, fisiologia digestiva e metabolismo do surubim híbrido. / This study aimed to evaluate the influence of macronutrients energetic, growth, metabolism and digestive physiology of different surubim hybrids (Pseuduplatystoma corruscans x Pseudoplatystoma fasciatum and Pseudoplatysma fasciatum x Leiarius marmoratus). These hybrids are highly raised in Brazil with its main products being sold to domestic and international market. However there is few information on literature published about data on nutrient requirements to this fish, as well as the effects among macronutrients and digestive physiology and metabolism. Thus, chapter one evaluated the effect of mango meal as a non-starch carbohydrate source. In order to accomplish it, diets containing mango meal replacing corn meal in four different levels (0; 33%; 66%; 100%) were given to Pseudoplatystoma sp. juvenile. After 60 days growth analysis were done as well as the digestive enzymes activities: total alkaline protease, trypsin and amylase. As indicative of metabolism changes were evaluated in the blood plasma: triglycerides, glucose, total proteins, cholesterol, free amino acids; in the liver: glycogen and alanine aminotransferase. It was observed no significant difference among growth parameters evaluated. However digestive enzymes activities and intermediary metabolic changes were observed, probably due to anti-nutritional factors found in mango skin. These results shows that, in long term feeding mango meal inclusion can lead to animal growth decrease. In chapter two it was evaluated the effect of different protein(P):lipid(L) ratios. Four diets (45P 5L; 42P 9L; 39P 11L; 34P 19L) were offered for 60 days to observe the effect on growth performance, digestive enzymes activities, intermediary metabolism and hematimetric parameters of hybrid surubim Pseudoplatysma fasciatum x Leiarius marmoratus juvenile. Dietary lipid excess decreased growth which consequently affected the others parameters evaluated. Plasma total protein and free amino acids values demonstrated injuries caused by protein deficiency in the diet. Cholesterol, triglycerides and glucose values showed consequent response to low nutrient ingestion. Lipase was the enzyme more influenced by dietary nutrients. Hematimetric parameters were affected by diets and showed that animals that ingested higher lipid amount had metabolic and physiologic adaptation to make up nutritional deficiency. In chapter three it was evaluated the effect of different protein(P):carbohydrate (C)values. Four diets (28C 53C; 36P 44C; 40P 39C; 45P 37C) were offered for 60 days in order to observe the effect on growth, whole body composition, digestive enzymes and intermediary metabolism of hybrid surubim Pseudoplatysma fasciatum x Leiarius marmoratus juvenile. Dietary carbohydrate in excess decreased growth without affecting all of others physiological and metabolic parameters evaluated, which shows high adaptation. Feed energetic efficiency evaluated was higher in the treatment with lower carbohydrate inclusion and higher protein inclusion. Specific digestive enzymes activities were higher in the treatment with higher protein inclusion. Higher hepatic glycogen reserve was also observed in the same treatment cited above. As a general conclusion it can be affirmed that different protein:energy ratio, no matter if it is lipidic or carbohydrate source, affects growth, digestive physiology and metabolism of hybrid surubim.

<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>

Les attentes sociétales s’orientent vers une consommation saine, et provenant de systèmes agricoles durables. En filière cunicole, la maîtrise des pathologies digestives nécessite le recours à l'antibiothérapie curative ou préventive. La recherche d’alternatives à l’utilisation d’antibiotiques en élevages cunicoles est donc primordiale pour augmenter la durabilité de cette production. Les stratégies de limitation de la quantité d’aliment ingérée sont une des solutions possibles à ce problème, puisqu'elles améliorent la résistance du jeune lapin aux troubles digestifs. Ce travail de thèse a pour objectif d’étudier les mécanismes sous-jacents à cet effet favorable des stratégies de rationnement, et aussi d'analyser le comportement alimentaire du lapin restreint en relation avec son bien-être. Cet objectif se scinde en deux parties étudiées. La première partie a pour but de déterminer quelle caractéristique de la restriction alimentaire limite les troubles digestifs en engraissement. La seconde partie s’intéresse aux paramètres biologiques potentiellement influencés par cette stratégie d’alimentation. Les paramètres considérés sont reliés à plusieurs domaines de biologie : enzymologie, histométrie, écosystème bactérien cæcal. Une restriction de l'ingéré de -25% réduit la croissance mais améliore significativement l’efficacité digestive (de 4 à 6% entre 28 et environ 50 jours d'âge) des lapins en engraissement, qui peut s'expliquer par une plus forte digestibilité des fractions protéique (4,5%), énergétique (5,3%) et fibreuses (NDF : 8,9%, ADF : 9,7%, hémicelluloses: 7,9%, cellulose : 11,5%). Cependant, la structure, la diversité et la densité de la communauté bactérienne cæcale sont peu modifiées chez l'animal restreint sain. Des modifications du comportement alimentaire ont été soulignées au cours de ce travail. Ainsi, le rythme d’ingestion, fonction du rythme nycthéméral pour les lapins nourris à volonté, est dépendant du moment de distribution de l’aliment pour les animaux restreints. Après 18 jours de restriction, les lapins ingèrent un tiers de la quantité qui leur est distribuée en 2 heures, et la totalité en moins de 10 heures. Mais aucune agressivité ou compétition n’a été observée entre les animaux restreints. Plusieurs pistes peuvent expliquer l’efficacité de cette stratégie d’alimentation sur la santé digestive du lapereau. Ainsi, les résultats obtenus au cours de la reproduction d’une colibacillose (Escherichia coli O128:C6) suggèrent une stabilisation de l’écosystème iléal par la restriction alimentaire après l’infection. D'autre part, au niveau cæcal l'activité des communautés bactériennes serait modulée, même si pour ce modèle, l'effet d'une ingestion limitée semble faible sur le statut sanitaire. Enfin, l’alternance de périodes de satiété et de périodes de faim stimule la libération sanguine d’hormones (ghréline notamment) qui pourraient moduler la fonction immunitaire. En perspectives, il serait pertinent d'étudier plus précisément les fonctions liées au statut immunitaire ou endocrinologique. De plus, l'étude plus approfondie de la communauté bactérienne cæcale, en ciblant certaines espèces, pourrait apporter un complément d’informations sur les interactions entre ingestion et symbiote digestif et lors d'une approche comparée de 2 modèles pathogèniques : EPEC vs. EEL. / Societal expectations are moving towards healthy food from sustainable farming systems. In rabbit industry, control of digestive diseases requires the use of curative or preventive antibiotics. The search for alternatives to the use of antibiotics in rabbit breeding is thus crucial to improve sustainability of this production. Strategies for limiting the amount of feed ingested are one possible solution to this problem, since they improve the digestive resistance of young rabbits. This thesis aims to study the mechanisms underlying this positive effect of restriction strategies, and also to analyze the feeding behaviour of restricted rabbit in relation to their welfare. This objective is divided into two parts. The first part aims to determine which characteristic of feeding restriction limits the digestive disorders in fattening. The second part deals with the biological parameters potentially influenced by this feeding strategy. The parameters considered are related to several areas of biology: enzymology, histometry, digestive bacterial ecosystem A reduction of feed intake of -25% reduced growth, but significantly improved digestive efficiency (4 to 6% between 28 and 50 days old) of fattening rabbits which can be explained by a higher protein digestibility (4.5%), energy (5.3%) and fibres (NDF: 8.9%, ADF: 9.7%, hemicellulose 7.9%, cellulose: 11.5%). However, the structure, diversity and density of the caecal bacterial community are little changed in the healthy animal fed restricted. Changes in eating behaviour were highlighted during this work. Thus, the rhythm of intake, depending on the circadian rhythm in rabbits fed ad libitum, is function of the feed distribution time for restricted animals. After 18 days of restriction, rabbits ingest in 2 hours the third of the quantity supplied, and the entire amount within 10 hours. No aggression or competition was observed between animals. Several hypotheses could explain the effectiveness of this strategy on digestive health in young rabbit. Thus, the results obtained during the reproduction of colibacillosis (Escherichia coli O128: C6) suggest a stabilization of the ileal ecosystem after infection. On the other hand, the main activity of bacterial communities of caecum would be modulated, even if for this model a limited intake moderately modified the sanitary status. Finally, the alternation of periods of satiety and hunger may stimulate the release of hormones (e.g. ghrelin) that could modulate immune function. In perspective, it would be appropriate to study more precisely the functions related to immune or endocrine status.In addition, a deeper study of the caecal bacterial community by targeting some species could provide additional informations on the interactions between intake and digestive symbiote, and on a comparative approach of the two pathogenic models: EPEC vs. REE.

