Dissertations / Theses on the topic 'Weaning'

The response of foals to the stress of weaning was examined in terms of a behavioral protocol and the responses of plasma ascorbate, serun1 cortisol, and the serum cortisol response to an ACTH challenge. Behavior scores (1 to 10) as an index of stress were assigned to each foal daily, with high scores indicating less stress and better adjustment. The experimental plan was a 2 X 2 factorial of pre-weaning diet and stall weaning method. Foals were raised on pasture supplemented with hay and a pelleted concentrate (PHC) or pasture supplemented with hay only (PH). Foals were placed in stalls singly or in pairs for weaning. Gender influences were also examined. The foals exhibited characteristic behavioral and physiological responses to the social dislocative stress of weaning. Behavior scores were lower in paired than in single foals (p = .008) and tended to be lower in PH than PHC foals (p = .15). No differences in post-weaning plasma ascorbate concentrations were found among treatments. Responses of serum cortisol to an ACTH challenge were lower in PH than PHC foals (p = .001) and in paired than single foals (p = .058), and lower responses were taken to represent adrenal depletion arising from stress. Behavior scores were positively correlated with the response of serum cortisol to ACTH. Both behavioral data and the serum cortisol response to ACTH indicate that foals were better able to cope with weaning stress when supplemented with concentrate prior to weaning and when weaned singly.
Master of Science

The objective of this study was to assess the effect of low stress (LS) handling of beef calves on weight gain and calf activity associated with the weaning process. Cattle were of Angus and Angus cross breeding from two separate herds in Virginia. Handlers for the LS groups went through a short training session. Handlers for the Control (C) groups did not have any special training and handled their group as they would have with no adjustments. Handling and calf activity were monitored each time (6 times) the cows were worked from calving through one month post-weaning. Weights were taken from birth to one month post-weaning. During the week post-weaning the C calves averaged a gain of 4.38 lbs. and the LS calves averaged a gain of 16.94 lbs. One month post-weaning the C calves averaged a gain of 49.01 lbs., while the LS calves averaged a gain of 68.6 lbs. This showed a difference (p < 0.0001) between handling method for weight gain in calves for one week and one month post-weaning. Pedometers were used to assess calf activity post-weaning. Steps per hour (SPH) for the week post-weaning was numerically higher for those calves handled conventionally and not trained for weaning. The C calves averaged 1048 to 1629 SPH for the first three days, where the LS calves averaged 443 to 644 SPH for the first three days. Additionally, the artificial insemination conception rates (AICR) were calculated in each herd and treatment groups compared, however results were equivocal. This study demonstrated that handling cattle using low stress techniques can make significant improvements with regard to weaning weights and has potential to increase other areas of production in beef cattle.
Master of Science

Master of Science
Department of Animal Sciences and Industry
Joann M. Kouba
The objectives of these studies were to (1) characterize mare milk and fecal bacteria, and foal fecal microbiota from birth to 4 mo and (2) determine the effect of weaning and weaning method on foal fecal bacterial composition. Next generation sequencing of the V4 region of the bacterial 16S rRNA gene was performed using the Illumina Miseq according to Earth Microbiome Project protocols and sequencing data was analyzed using QIIME. In experiment 1, mare milk, mare fecal, and foal fecal samples were collected from 9 mare and foal pairs at birth (d 0), d 2, 7, and 1, 2, 3 and 4 mo. In experiment 2, 9 foals were separated into 2 treatments: abrupt (n = 5) and gradual (n = 4) weaning methods. Fecal samples were collected the day before weaning (d-1), the day of weaning (d 0) and post-weaning on d 1, 2, 3, 4, and 7. Blood was collected for analysis of cortisol concentration at 0800 h on d -1, 1, 2, and at 0800 h and 1100 h on d 0 and 4. Heart rate was recorded in 10 min intervals on the day of weaning starting 1 h before weaning to 2 h post-weaning, and again for 1 h starting 24 h after weaning. Results from experiment 1 showed newborn foal meconium and mare milk were similar in species diversity and composition; however, large shifts in composition and increases in foal fecal bacterial diversity occurred within the first week. By 1 mo, foal fecal bacterial composition did not differ in composition from mare feces at the phylum level (P = 1.0). Firmicutes, Bacteriodetes, Verrucomicrobia, and Spirochaetes were the dominant phyla found in feces of foals 1 mo and older and adult mare feces. For experiment 2, there were no differences in species diversity (P > 0.05) or separations in bacterial community structure between weaning methods or before and after weaning. There were minor shifts in relative abundance of specific phyla and genera in response to weaning. Foals in the abrupt treatment group had increased cortisol concentrations on d 1 (P < 0.05) and increased heart rate for 50 min after weaning on d 0 (P < 0.05). The foal is born with fecal microbial communities similar to milk that rapidly change during the first week of life, reaching the same composition of its dam by the first month. The foal fecal microbiota matures prior to weaning, therefore weaning did not cause drastic changes in bacterial composition. Although acute stress was increased in abruptly weaned foals, stress associated with different weaning methods did not influence the fecal microbiota within the first week post-weaning.

My research identifies an emerging trend among writers working on the borders of fiction and non-fiction for novels that function as aesthetic autobiographies. These works articulate ways in which the lived experience of the writer intersects with the artistic expression of these experiences. I examine novels by Rachel Cusk, Elena Ferrante, Sheila Heti, Jhumpa Lahiri and Deborah Levy as well as non-fiction texts by these authors. I argue that works by these women writers form a conversation of the kind Helene Cixous urges in her essay 'The Laugh of the Medusa' and I view the resulting work as a female countercanon. Further, I argue that these works constitute a canon of motherhood, to which my own novel The Weaning might belong. As a way of furthering my understanding of my own creative practice I consider the exchange that occurs between writer and proxy, writer and text, writer and reader, reader and text as a process of literary weaning.

Conventional techniques within the beef cattle industry involve weaning the calf from the dam when the calf is about 205 days of age. Weaning induces a stress-response that is implicated in reducing the health and productivity of newly weaned calves. Our goal was to evaluate the impact of weaning on the stress immune responses of beef calves. To that end, we 1) evaluated novel methods to quantify physiological markers of stress, 2) compared immune function and growth of calves grazing legume versus grass forages, and 3) compared the effects of abrupt versus two-stage weaning on calves. In study 1, calf, yearling, and adult beef cattle were used to assess the accuracy and precision of handheld glucometers in quantifying bovine blood glucose concentration. Precision Xtra® and ReliOn® glucometers were used chute side to quantify blood glucose concentrations in cattle and were compared to an accepted plasma glucose analysis on the same samples for validation. The Precision Xtra® glucometer was more accurate and precise than the ReliOn® glucometer. In study 2, weaned heifers were used to compare the immunomodulatory effects of grazing alfalfa versus fescue over a 30 day grazing period. No differences were detected in the interferon gamma (IFNγ) production and weight gain between the heifers on alfalfa and fescue. In study 3, effects of two-stage (fenceline) and abrupt weaning were compared. Calf weights, immune cell function, antibody production, blood glucose concentrations, fecal cortisol concentrations, and gene expression (FAS, IL-4,IL-10, and IFNγ) were measured pre- and post-weaning. On the day after weaning, the abruptly weaned calves had higher blood glucose concentrations than fenceline weaned calves. Fecal cortisol concentration and gene expression of FAS and IL-4 increased in both groups after weaning, but no differences were detected between the weaning treatments. Gene expression of IL-10 and IFNγ did not change over time. No date, treatment or treatment*date effect was detected for total weight gain or IFNγ production within the non-stimulated and the mitogen-stimulated whole blood samples.
Master of Science

Background. A significant gap in prior research in the area of mechanical ventilation (MV) weaning is the paucity of studies that have investigated the adverse psychophysiological impact of a failed weaning trial, as well as relationships that may exist among psychological and physiological factors on weaning outcomes.Purpose. The purpose of this study is to test the psychophysiological ventilator weaning model (PVWM), which is theory based and empirically derived, to explain the repeated ventilator weaning failure. Methods. This was a cross-sectional design study. A convenience sample (N = 102) of mechanically ventilated patients who had failed their first weaning trial were enrolled in the study. The data collection was a prospective design. Confirmatory factor analysis (CFA) and structure equation modeling (SEM) were used to test the goodness of fit of PVWM and hypotheses of this study. Results. The results indicated that the originally specified measurement model was a misfit with the sample data. Accordingly, a modified measurement model was established by dropping four indicators for further structural model and hypothesis testing. Conditioned fear strongly affected state anxiety, but had no significant effects on respiratory function and weaning outcome. State anxiety presented non-significant effects on respiratory function and weaning outcome. Among the three psychophysiological factors in PVWM, respiratory function had the strongest effect on the length of MV. Based on the underpinning theoretical thinking, the alternative models were established by post hoc analysis and were confirmed by nested model comparison.Conclusion. The resulting model indicates that patients who have a high acquired conditioned fear from the first ventilator weaning failure will have a high state anxiety during the second weaning trial. High state anxiety will cause compromised respiratory function during the weaning process and further cause prolonged mechanical ventilation in the subsequent weaning. The outcomes in the subsequent weaning trial will also be directly determined by MV patients' state anxiety and respiratory function. Findings from the present study provide a different perspective, new insight, and a direction for health care providers to consider when managing the care of patients with repeated ventilator weaning failure.

Introduction: Weaning from mechanical ventilation is defined as the gradual reduction of mechanical support, and replacing this support with spontaneous ventilation. It is a complex process involving assessing the patient's readiness to wean, optimising factors that can impede the process, selecting the most appropriate weaning mode and continually assessing the patient's progress. In paediatric intensive care the clinician must also account for the unique physiological and psychosocial needs of the child. Aim: The aim of the study was to explore the need for, and impact, of guidelines for weaning children from mechanical ventilation on patient outcomes and staff practice. Method: The study was multi-dimensional using the Model for Improvement as the conceptual framework and decided into four phases. Phase one: A survey of Australian PICUs in 2000 revealed that over 2500 children were ventilated over a 12 month-period, with a potential population of 625 children experiencing difficulties with weaning from mechanical ventilation. No guidelines for weaning children from mechanical ventilation were identified at the time. Standardising the approach to weaning had proven successful with the adult population. Phase two: Collaborative guidelines for weaning, based on available evidence and expert opinion, were drawn up, validated by a panel of experts and safely piloted. Phase three: The guidelines were then tested using a time series design over two years on a PICU at a tertiary referral children's facility. Results demonstrated that total ventilation time, weaning duration and length of stay were not significantly improved in the experimental group. However, quality indicators were slightly improved and a survival analysis also showed a slightly reduced probability of long term ventilated patients remaining ventilated. Results also demonstrated a reduction in the fluctuation of outcome variables over time indicating improved consistency in weaning due to the guidelines Phase four: A qualitative analysis of focus group interviews with staff about the impact of guidelines on their practice generated themes, centred on practice development, framework, relationships and challenges. Few previous studies have investigated the perceptions of staff regarding use of practice guidelines. This study identified that staff viewed the use of weaning guidelines favourably and perceived that their implementation improved patient outcomes. Weaning is a relatively neglected area of intensive care because much of the initial focus of management is resuscitation and stabilisation. This study has demonstrated the positive impact that standardised and collaborative practice can have on patient outcome and clinical practice.

Introduction: Weaning from mechanical ventilation is defined as the gradual reduction of mechanical support, and replacing this support with spontaneous ventilation. It is a complex process involving assessing the patient's readiness to wean, optimising factors that can impede the process, selecting the most appropriate weaning mode and continually assessing the patient's progress. In paediatric intensive care the clinician must also account for the unique physiological and psychosocial needs of the child. Aim: The aim of the study was to explore the need for, and impact, of guidelines for weaning children from mechanical ventilation on patient outcomes and staff practice. Method: The study was multi-dimensional using the Model for Improvement as the conceptual framework and decided into four phases. Phase one: A survey of Australian PICUs in 2000 revealed that over 2500 children were ventilated over a 12 month-period, with a potential population of 625 children experiencing difficulties with weaning from mechanical ventilation. No guidelines for weaning children from mechanical ventilation were identified at the time. Standardising the approach to weaning had proven successful with the adult population. Phase two: Collaborative guidelines for weaning, based on available evidence and expert opinion, were drawn up, validated by a panel of experts and safely piloted. Phase three: The guidelines were then tested using a time series design over two years on a PICU at a tertiary referral children's facility. Results demonstrated that total ventilation time, weaning duration and length of stay were not significantly improved in the experimental group. However, quality indicators were slightly improved and a survival analysis also showed a slightly reduced probability of long term ventilated patients remaining ventilated. Results also demonstrated a reduction in the fluctuation of outcome variables over time indicating improved consistency in weaning due to the guidelines Phase four: A qualitative analysis of focus group interviews with staff about the impact of guidelines on their practice generated themes, centred on practice development, framework, relationships and challenges. Few previous studies have investigated the perceptions of staff regarding use of practice guidelines. This study identified that staff viewed the use of weaning guidelines favourably and perceived that their implementation improved patient outcomes. Weaning is a relatively neglected area of intensive care because much of the initial focus of management is resuscitation and stabilisation. This study has demonstrated the positive impact that standardised and collaborative practice can have on patient outcome and clinical practice.

Vitamin E deficiency syndromes are still reported in post-weaning pigs despite dietary supplementat ion with the vitamin being apparently adequate. In view of this situation. the studies presented in this thesis have been conducted to determine the requirement of this vitamin for post-weaning pigs. In the initial study (Chapter 4), post-weaning pigs were fed a diet based on corn starch and soyabean meal supplemented with 0, 20 and 100mg dl- a-tocopheryl acetate/kg respectively. Results showed that vitamin E concentrations in plasma and tissues reflected dietary levels of vitamin E. Although no apparent clinical signs of vitamin E deficiency were observed. pigs on the diet withOut vitamin E supplementat ion had significantly higher (P<0.05) lipid peroxidation levels (indicated by thiobarbituric acid reaction values of red blood cells and ethane and pentane levels in exhaled gases) than those fed diets supplemente d with 20mg or 100mg vitamin E/kg. The elevation of lipid peroxidation levels in pigs fed the unsupplemen ted diet provided biological evidence that these pigs were deficient in vitamin E. The lipid peroxidation level decreased with an increase of dietary vitamin E supplementation. but supplementation at 20mg or 100mg/kg provided equivalent protection for pigs. This suggests that dietary supplementat ion with 20mg dl—a-tocopher yl acetate/kg is adequate for post-weaning pigs when the diet contains low levels of fat and adequate selenium. The lipid peroxidation response of pigs to dietary vitamin E supplementat ion indicates that lipid peroxidation status is an accurate index and more sensitive measurement than plasma and tissue concentrations of the vitamin for evaluation of the requirement of vitamin E for pigs. Moreover. studies indicate that the production performance of the pigs was not influenced by dietary supplementation with vitamin E. When different levels and types of fat were added to diets. it was found that vitamin E levels, as well as lipid peroxidation status of pigs. were affected by dietary fat (Chapters 5 and 6). For the pigs fed diets supplemented with 50mg vitamin E/kg. dietary supplementat ion with sunflower oil at 10% resulted in significantly decreased vitamin E concentrations in plasma and tissues compared to those on the diet supplemente d with 1% oil (P<0.05). Pigs fed the diet supplemen ted with 10% tallow also had higher vitamin E concentrations in plasma and tissues than those on 10% sunflower oil diet. but the difference was only significant (P<0.05) in adipose tissue. For the pigs fed vitamin E unsupplemented diets. lipid peroxidation values increased as the dietary oil levels increased (P<0.05). When pigs were fed diets supplemented with different levels of soyabean oil and 11mg vitamin E/kg (Chapter 6), lipid peroxidation values were positively correlated (P<0.05) with the dietary level of oil. The effect of dietary fat on vitamin E and lipid peroxidation status of pigs indicates that vitamin E requirements for post-weaning pigs are afl'ected by levels and types of dietary fat. The NRC (1988) recommended level of vitamin E requirements for post-weaning pigs (1 l - 16mg/kg diet) is inadequate when levels of dietary oil exceed 5%. Although dietary y—tocopherol concentrations were higher or equal to that of atocopherol (derived from dl-a-tocopheryl acetate). the concentrations of the former in plasma and tissue were much lower than that of a-tocopherol (Chapters 6 and 7). The biological activity of y-tocopherol for post-weaning pigs was less than 20% of atocopherol. a-Tocopherol concentrations in plasma and tissues increased as y—tocopherol intakes increased. indicating that the presence of y—tocopherol in the diet spared atocopherol. Studies of the gastro-intestina l absorption of vitamin E demonstrated that the absorption of vitamin E in pigs was incomplete, about 50 to 60% of dietary vitamin E being absorbed (Chapter 8). The absorption efficiency was not influenced by the source or amount of dietary fat. Absorption was similar for both a- and y-tocopherols. The results of the absorption studies indicate that the decrease in vitamin E levels of pigs with an increase of dietary oil intake was not due to decreased absorption of vitamin E. but due to enhanced post-absorptive utilization of the vitamin.

Dissertação de Mestrado em Medicina Veterinária
O desmame é uma das etapas mais complexas na produção suinícola e com mais influência nos resultados finais, sendo relevante confrontar as diferentes opções de maneio nesta fase e o seu impacto no desempenho produtivo dos suínos. Durante o período de seis meses acompanhou-se numa exploração o desmame de 13 grupos de leitões com idade próxima de quatro semanas e o desmame de um grupo com idade próxima das três semanas, totalizando 5874 leitões. Observaram-se ainda alguns desmames parciais que ocorreram em simultâneo. Os leitões foram reagrupados por tamanhos e a sua adaptação ao pós-desmame foi analisada recorrendo à observação visual de diferentes parâmetros: tamanho, aspeto, vivacidade, apetência, estado hígido e comportamentos associados ao stress. Os leitões maiores e mais velhos demonstraram mais comportamentos agressivos mas uma melhor evolução no pós-desmame e uma maior facilidade de adaptação. Os leitões mais jovens exibiram mais comportamentos associados ao stress, mais problemas sanitários indicadores de uma menor capacidade imunitária, menor ingestão de alimento e, em geral, maior dificuldade de adaptação ao pós-desmame. O recurso a desmames faseados proporcionou resultados que ficaram aquém das vantagens descritas na literatura. Foi possível concluir que, mesmo perante condições confortáveis de pós-desmame, há vantagem no desmame às quatro semanas em relação ao desmame às três semanas, com reflexos evidentes no crescimento dos leitões.
ABSTRACT - Weaning is one of the most complex moments in pig production, having the highest impact on the final production results, becoming relevant to evaluate the different weaning options and its impact on pig’s performance. During a six months period on a pig farm, the weaning of 13 groups of piglets at near four weeks of age and one other group around three weeks was followed, on the total of 5874 piglets. Some partial weanings that occurred simultaneously were also observed. The piglets were regrouped by sizes and their postweaning adaptation was assessed through visual observation of size, appearance, vigor, appetite, health status and behaviors associated with stress. The biggest and oldest piglets showed a more aggressive behavior, but also a better postweaning performance and an easier adaptation to the new environment. The smallest and youngest piglets exhibited more behaviors associated with stress, more health problems indicating a less immune maturity, lower intake and, in general, a more difficult adaptation to postweaning. Results of partial weanings were below those described in the literature. It was possible to conclude that, even with confortable postweaning conditions, the four weeks old weaning showed better results than the three weeks old weaning, with clear reflexes on the piglets growth.