L'aquaculture est en pleine expansion et fournit aujourd'hui la moitié des produits aquatiques destinés à la consommationhumaine. Elle constitue ainsi un secteur clé pour le maintien et l'amélioration de la sécurité alimentaire dans lemonde. Le développement de l'aquaculture est étroitement lié à celui des formules alimentaires. Ces dernières années,la part des farines de poisson dans la formulation des aliments a particulièrement diminué au profit des farines d'originevégétale pour répondre aux nombreuses contraintes économiques et environnementales. Néanmoins, ces matièrespremières sont moins adaptées aux besoins nutritionnels des poissons carnivores et leur utilisation peut entraîner unebaisse des performances de croissance et d'efficacité alimentaire. L'ajout d'additifs et d'ingrédients fonctionnels devientalors indispensable. Les hydrolysats protéiques issus des co-produits de la pêche et de l'aquaculture sont des ingrédientsà fort potentiel appétence, nutritionnel et bioactif. Ces ingrédients sont des mélanges complexes riches en peptides hydrolytiqueset en acides aminés libres, mais dont la composition varie en fonction de l'origine de la matière première etdes paramètres d'hydrolyse appliqués lors de leur fabrication. Au cours de ces travaux de thèse, nous avons développéet mis en pratique des outils permettant d'approfondir la caractérisation structurale et les propriétés fonctionnellesdes hydrolysats de protéines. Dans un premier temps, nous avons développé une méthode analytique basée sur unenormalisation des échantillons suivie d'une détermination de l'abondance et de la richesse en peptides par chromatographied'exclusion stérique et chromatographie liquide couplée à la spectrométrie de masse de type électro-spray,respectivement. Les résultats présentés sous forme d'un diagramme 2D permettant de classer et comparer facilementles hydrolysats de protéines de forme galénique, d'origine et de process différents. Nous avons également développé unoutil in vitro sur l'intestin de bar européen, Dicentrarchus labrax, permettant de déterminer les activités myotropesdes hydrolysats. Nous avons pu notamment démontrer que l'hydrolysat de crevettes possède une plus forte activitémyotrope que les hydrolysats de poissons et que cette activité est portée par un pentapeptide KNPEQ clivé à partirde l'hémocyanine lors du process d'hydrolyse appliqué sur les co-produits de crevette. Enfin, dans un second temps,un conditionnement alimentaire de 65 jours a été conduit chez le bar européen nourri avec un aliment pauvre en farinede poisson supplémenté en hydrolysat de différentes origines et couplé à une analyse d'expression génique (approcheen RNA-Seq Illumina). Cette étude a permis de montrer que les hydrolysats de protéines appliqués sur un alimentfaible en farine de poisson (5%) sont capables de restaurer des performances de croissance équivalentes à celles d'unrégime contenant 20% de farine de poisson mais qu'ils portent par ailleurs des propriétés fonctionnelles spécifiques.Il a également été montré que le mélange des deux hydrolysats permet de moduler les transcriptomes intestinal ethépatique de façon plus profonde que lorsque que les hydrolysats sont utilisés séparément. Ces résultats confirmentl'intérêt des hydrolysats de protéines pour la formulation d'aliment à faible teneur en farines de poisson et apportentde nouveaux outils de caractérisation de ces ingrédients complexes, qui seront utiles pour leur optimisation et leurstandardisation ainsi que pour la compréhension de leurs mécanismes d'action chez les poissons. / Aquaculture is a key sector for supporting and improving the food security worldwide. The global production of farmedfish and shrimp has grown dramatically over the past decades and now contributes to half of the aquatic productsintended for human consumption. Aquaculture will require feeds to support its growth but availability of some raw materialssuch as fish meal are limited. The use of fish meal in aquafeed has particularly declined in favor of plant proteinsources to fit with economic and environmental constraints. But plant proteins do not meet perfectly the nutritionalrequirements of carnivorous fish and their utilization often results in lower growth and feed performances. Proteinhydrolysates manufactured from fishing and aquaculture co-products are ingredients with a high palatable, nutritionaland bioactive potential. They are rich in hydrolytic peptides and free amino acids, but they are complex mixtureswhose composition could vary according to raw material origin and hydrolysis parameters. During this PhD study, wedeveloped and implemented tools to further characterize the structure and functional properties hydrolysates. On afirst step, we developed a fast methodological tool based on sample standardization, followed by the determination ofthe abundance and richness of peptides using size exclusion chromatography and liquid chromatography coupled toelectro-spray mass spectrometry, respectively. We merged the results into a 2D diagram that made it easy to classifyand compare hydrolysates having different galenic, origin and process. We also developed a tool on isolated intestinefrom European seabass (Dicentrarchus labrax ) to rank protein hydrolysates according to their myotropic property.We demonstrated that shrimp hydrolysate showed a higher myotropic activity than fish hydrolysates and that thisactivity was carried by a unique pentapeptide KNPEQ produced by the enzymatic clivage of haemocyanin during thehydrolysis process applied on shrimp co-products. On a second step, a 65-day feeding trial was conducted in Europeanseabass fed a low fish meal diet supplemented with protein hydrolysates of different origin, and coupled to a studyof the intestine and liver transcriptomic response (Illumina RNA sequencing). It has been shown that protein hydrolysatesincluded in a low fish meal diet (5%) restored growth performances to the same level than a diet containing20% of fishmeal, and that they exhibited very specific functional properties. These results showed that a mixture oftwo hydrolysates impacted more deeply the intestine and liver transcriptomes than hydrolysate tested alone. ThisphD study confirmed that protein hydrolysates are very interesting candidates for formulating low fish meal feed andoffer new tools for characterizing such complex ingredients, which will be useful to optimize and standardize proteinhydrolysate while understanding their mechanisms of action in fish.