En el presente trabajo se estudian diferentes estrategias de aprendizaje de la conducta alimentaria en cerdos lactantes y destetados. Los lechones podrían aprender a preferir aromas a través de su madre (Capitulo 1 y 5), por ensayo y error (Capitulo 2 y 3) o mediante interacciones sociales con otros lechones (Capitulo 4). Este aprendizaje podría mejorar la ingesta de nuevos piensos que suelen provocar neofobia. El capitulo 1 evalúa si lechones lactantes pueden reconocer y preferir claves aromáticas del liquido amniótico. Los animales fueron expuestos a un test de preferencia entre líquido amniótico materno, líquido amniótico control y agua. Otros animales escogieron entre un aroma previamente añadido a la dieta de gestación de la cerda, un aroma control y agua. Finalmente se evaluaron las preferencias por un pienso con o sin los productos aromáticos previamente añadidos al pienso de la cerda gestante. Los lechones mostraron preferencias frente al líquido amniótico de su propia madre como también frente a los aromas previamente dados a las dietas de las cerdas. Sin embargo, el contacto prenatal con estos aromas no fue suficiente para crear preferencias por el pienso que contenía el aroma. El capitulo 2 estudia el aprendizaje por ensayo y error. Los cerdos fueron entrenados a beber (30 minutos) un aroma (CS+) mezclado en una solución proteica (Concentrado proteico de soja o Péptidos Digestibles Porcinos; PDP) y otro aroma (CS-) mezclado en agua durante sesiones alternadas (6d). Los cerdos mostraron preferencias por CS+ sobre CS- en todos los test realizados. En un segundo experimento un aroma previamente condicionado fue capaz de aumentar la atracción por PDP cuando el aroma y la proteína fueron puestos juntos en la misma solución demostrando sinergia entre la preferencia por CS+ y la preferencia innata de la proteína. El capitulo 3 evalúa preferencias por aromas condicionadas a través del efecto post-ingestivo de nutrientes. Los cerdos fueron entrenados durante 8 días con un aroma (CS+) en soluciones proteicas (4%PDP) o sucrosa (4%) y con otro aroma (CS-) en soluciones con glutamato monosódico (100 mM) o sucrosa (1%) + sacarina (0.08%). Los cerdos mostraron mayores consumos de CS+ sobre CS- debido al aprendizaje asociativo entre los aromas y consecuencias post-ingestivas. El Capitulo 4 describe el aprendizaje social de conductas alimentarias en cerdos destetados. Tras diferentes experimentos, los animales mostraron preferencias marcadas por un pienso aromatizado tras interacciones sociales (30 min) con animales que habían consumido previamente el mismo pienso. Sin embargo, estas preferencias solo se visualizaron si ambos animales (el observador y demostrador) eran familiares. El capitulo 5 estudia la importancia de lácteos en las dietas post-destete y la posible influencia de una exposición pre y post-natal de PDP a través del pienso materno en el rendimiento productivo de lechones en transición. Los resultados no muestran diferencias entre lechones alimentados con dietas con productos lácteos (suero de leche 14%) o con dietas sin estos productos y PDP (2%). Sin embargo, los animales mostraron una mayor preferencia y aceptación por la dieta que tenía lácteos (Test de preferencia y de aceptación de 30 minutos). Cuando se utilizo la estrategia de añadir el PDP a las dietas de la cerda, los animales mostraron una tendencia a presentar mayores ganancias y consumos que cerdos control (15-33d post-destete). Como conclusión se puede decir que los cerdos son capaces de preferir claves aromáticas a través del aprendizaje asociativo previo de estas claves con las consecuencias positivas del líquido amniótico, nutrientes y contacto social. Esto podría incrementar las opciones que los cerdos tienen de adaptarse frente a nuevas claves sensoriales en un pienso.
The present work studies different learning strategies to increase the preference for flavours cues during lactation and after weaning. We propose that pigs may learn flavour preferences from their mother (Chapter 1 and 5), from trial and error tasks (Chapter 2 and 3) or from social interactions with conspecifics (Chapter 4), and that this learning may improve intake of new diets. Chapter 1 evaluate if piglets have the ability to prefer cues of maternal amniotic fluid after birth. During 7 minutes piglets couples were tested to prefer between maternal amniotic fluid, alien amniotic fluid and water or between a flavour added into late gestation maternal diet, a control flavour and water. The same prenatal strategy was used to study piglet’s preferences for flavoured or unflavoured creep feed during the suckling period. Suckling piglets preferred the amniotic fluid from their own mother over an alien amniotic fluid and also they preferred flavours cues given to the sows during the gestation period. However, prenatal flavour exposure did not created feed preferences during lactation. Chapter 2 study if piglets could learn by trial and error to prefer a new flavour cue. Animals were trained to drink (30min/day) one flavour (CS+) mixed into 2% protein solution (Soybean-Protein-Concentrate or Porcine-Digestible-Peptides; PDP) and another flavour (CS-) mixed into water during 6 alternate sessions. Animals preferred the CS+ over the CS- flavours at all test days. No differences were observed between proteins. In a second experiment a conditioned flavour preference also enhanced the attraction to a protein (PDP) when the flavour and protein were combined showing a synergy effect between the CS+ and US attraction. Chapter 3 evaluate flavour preferences conditioned by the post-ingestive effect of nutrients. Pigs were trained during 8d with one flavour (CS+) into PDP or sucrose solutions on odd days and another flavour (CS-) into 100 mM of monosodium glutamate (MSG) or 1% sucrose + 0.08% saccharine solutions on even days. Piglets showed higher intakes for CS+ than CS- explained because an associative learning between flavours and post-ingestive effects of nutrients. Chapter 4 describes social learning of feeding behaviour in pigs, in which a naive animal could learn specific flavour preferences by a close and brief contact with a conspecific. Piglets showed a preference for flavoured feed following social interactions (30 minutes) with an experienced demonstrator that ate that flavour before. However, higher intakes of demonstrators consumed flavoured feed were observed only when demonstrators and observers were familiar. Chapter 5 study the importance of milky flavour continuity in the post-weaning period and explore the influence of pre and postnatal exposure to PDP via maternal diet on the productive performance of post-weaned piglets fed a diet containing the same protein. No differences were found between the productive parameters of animals fed with dairy or PDP diets. However, animals showed a higher preference and acceptance for diets containing dairy products than for PDP diets (30 minutes choice and one feeder test). When the PDP was added to sows diets, post-weaned piglets tended to show higher ADFI and ADG than control piglets (15-33d after weaning). It is concluded that pigs may learn to prefer neutral flavours cues by a previous associative learning with a positive consequence. Flavour preferences learned through maternal transference, associative learning with nutrients and social interactions could increase pigs options to fit against new environment feed cues. These three ways of learning could act also together increasing the adaptive value of the learned feed.

The transition from mechanical ventilation (MV) to spontaneous ventilation during weaning is associated with hemodynamic alterations and autonomic nervous system (ANS) alterations (reflected by heart rate variability [HRV]). Although cardiac dysrhythmias are an important manifestation of hemodynamic alterations, development of dysrhythmias during MV and weaning and subsequent impact on length of MV has received little attention. The purposes of this dissertation were to 1) evaluate the relationship of heart rate variability (HRV) during weaning to the development of cardiac dysrhythmias and 2) determine the relationship of cardiac dysrhythmias to length of MV. A convenience sample of 35 patients (66.7% men; mean age 53.3 years) who required MV was enrolled in this study. Continuous 3-lead electrocardiographic data were collected for 24 hours at baseline during MV and for the first 2 hours during the initial weaning trial. HRV was evaluated using spectral power analysis. Twenty- seven patients out of 30 were exposed to a combination of pressure support (8-15 cm H2O) and continuous positive airway pressure 5 cm H2O during weaning trial. Three patients self- extubated and received supplemental oxygen through either a partial rebreathing or non-rebreathing mask. Low frequency (LF) power HRV decreased, while high frequency (HF) and very low frequency (VLF) power HRV did not change during weaning. Multiple regression analyses showed that LF and HF HRV were significant predictors of occurrence of ventricular and supraventricular ectopic beats during weaning, while VLF power predicted occurrence of ventricular ectopic beats only. The mean of occurrence of supraventricular ectopic beats per hour during weaning was double the mean at baseline, while the mean of ventricular ectopic beats per hour did not change. Mean number of supraventricular ectopic beats per hour during weaning was a significant predictor of length of MV. This dissertation has fulfilled an important gap in the evidence base for cardiac dysrhythmias during weaning from MV. Cardiac dysrhythmias and HRV alterations should be systemically evaluated during MV and weaning trials in order to decrease length of MV.

The goal of a cow-calf producer is to produce a calf each year per cow. Research suggests that first year heifers struggle breeding back with their second calf because of the adjustments to new range/main herd conditions and the partitioning of nutrients between gaining weight, milk production, and gestation. This study was conducted at the V-V ranch at the University of Arizona for five years and looked at the effects on young cows when calves were weaned from first year heifers at 80 days rather than 205 days. Early weaning allows for gestational benefits because they are given the opportunity to adapt to herd conditions by applying feed resources to the in utero fetus and their own body condition rather than lactation. All first year heifers were included over three years, and were randomly assigned to two groups, normal weaning (NW) or early weaning (EW). This resulted in 122 heifers in the group whose calves were EW and 119 heifers in the group whose calves were NW. Heifers that were in the EW group bred back at a 27% higher rate in their second year, and had 15% greater longevity in the herd. Calves that were in utero when the nursing calves were early weaned were 16.4 kg heavier at weaning. Part of this was due to the age of the calf and part to gestational health. Early weaning was an effective strategy for improving reproductive performance of first year heifers as well as their survival rate in the herd to 5 years of age. It also resulted in improved performance for their in utero calves.

A program of study was undertaken to asses the effect of pre-weaning feeding behaviour on post-weaning feeding behaviour in pigs weaned at various ages (3, 4 and 5 weeks of age) and to identify ways of increasing their post-weaning feed intake. The studies were constructed using time extensive continuous recording methods in order to monitor the 'true' behaviour unbiased by sampling errors. Piglets weaned at 3 weeks of age had the ability to grow faster and became significantly heavier at six weeks of age (3W: 12.S06 ± 0.629 kg) than piglets that had to extent their stay for one (4W: 10.S14 ± 0.693 kg) or two more weeks (SW: 10.987 ± 0.376 kg) with the sow. In addition, 4W piglets had the greatest difficulty adapting to their new environment in comparison to 3W and SW piglets, as they had greater scores on aggressive and abnormal behaviour during the week post-weaning. This study demonstrated that the provision of a familiar feeder post-weaning i) allowed all 4W piglets, irrespective of their pre-weaning feeding experiences, to allocate the feeding resources unaided and autonomously without having to rely on the feeding temperament of their more experienced littermates or having to imitate them eating, ii) helped the less experienced piglets of the litter (regarding their feeding behaviour) to build a stronger immune system and to become heavier at the end of the first week and iii) improved the welfare of the piglets soon after weaning as they were performing significantly less belly-nosing in contrast to equivalent piglets that were not suited with a familiar feeder. Also, extensive pre-weaning feeding behaviour can help 4W piglets obtain a stronger immune system by the end of lactation independent of their weight and their teat order. The study reported in this thesis provides good evidence that choosing to use a time-period which was previously applied by other researchers could lead most of the times to incorrect conclusions. Also, short time-sampling strategies have been proven to be insufficient to provide strong or valid statistical associations with the 'true' duration of the behaviours under investigation (r<70%). Continuous weekly recordings during the day hours (8:00 to 17:00h) were shown to be sufficient to provide measurements of strong association with the 'true' duration of the behaviours for the given week.

Background: The colon is believed to salvage energy from unabsorbed starch especially when the capacity of the small intestine to digest it is limited. The extent to which this occurs is not known. Aims: The aim of this thesis was to determine site and relative extent of starch digestion and fermentation in young children using the individual and combined approaches of stable isotope breath tests and in vitro stool fermentation models. Stable Isotope Breath Test Methods: Thirteen children (10m, 3f), median (range) age 11.8 mo (7.6 -22.7 mo), took a starchy breakfast containing 13C labelled wheat flour following an overnight fast. Duplicate breath samples were obtained before breakfast and every 30 min for 12 h. Breath 13CO2 enrichment was measured by isotope ratio mass spectrometry and results were expressed as percentage dose recovered (PDR) for each 30 min. PDR data were analysed and mathematically curve fitted either assuming a constant estimate of CO2 production rate or adjusted for physical activity. Stable Isotope Breath Test Results: Mean ± SD cumulative 13C PDR (cPDR) at 12 h was 21.3% ± 8.4% for unadjusted data and 26.5% ± 11.6% for adjusted data. A composite fit of two curves fitted significantly better than a single curve. Curve fitting allowed estimation of cPDRs of small intestine (17.5% ± 6.5% and 22.7% ± 9.3% for unadjusted and adjusted data respectively) and colon (4.6% ± 2.9% and 6.3% ± 5.4 %). From these results it is speculated that the colon may account for up to 20% of starch digestion in young children. In Vitro Colonic Fermentation Methods: A simulated colonic environment was used to account for the fate of raw and cooked starch that was fermented in the colon of young children. A slurry was prepared from faecal samples of 6 infants (7-10 mo), 6 toddlers (16-21 mo) and 7 adults (24-56 years). Each slurry was anaerobically incubated with raw or cooked maize starch in MacCartney bottles in a shaking water bath. Parallel incubations were stopped at 4 and 24 h. The headspace gas volume was analysed for CO2 and methane. The culture supernatant was analyzed for the volatile short chain fatty acids acetate, propionate and butyrate (SCFA), lactate and residual starch. In Vitro Colonic Fermentation Results: There was a decreasing trend of SCFA production with age at 4 h which was not evident at 24 h. At 4 h, toddler stools produced the most CO2 followed by infants and then adults, but this trend was not seen at 24 h. Methane was detected in 3 adults only. Lactate was detected mainly at 4 h in children only. The production of SCFA at 4 h generally declined with age but the differences at 24 h were less marked, suggesting fermentation is a more rapid process in young children than in adults. A highly efficient energy salvage process may take place in the colon of young children. Calculations Using Both Data Sets and Conclusions: Using data from studies described in both parts of the dissertation, it has been possible to derive stoichiometric equations for the whole gut digestion of starch, and thereby calculate its potential energy. There are a number of limitations to the methodology and from assumptions that have been made, but this provides an attractive means to calculate relative roles of small intestine and colon to starch digestion in young children which in turn may form the scientific basis for nutritional advice given to mothers.

The aim of this study was to investigate cortisol and progesterone (P4) trends in hair from birth up to postweaning in Italian trotter foals. Hair sampling is non-invasive and hair concentrations provide retrospective information of integrated hormone secretion over periods of several months. Samples were collected at birth and at a distance of 30 days, collecting only regrowth hair, up to post weaning. From birth to 3 months, foals cortisol falls from 47.64±5.6 to 4.9±0.68 pg/mg (mean±standard error), due to the interruption of foetal-placental connection and progressive adaptation to extrauterine life. From the third month of life to post weaning concentrations don’t vary significantly, underlining a non-chronic activation of the HPA axis. Hair P4 significantly decreases in the first two samples (from 469.68±72,54 to 184.65±35.42 pg/mg). At 2 (111.78±37.13 pg/mg) and 3 months (35.96±6.33 pg/mg) hair concentrations don’t show significant differences. These concentrations are not due to interactions of the utero-placental tissues with foals, animals are still prepuberal and P4 isn’t produced by adrenals as a result of high stress. We could therefore hypothesize that the source of foal hair P4 could be milk, suckled from mares. The high individual variability in hair at 2 and 3 months is due to a gradual and subjective change in foal diet, from milk to solid food, and to the fact that mares do not allow to suckle. From fourth month to post weaning P4 concentration in hair remains around 37.56±6.45 pg/mg. In conclusion, hair collected at birth, giving information about last period of gestation, could be used along with traditional matrices, to evaluate foals maturity. Hair cortisol could give indications about foals capacity to adapt to extra-uterine life. Finally milk, configuring as a bringer of nutrients and energy and assuming the characteristic of a nutraceutical, could give fundamental information about parental care.

The aim of this study was to investigate cortisol and progesterone (P4) trends in hair from birth up to postweaning in Italian trotter foals. Hair sampling is non-invasive and hair concentrations provide retrospective information of integrated hormone secretion over periods of several months. Samples were collected at birth and at a distance of 30 days, collecting only regrowth hair, up to post weaning. From birth to 3 months, foals cortisol falls from 47.64±5.6 to 4.9±0.68 pg/mg (mean±standard error), due to the interruption of foetal-placental connection and progressive adaptation to extrauterine life. From the third month of life to post weaning concentrations don’t vary significantly, underlining a non-chronic activation of the HPA axis. Hair P4 significantly decreases in the first two samples (from 469.68±72,54 to 184.65±35.42 pg/mg). At 2 (111.78±37.13 pg/mg) and 3 months (35.96±6.33 pg/mg) hair concentrations don’t show significant differences. These concentrations are not due to interactions of the utero-placental tissues with foals, animals are still prepuberal and P4 isn’t produced by adrenals as a result of high stress. We could therefore hypothesize that the source of foal hair P4 could be milk, suckled from mares. The high individual variability in hair at 2 and 3 months is due to a gradual and subjective change in foal diet, from milk to solid food, and to the fact that mares do not allow to suckle. From fourth month to post weaning P4 concentration in hair remains around 37.56±6.45 pg/mg. In conclusion, hair collected at birth, giving information about last period of gestation, could be used along with traditional matrices, to evaluate foals maturity. Hair cortisol could give indications about foals capacity to adapt to extra-uterine life. Finally milk, configuring as a bringer of nutrients and energy and assuming the characteristic of a nutraceutical, could give fundamental information about parental care.

Breastfeeding involves phases of initiation, continuation, and weaning. Research to date has focused upon its initiation and continuation rather than the later phases, when the child is weaned from the breast. Selective aspects relating to weaning have been explored to determine infant feeding practices such as the timing of food introduction. However, that research has focused upon developing countries where the impact of infant feeding patterns and weaning practices have a significant impact on infant growth and child health. The weaning process or final phase of breastfeeding from the mothers' perspective has not been examined within the western world. In order to fully understand this important maternal task, all phases of the experience must be explored. The management of weaning is affected by cultural, social, developmental, and psychological factors and is reflected in distinct infant feeding practices across cultures. The purpose of this grounded theory study was to analyse the maternal process of managing the later stages of established breastfeeding and, ultimately, weaning the child from the breast within a Western Australian context. A minimum time of six weeks postpartum was regarded as established breastfeeding whereas weaning was defined as the process that begins when the mother and/or the child decide to stop breastfeeding. Using the constant comparative method, analysis of thirty-three participants' interview transcripts, field notes, nine postal questionnaires from fathers, and individual and discussion group interviews with child health nurses revealed a common social problem of incompatible expectations. All participants faced a dilemma in the management of their experience when personal expectations were found to be in opposition to others' expectations. Although the focus of this study was on weaning, a key finding was that participants' expectations on weaning could not be easily separated from their expectations regarding breastfeeding and mothering. Expectations in the areas of breastfeeding and weaning were interrelated as achievements or disappointments reflected upon mothering expectations. When faced with incompatible expectations from their child, partner, family, friends, health professionals, and society, these Western Australian mothers expressed feelings of confusion, self-doubt, and guilt. A process of constructing compatibility by adapting focus was adopted to compensate for this incompatibility and comprised three phases. Prior to engaging in this process, participants arrived at a turning point where individual tolerance levels of confusion, guilt, and self-doubt were reached. The first phase entitled shifting focus involved participants clarifying the relative importance they assigned to aspects of their breastfeeding. This clarification enabled them to take charge of their experience and reinforce personal expectations and goals. In the second phase, selective focusing, participants selectively chose to focus upon specific compatible sources to accentuate their influence and thereby diminish the impact of incompatible sources. When confronted with ongoing incompatible expectations throughout their experience, participants moved back to shifting focus to re-clarify personal expectations and reinforce subsequent decisions. During the final phase of confirming focus, mothers reflected upon their experiences and resolved decisions by verifying that their adapted focus achieved the desired compatibility. This substantive theory of the management of breastfeeding and weaning from the perspective of Western Australian mothers is discussed in relation to existing nursing and social science theories. Additionally, implications and recommendations based upon these findings are presented.

Background: The adverse effects of mechanical ventilation (MV) are a major health concern associated with poor outcomes and economic burden. Some populations, such as those requiring more than one attempt at the gradual removal of MV (weaning), are at risk for longer duration of MV and associated complications. Traumatically injured patients have a higher prevalence of positive illicit drug toxicology then the general population. The traumatically injured, positive for illicit drugs who requires MV, may experience the sequelae of withdrawal syndrome and violate the thresholds that allow weaning, leading to longer durations MV. Methods: A retrospective descriptive analysis of a convenience sample of 52 adult trauma patients from SJHMC admitted between January 1 to December 31, 2014 who presented positive for illicit drugs and required mechanical ventilation. This sample was analyzed to: 1) describe the characteristics of this specific sample, 2) determine the prevalence of a difficult-to-wean subsample, 3) describe the characteristics of this sample during weaning attempts, and 4) determine if the existing weaning protocol necessitates amending. Results: Samples ability to wean; 78.8% (n=41) simple weaning; 15.38% (n=8) difficult weaning; and 5.77% (n=3) prolonged. Zero cases of adverse effects of MV or withdrawal syndrome detected. There was no correlation between stimulant and/or depressant and ability to wean (p=0.662). There was no relationship between injury severity score (ISS) and weaning group (p=0.762). Characteristics identified included; male to female ratio 4:1 and majority with ISS score>24. Variables within weaning protocol were missing 25-84% of data. Conclusion: The ability to wean MV in this sample is similar to what is reported in the general population, suggesting that they are not at risk for difficult weaning or prolonged MV. This sample’s majority was comprised of more traumatically complex, young males than found in the general trauma population. Investigators were unable to analyze or amend the current protocol because of the large amounts of missing data indicating possible gaps in adherence and/or documentation. To our knowledge, this is the first project that describes ability to wean in the traumatically injured positive for illicit drug.

Konsekvenserna av långvarig ventilatorbehandling i form av ökat antal komplikationer och ökade kostnader är väl dokumenterade. Patienten behöver tränas ur ventilatorn med en adekvat metod, utan fördröjning. Urträningsprotokoll kan minska risken för ineffektiv vård och medicinska misstag genom att tillhandahålla en enhetlig strategi och gemensam terminologi. Syftet med studien var att beskriva innehållet i de ventilatorurträningsprotokoll som förekommer inom Svenskintensivvård. Studien utgjordes av en totalundersökning där samtliga svenska intensivvårdsavdelningar tillfrågades om de hade urträningsprotokoll. Protokollen analyserades utifrån manifest innehållsanalys. Fyra kategorier av urträningsprocessen urskiljdes: kriterier för urträningstart, åtgärder, utmattningskriterier och extubationskriterier. En dryg femtedel (21 %) av intensivvårdsavdelningarna i Sverige visade sig ha ett urtränings-protokoll. I de 16 protokollen återfanns 31 kriterier för urträningsstart, 8 åtgärder, 24 utmattningskriterier och 9 extubationskriterier. De vanligaste kriterierna för urträningstart samt utmattningskriterier stämde väl överens med vad internationella studier rekommenderar, emellertid har vissa urträningsprotokoll inkluderat ett stort antal av dessa kriterier. Trots detta återfanns inget kriterium i samtliga urträningsprotokoll. Prognoskriterier saknades i det närmaste helt i de svenska urträningsprotokollen. Åtgärderna uppvisar en mer samlad strategi där samtliga hade som första åtgärd att sänka andningsunderstödet, men även här hade vissa urträningsprotokoll inkluderat ett stort antal åtgärder. Terminologin som används var inte enhetlig vilket kan försvåra kvalitetssäkringen av protokollen.
The consequences of extended mechanical ventilation in the form of increased number of complications and high costs are well documented. The patient needs to wean with an adequate method without delay. Weaning protocols can reduce the risk of ineffective care and medical errors by providing common weaning strategy and terminology. The purpose of this study was to describe the contents of weaning protocols in Swedish intensive care units. The study consisted of a total survey, and all Swedish intensive care units were asked if they had weaning protocols. The protocols were analyzed on the basis of manifest content analysis. Four categories of the weaning process distinguished: readiness to wean criteria, guidelines for reduction in ventilatory support, fatigue criteria and extubation criteria. One fifth (21 %) of intensive care units in Sweden had a weaning protocol. In the 16 protocols 31 readiness to wean criteria, 8 methods for reduction of ventilatory support, 24 fatigue criteria and 9 extubation criteria where found. The most common readiness to wean criteria and fatigue criteria are well in line with what international studies recommends, however some weaning protocols included a large number of these criteria. Despite this no criteria occurs in all weaning protocols. Criteria to predict weaning outcome is almost completely missing in Swedish weaning protocols. The methods for reduction of ventilatory support showed a more united approach in which all lower ventilatory support as a first step. Even in this category some weaning protocols had included a large variety in methods for reduction of ventilatory support. The terminology used in the weaning protocols varies which makes quality evaluation difficult.

La mortalitat durant la lactació és probablement el major problema econòmic i de benestar a afrontar per les explotacions porcines. Davant aquesta problemàtica, el principal objectiu d’aquesta tesis doctoral és intentar identificar els principals aspectes que poden contribuir a incrementar la supervivència dels garrins durant la lactació i, al mateix temps, identificar i jerarquitzar les tasques de maneig més efectives realitzades al voltant del part. Quatre estudis s’han dissenyat per assolir els nostres objectius (chapter 4, 5, 6 and 7): Al primer estudi, es van portar a terme dos experiments per estudiar l’efecte sobre truges primípares i les seves garrinades que s’observa després d’allotjar les truges en grup durant la gestació i mantenir-les lleugerament sobrealimentades (PEN, n = 27 per Exp. 1; n = 10 per Exp. 2) en comparació a tenir-les en gàbies convencionals (STALL, n = 24 per Exp. 1, n = 9 per Exp. 2). Es va mesurar la grassa dorsal (BF) al inici i final de la lactació i es va registrar la mortalitat. Els garrins es van pesar i es va registrar la seva temperatura rectal (RT). Per l’Exp. 1 es va enregistrar el comportament d’un subgrup de truges. Per l’Exp. 2 es van analitzar cortisol salivar de les truges i la concentració en sang de TSH i T4 dels garrins. Les truges del grup PEN van mostrar major BF a l’inici de la lactació (P < 0.001). Es va observar una tendència a major concentració de cortisol en les truges del grup PEN a les 24 h d’estar a les gàbies de part (P = 0.070) i una tendència a passar-se més temps assegudes o dempeus la jornada anterior al part (P = 0.057). Els garrins nascuts al grup PEN van tenir nivells menors de T4 (P = 0.078). No obstant, els garrins del grup STALL tingueren major RT als 60 min de vida (P < 0.05) i van sobreviure en més nombre després de les primeres 48 h de vida fins al final de la lactació (P < 0.05). A l’Exp. 2, els garrins del grup STALL pesaven més (P < 0.05) i van tenir un guany mig diari durant lactació més elevat (P < 0.05). Les truges nul·lípares allotjades en grup i lleugerament sobrealimentades durant la gestació es veuen sotmeses a un major estrès al ser introduïdes a les gàbies de maternitat que les truges allotjades en gàbies convencionals durant la gestació. Aquest estrès matern pot comprometre la capacitat de termoregulació dels seus garrins. L’objectiu del segon experiment va ser el de desenvolupar, a partir del seu comportament, un sistema d’avaluació de la vitalitat dels garrins que guardés relació amb el seu posterior creixament i supervivència. Es van emprar 287 garrins provinents de 21 truges multípares. Els garrins es van pesar acabat el part i es van avaluar 4 paràmetres comportamentals en un petit tancat circular de 55 cm de diàmetre: capacitat de moviment (U), estimulació del braguer (U), nombre de voltes completes dins el tancat (N), i capacitat de cridar (S). A dia 1, 2, 3 i 17 es van pesar els garrins, i a dia 1, 2 i 3 se’ls hi va mesurar la RT. Es van realitzar anàlisis de regressió múltiple per la supervivència i creixement dels garrins fins el deslletament. El guany de pes dels garrins durant la lactació va estar influenciat pel pes al naixement (P < 0.001), el número de part de al truja (P = 0.024), el número de nascuts vius al part (P < 0.001), i pel sumatori dels paràmetres U i N (UN; P = 0.023). La capacitat de sobreviure dels garrins va ser influenciada pel pes al naixement (P = 0.015), pel paràmetre UN (P = 0.026), i per la RT a dia 3 (P = 0.085). El sumatori de la valoració als paràmetres U i N, combinats amb el pes al naixement i la informació de la truja, són útils per ajudar a predir el potencial de creixement i la viabilitat del garrí durant la lactació, convertint-se en una possible eina per millorar el maneig durant els primers dies de vida dels garrins. Resumint, el paràmetre UN és fàcil d’obtenir i pot ser d’utilitat per avaluar els garrins tant per criteris científics com productius. El tercer estudi està centrat en estudiar diferents mesures de maneig orientades a maximitzar la presa de calostre per part dels garrins. Es van utilitzar 39 truges primípares (507 garrins) i 100 multípares (1375 garrins). Els garrins es van classificar en: nascuts amb un pes de 1.30 kg o inferior (SP) i nascuts amb un pes superior a 1.30 kg (BP). Les garrinades es va distribuir a un dels 4 tractaments: grup control (CON); deixar que els SP mamin durant 2 h separant els BP (SPLIT); subministrar oralment 15 ml de calostre de truja als SP (COL); i subministrar 3 ml d’un producte energetic (Calostrene®) als SP (EN). Es van fer el mínim d’adopcions, ajustant les garrinades a 12 garrins (mantenint 4 o 5 SP a cada garrinada). Els garrins es van pesar al dia 1 i 18 de vida, i es va registrar la mortaitat. En les garrinades de primípares, els SP del grup COL van pesar més que els de CON, SPLIT i EN a les 24 h de vida (dia 1) (P = 0.020, P = 0.022, and P = 0.046, respectivament). Malauradament, aquesta diferència no es va observar a dia 18. En les garrinades de multípares no es van observar diferències de pes durant la lactació entre els diferents grups. Tot i que entre les garrinades de primípares i multípares els SP no diferien en pes al naixement, a dia 1, els SP de primípares eren més pesats (P = 0.020). Malgrat aquestes circumstàncies, no es va reduir la mortalitat a les garrinades del grup COL (ni en primípares ni en multípares). La complementació oral millora el guany de pes durant el primer dia de vida dels garrins SP nascuts de primípares, però no ajuda a reduir la mortalitat durant la lactació. En el quart i últim experiment es va estudiar l’efecte d’aportar calostre als garrins nascuts amb un pes igual o inferior a 1.35 kg (SP) (CON: grup control; COL:subministrar oralment 15 ml de calostre de truja), i l’efecte de realitzar adopcions a les 24 h (HL: ajustar garrinades a 12 garrins amb 4 o 5 essent SP; o LL: majoria dels garrins de al garrinada essent SP). Combinant els dos factors s’obtingueren 4 tractaments: CON-HL, CON-LL, COL-HL, COL-LL. Els garrins de 46 garrinades es van pesar també a dia 1 i 19, i la mortalitat es va registrar. Al dia 4 de vida, es va extreure sang de 79 garrins SP per analitzar la concentració d’IgG, i també de 8 garrins SP separats de la truja durant 12 h i alimentats artificialment que es van utilitzar com a control negatiu. Les garrinades LL tenien un CV del pes a dia 1 menor comparat amb el grup HL (16.2 vs. 21.9 ± 0.91%, P = 0.003), però no diferien pel mateix paràmetre a dia 19 (23.2 vs. 23.4 ± 1.72%; P > 0.10). A dia 19, les truges HL van tenir menys garrins morts per garrinada que les truges LL (0.80 vs. 1.69 ± 0.307; P = 0.022) i les truges del grup COL-HL van tenir menys garrins morts per garrinada que les CON-HL (0.47 vs. 1.14 ± 0.160; P = 0.062). Les adopcions dels SP per formar garrinades LL no va aconseguir reduir el CV de pes de al garrinada al deslletament. Els garrins del grup COL van tenir major concentració de IgG que els del grup CON (P = 0.001); mentre que el grup control negatiu va tenir nivells de IgG inferiors a COL i CON (5.4 ± 2.32 mg/ml vs. 30.6 ± 1.58 mg/ml and 21.5 ± 0.95 mg/ml. respectively; P < 0.001 ambdós casos). Fer ‘garrinades de petits’ no va reduir la mortalitat ni va reduir el CV del pes de la garrinada. Donar calostre als garrins SP millora el seu estatus immunitari a dia 4. A més a més, en garrinades no homogeneïtzades, aportar calostre als garrins SP és una bona estratègia per millorar el seu rendiment.
Pre-weaning mortality in breeding herds remains as one of the most important welfare and economic problems in swine production. Therefore, the principal objective of the present thesis was to identify the main aspects that may help to reduce on-farm piglet pre-weaning mortality and to establish a management hierarchy identifying the most effective tasks around farrowing. To achieve our objective, four studies were performed (chapter 4, 5, 6 and 7): In the first study, two experiments were carried out to observe the effect of two gestation management systems (STALL: gilts housed in stalls with no changes in management, and PEN: slightly overfed gilts loose-housed in pens) on gilt and piglet performance. A total of 27 PEN and 24 STALL gilts and 10 PEN and 9 STALL gilts were used in Exp. 1 and Exp. 2, respectively. Backfat (BF) at the beginning and at the end of lactation, and litter pre-weaning mortality were recorded in gilts. Weight and rectal temperature (RT) was recorded in piglets. In Exp. 1 the behaviour of a subsample of gilts was continuously videotaped during lactation. In Exp. 2 cortisol in gilt saliva, and TSH and T4 in piglet blood were measured. In both experiments, PEN gilts had more BF than STALL gilts when moved to the farrowing stalls (P < 0.001). PEN gilts tended to have higher cortisol concentration 24 h after entering the farrowing stall (P = 0.070) and to spend more time sitting or standing up 1 day before parturition (P = 0.057) than STALL gilts. Piglets from PEN gilts had lower T4 (P = 0.078) than those from STALL gilts. However, piglets from STALL gilts showed higher RT 60 min after birth (P < 0.05) and lower mortality from 48 h after of birth until weaning (P < 0.05). In Exp. 2, piglets from STALL group also had higher BW (P < 0.05) and average daily gain (P < 0.05) at the end of lactation. During lactation, PEN gilts lost more BF than STALL gilts (P < 0.001). Gilts that are loose-housed and slightly overfed in pens during gestation may be more stressed when housed in farrowing stalls than those that have been kept in stalls during gestation, thus compromising their offspring thermoregulatory capacity and growth. For the second study, the aim was to develop a vitality scoring method based on piglet behavior and relate it to piglet growth and survival. From 21 sows, 287 piglets were used. After farrowing (day 0), piglets were weighed and tested for 4 behavioural parameters in a circular enclosure (55 cm diameter): movement capacity (M), udder stimulation (U), number of completed circles around the enclosure (N), and screaming (S). Piglets were weighed again on day 1, 2, 3 and 17. Piglet RT was recorded on day 0, 1, 2 and 3. Sow’s farrowing information was recorded. Multiple regression analyses for survival and BW gain at weaning as dependent variables was performed. Piglet BW gain at weaning was influenced by BW at birth (P < 0.001), sow parity (P = 0.024), total number of piglets born alive per sow (P < 0.001), and the sum of U and N parameters (UN; P = 0.023). Piglet survival during lactation was influenced by BW at birth (P = 0.015), UN parameter (P = 0.026), and RT on day 3 (P = 0.085). The sum of U and N parameters, in combination with BW at birth and information of the sow might be useful to predict piglet growth and survival during lactation, thus becoming a useful tool to improve piglet management during the first days of lactation. In conclusion, UN parameter seems to be an easy and useful way to assess piglet vitality for both scientific and commercial purposes. The third study focused on early management towards newborn piglets and its effect on piglet’s growth and survival. For the experiment, 39 primiparous sows and their litters (507 piglets) and 100 multiparous sows and their litters (1375 piglets) were used. Piglets were classified according to their BW at birth: SP, piglets born weighing 1.30 kg or less; and BP, piglets born weighing more than 1.30 kg of BW. Litters were allocated to one of the 4 treatments: control group (CON); split nursing of the BP piglets of the litter for 2 h allowing SP piglets free access to teats (SPLIT); orally supplementation with 15 ml of sow colostrum to the SP piglets of the litter (COL); and orally supplementation with 3 ml of an energetic product (Calostrene®) to the SP of the litter (EN). Cross-fostering was performed at a minimum level, fixing litters at 12 piglets (all the litters had 4 or 5 SP piglets). Piglets were weighed again on day 1 and 18 post-partum. Mortality was recorded. For primiparous sows oral supplementation with COL enhanced SP BW at day 1 compared to CON, SPLIT, and EN (P = 0.020, P = 0.022, and P = 0.046, respectively). However no differences were observed at day 18. For multiparous sows, no differences among treatment groups were observed for SP BW at day 1 and at day 18. Although there were no differences between gilts and multiparous sows for SP birth weight, gilt’s SP had higher BW at day 1 than sows’ SP (P = 0.020). Despite its effect on SP piglets’ BW at day 1, COL did not reduced pre-weaning mortality within gilt’s litters or within multiparous sows. Colostrum supplementation of low birth weight piglets enhanced their colostrum intake improving weight gain in piglets born from gilts. But it did not affect piglet’s weaning BW or pre-weaning mortality. The fourth experiment studied the effect of oral supplementation of piglets born weighing 1.35 kg or less (SP) (CON: control group; COL: 15 ml of sow colostrum fed within 4 h after birth), and the effect of cross-fostering 24 h after farrowing on litter performance (HL: litters fixed at 12 piglets, with less than 50% of the piglets being SP, aiming to as minimum movements of piglets as possible; LL: litter fixed with most of the piglets being SP) on litter performance. The combination of the 2 management strategies described above resulted in a 2 x 2 factorial model. Forty six litters were used. Litters were allocated to 1 of the 4 treatments: CON-HL, CON-LL, COL-HL, COL-LL. Piglets were weighed on day 1 and 19 post-partum. Mortality was recorded. On day 4 post-partum, a 2 ml blood sample was obtained from 79 SP piglets born from multiparous sows included in the experiment. To obtain a negative control group, blood samples were obtained on day 4 post-partum from 8 extra SP piglets that were separated from their mothers at birth and bottle fed with milk replacement for 12 h. LL sows had lower within litter CV of BW at day 1 than HL sows (16.2 vs. 21.9 ± 0.91%, P = 0.003) but they did not differ for litter CV of BW at day 19 (23.2 vs. 23.4 ± 1.72%; P > 0.10). At day 19, HL sows had lower number of dead piglets per litter than LL sows (0.80 vs. 1.69 ± 0.307; P = 0.022) and COL-HL sows had lower number of dead piglets per litter than CON-HL (0.47 vs. 1.14 ± 0.160; P = 0.062). Cross-fostering SP at the same litter did not prevent from increasing litter’s CV of BW at weaning. Piglets from COL group had higher IgG concentration than piglets from CON group (P = 0.001). While piglets from the negative control group had lower IgG concentration than COL and CON groups (5.4 ± 2.32 mg/ml vs. 30.6 ± 1.58 mg/ml and 21.5 ± 0.95 mg/ml. respectively; P < 0.001 in both cases). Allocating small piglets to the same litter through cross-fostering had a negative effect on mortality and did not improve litter CV of BW at weaning. Colostrum supplementation of SP piglets improves immune status at day 4. Besides, in non homogenized litters, coslostrum supplementation of SP piglets might be a good management strategy to improve litter performance.

Anguilla australis glass eels proved to be resilient and present strong aquaculture potential. General husbandry techniques, anaesthesia and prophylactic treatments were established for glass eels between 0.1 g and 2.0 g and elvers between 2.0 g and 8.0 g, caught in rivers and estuaries along the South East Coast of Victoria. The protozoan parasites Ichthyobodo and Trichodina were found to be present on arrival to the hatchery developed during different rearing treatments, and were successfully eradicated. A. australis glass eels accepted artificial food, but it was recommended first be fed a preweaning diet of minced fish flesh. A weaning regime from minced fish flesh to commercially available eel grower mash, over 15 days was established. Growth rate proved to be highly variable, both between and within groups. The highest growth rate of 2.71%/day was found when the natural diet of minced fish and Artemia was fed. The maximum growth rate when reared on an artificial diet of 1.63%/day was observed at 25°C. Growth was affected by the presence or absence of a preweaning diet, weaning diet, weaning period, temperature, but not by size or density. Once weaned, glass eels were found to perform better on commercially available grower mash than on the minced fish flesh, which was used to aid in weaning them to artificial diets. Of the water quality parameters measured stocking density was found to affect pH, Total Ammonia Nitrogen, Total Phosphorus, and Dissolved Oxygen, through not to an extent which affected growth.

This PhD researched the subject of low feeding behaviour of the newly weaned piglet in the immediate post-weaning period. The main aim of this research was to investigate techniques to better manage the vulnerable animal in the critical post-weaning period in order to improve feed initiation and intake. Leeds University Feeding Behaviour System was tested and validated for recording the feeding behaviour of piglets housed in groups. Creep feed experience did not improve feeding behaviour post-weaning. Lack of experience of solid feed was not detrimental to the piglets. Outdoor-reared. piglets showed reduced feeding initiation and behaviour compared to indoor-reared piglets when weaned into an indoor facility. questioning the welfare implications of this common management technique. Grouping of piglets, at weaning, from different backgrounds did not conclude any effects of social facilitation between the piglets. However, keeping pig1ets with their siblings led to better feeding initiation and improved growth performance. The feeding behaviour of three crossbreeds of pig was different. Hampshire and Pietrain breeds initiated feeding sooner than Large White piglets. The three-breed crosses had different feeding patterns, with Hampshire piglets recorded as the crossbreed with the highest feeding behaviour in the first week post-weaning. When provided with a choice, piglets rejected ZnO supplemented food in favour of an unsupplemented food. Even in the presence of Post-Weaning Colibacillosis there was no indication of selection to meet a requirement. In addition, there was no indication of selection to meet a lysine requirement by weaned piglets. When offered a choice between high and low lysine foods, the piglets' fed entirely at random. Random behaviour was also found from analysis of Short Term Feeding Behaviour, concluding the unsuitability of log-normal analysis for these animals. It is clear that the establishment of feeding by the piglet is a complex area, and further research is warranted.

This study explored the factors which affect the feeding and weaning practices of Emirati mothers as well as the experiences and perceptions which influence their breastfeeding decisions. It used both quantitative and qualitative methods to examine Emirati mothers’ understanding of infant feeding and to identify the factors which appeared to have a relevant effect and locate them in their cultural context. n the survey, a convenientce sample of 593 mothers with infants aged up to 2 years was interviewed face to face in the maternal and child healthcare centers in Al Ain, Dubai and Abu Dhabi. The interview was based on a pretested structured questionnaire. The results of multiple logistic analysis showed that the time of initiation of the first breastfeed was significantly associated with the infant’s birth weight (OR=2.007; P<0.023), parity (OR=2.139; P<0.001) and rooming in (OR=21.70; P<0.001). As for the feeding patterns, the results of the multiple logistic analysis revealed that rooming in (OR=4.485; P<0.001), feeding on demand (OR=2.290; P<0.005) and feeding more frequently at night (P<0.001) emerged as significant factors associated with exclusive or almost exclusive breastfeeding practices. The duration of breastfeeding rate was significantly influenced by many variables. Concerning the duration of lactational amenorrhea, the, the multiple logistic analysis showed that mother's age, breastfeeding duration and the early introduction of formula milk and solid food emerged as significant variables. Among the 593 infants in the study, 24.1% were predominantly breastfed,25% of the infants were exclusively breastfed, and 49.4% were almost exclusively breastfed since birth. Fifteen Emirati mothers from each city were interviewed about their breastfeeding practices, beliefs and perceptions. The following themes emerged: the influence of others, the sources of information, infants’ behavior, knowledge of and attitudes towards current WHO recommendations and mothers’ perception of the benefits of breastfeeding. Health promotions and healthcare facilities failed to deliver the message of the importance of exclusive breastfeeding. Grandmothers and mothers-in-law appeared to influence the mother's breastfeeding practices. In conclusion, there is a need for a national community-based breastfeeding intervention programme for the promoting exclusive breastfeeding practices as part of a primary public health strategy.

Doctor of Philosophy
Department of Animal Sciences and Industry
KC Olson
We evaluated effects of preconditioning on performance and health of beef calves raised and finished in the Great Plains. In experiment 1, calves were preconditioned for 0, 15, or 45 d and vaccinated against BRD-causing pathogens 14 d before maternal separation or after feedlot arrival. During receiving and finishing, preconditioned calves had greater DMI and ADG than non-preconditioned calves; however, timing of BRD vaccination did not affect animal health. In experiment 2, calves were vaccinated against BRD pathogens 0, 1, 2, or 3 times during a 30-d preconditioning program. Vaccination for BRD, regardless of degree, improved health during preconditioning; however, DMI, ADG, and G:F during preconditioning, receiving, and finishing were unaffected by degree of vaccination. In experiment 3, calves were preconditioned for 30 d, shipped 4 h to an auction facility, commingled for 12 h, and transported 4, 8, or 12 h to a feedlot. Feedlot performance and health of beef calves were not affected by transport of up to 12 h following auction-market commingling. In experiment 4, beef calves were subjected to 1 of 3 ranch-of-origin preconditioning programs: drylot weaning + abrupt dam separation, pasture weaning + fence-line contact with dams, and pasture weaning + fence-line contact with dams + supplemental feed delivered in a bunk. Drylot-weaned calves gained more weight during preconditioning. Unsupplemented, pasture-weaned calves had the least ADG during receiving but had greater ADG during finishing and had carcass characteristics similar to other treatments. In experiment 5, we evaluated performance of early-weaned beef calves fed grain-based diets with DMI adjusted to achieve ADG of 0.45, 0.91, or 1.36 kg/d during an 84-d growing period. Calves fed at restricted rates did not exhibit improved G:F relative to full-fed counterparts. In addition, there appeared to be limitations associated with predicting DMI and ADG of light-weight, early-weaned calves fed a grain-based diet.

Post-weaning is the most crucial period in pig management. Associated with weaning are marked changes to the histology and biochemistry of the gut which cause decreased digestive and absorptive capacity and contribute to post-weaning diarrhoea. In last years, the interest in developing management and feeding strategies to stimulate gut development and health in newly-weaned pigs was increasing. In order to increase general health in post-weaning piglets and be alternative to in-feeding antibiotic, three trials were created in this thesis to determine the utilizations of some functional foods which have been widely used to improve growth performance while minimizing the use of antibiotics and rather expensive feed ingredients in weaned piglets. We utilized essential oils (Thymol and Cinnamaldehyde, EO) and/or enzymes (Xylanase and β-glucanase, XB) in the first 2 trials. The first trial mainly focused on the effects of those additives on general parameters such as performance and digestibility of weaned piglets. To investigate the possible protective effects of EO and/or XB on health status in weaned piglets, we created a model of challenge using Escherichia coli in the second trial. After first two investigations, we intended to enlarge the categories of functional foods and determine the effects on regulation of systemic inflammatory reaction and, in addition, we supposed that initial body weight might also influence the regulation. Therefore, the third trial was desined to determine the effects of dietary cocktail (bovine colostrums, cranberry extract, encapsulated essential oil, yeast-derived products, the probiotic Pediococcus acidilactici MA18/5M, vitamins A, D, E and B complex, seleno-methionine) and body weight on inflammatory cytokines and time responses under Lipopolysaccharides challenge in early weaned piglets. In the first trial, a total of 192 weaned piglets (Stambo HBI Dalland 40, 24 d) with an average initial body weight of 8.10 kg were allocated according to body weight into 4 experimental treatments (12 replicates per treatment with 4 piglets per replicate). Each group was fed the basal diet alone or supplemented with either essential oils or enzymes, or their combination. There was no effect of essential oils and/or enzymes supplementation on the growth performance of piglets. However, the combination of essential oils and enzymes decreased feed conversion ratio during the last week. Although the fecal digestibilities of all the piglets were increased from d 21 to 35 (P < 0.001), no effect of essential oils or enzymes or the combination on the fecal digestibility was observed. All the additives significantly decreased counts of Coliforms at 42 days of the trial (P < 0.001). Dietary enzymes improved gut morphology by decreasing crypt depth, increasing villus:crypt ratio and reducing the number of macrophages (P < 0.001). Supplementation of essential oils and the combination with enzymes also improved gut morphology by decreasing crypt depth (P = 0.065; P < 0.001), and decreasing the number of lymphatic follicles (P = 0.002; P < 0.001) and macrophages (P < 0.001). No effect of additives on mRNA expression of inflammatory cytokines was observed in ileal mucosa. Results showed that diet supplementation with EO and/or XB had positive effects on intestinal bacterial counts and gut morphology, although there was no significant diet effect on grow performance or digestibility. In the second trial, 192 weaned piglets (Stambo HBI Dalland 40, 8.64 kg) were allocated according to body weight into eight experimental treatments (6 replicates per treatment with 4 piglets per replicate). The treatments were in a factorial arrangement: 1) dietary treatments [a weaned piglet control diet (CTR), CTR + 0.05 g/kg essential oils (EO), CTR + 0.1 g/kg enzymes (XB), and CTR + 0.05 g/kg EO + 0.1 g/kg XB] and 2) with or without an E. coli challenge. On d 8, half of piglets in each dietary group were challenged with E. coli. E. coli challenge significantly impaired growth performance, induced severe diarrhea, increased populations of E. coli, Clostridia and Coliforms, depressed antioxidant activities, damaged gut morphology and promoted TLR-4 and TNF-α mRNA expression in ileal mucosa (P < 0.05). In the E. coli challenge group, dietary enzymes or combinated with essential oils improved feed efficiency compared with control treatment during the last week (P = 0.025; P = 0.020). The Coliforms populations in the cecum of challenged piglets fed combination of essential oils and enzymes were lower than control treatment (P < 0.001). In the E. coli challenge group, supplemented essential oils and/or enzymes improved gut morphology by increasing villus height and villus:crypt ratio and decreasing crypt depth (P < 0.001). The positive effects on intestinal bacterial counts and gut morphology suggests that supplementation of EO and/or XB might improve the protective capacity against pathogenic bacteria when piglets were submitted to a bacterial challenge. In the third study, a total of 256 Yorkshire × Landrace weaned piglets (20 ± 1 d) were allocated into eight experimental treatments (8 replicates per treatment with 4 piglets per replicate). The treatments were in a factorial arrangement: 1) dietary treatments: a basal weaning diet added [spray-dried plasma protein (PP) (CTR), PP + antibiotic (ATB), PP + dietary cocktail (DC), or bovine colostrum + the dietary cocktail (BC+DC)] and 2) low weight (LW) or high weight (HW). At 37 d of age, 2 piglets in each pen were injected with LPS. Stimulations of LPS and PMA in PBMCs of piglets significantly induced TNF-α, IL-8 and IL-10 (P < 0.05). There was no diet effect on the concentrations of TNF-α, IL-8 and IL-10 in PBMCs of piglets (P > 0.05). Piglets had low weight tended to increase the concentration of IL-8 (P = 0.106) and IL-10 (P = 0.098) in the PBMCs stimulated by LPS 0.5µg/ml LPS and the concentration of IL-10 (P = 0.097) in PMA stimulated PMBC compared with high weight animals. Infection with LPS increased (P < 0.001) serum concentrations of all the cytokines four hours post inoculation, and animals recovered to basal levels at 18 h after challenge. No significant diet effect was found in the serum concentrations of cytokines (P > 0.05). At 4 h after challenge, low weight piglets had partially greater serum concentrations of TNF-α (P = 0.046), IL-6 (P = 0.158), IL-8 (P = 0.179) and IL-10 (P = 0.185) than high weight animals. Dietary cocktail or combined with bovine colostrum may replace plasma protein and antibiotics and weight difference may influence the production of inflammatory cytokines after infected by LPS. In conclusion, we observed that supplementation of functional foods as essential oils and enzymes might strengthen protective capacity of weaned piglets against pathogenic bacteria by decreasing negative intestinal bacterial counts and improving gut morphology. Dietary cocktail or combined with bovine colostrums, at the amount used in this work, may replace plasma protein and antibiotics. Besides, weight difference may influence the production of inflammatory cytokines after infected by LPS.

Foram realizados dois experimentos para determinar a composição química, os coeficientes de digestibilidade de nutrientes e os valores de energia e proteína digestíveis do ovo em pó (OP) e avaliar o desempenho e os componentes sanguíneos e plasmáticos de leitões recém-desmamados alimentados com dietas contendo níveis crescentes de proteína do OP em substituição à proteína do plasma sanguíneo. O Experimento I consistiu de um ensaio de digestibilidade, sendo utilizados oito leitões (quatro machos castrados e quatro fêmeas), mestiços Landrace x Large White com 15,9 kg de peso médio. Os tratamentos consistiram de uma dieta basal e uma dieta teste (70% dieta basal + 30% OP) com quatro repetições cada. Utilizou-se a metodologia da coleta parcial de fezes com o uso de 0,5% de óxido crômico (Cr2O3) adicionado às dietas como indicador. Os coeficientes de digestibilidade aparente do OP foram de 87,18, 80,76, 81,99 e 70, 54%, respectivamente, para a matéria seca, energia bruta, proteína bruta e extrato etéreo. A partir dos coeficientes de digestibilidade determinados e os valores de proteína bruta (56,53%) e energia bruta (5.897 kcal/kg) foram calculados os valores de 43,91% de proteína digestível e 5.139 kcal/kg de energia digestível do OP para leitões em fase de creche. No Experimento II, foram utilizados 90 animais (machos castrados e fêmeas), mestiços Landrace x Large White, desmamados com 24 dias e 5,6 kg de peso médio. O período experimental compreendeu duas fases, a pré-inicial (1 a 14 dias) e inicial (15 a 28 dias pós-desmame), onde os tratamentos consistiram de cinco rações isonutritivas com níveis crescentes (0, 25, 50, 75 e 100%) de substituição protéica do plasma sanguíneo da dieta pelo OP. O delineamento experimental foi o de blocos casualizados, com nove repetições por tratamento e dois animais por unidade experimental (baia). Os animais e a ração foram pesados para o cálculo do ganho diário de peso (GDP), consumo diário de ração (CDR) e conversão alimentar (CA) em cada fase e período total. Ao final do ensaio de desempenho foi retirada uma amostra de sangue de cada animal para a determinação dos componentes plasmáticos (uréia, proteína total, albumina, globulina, relação albumina/globulina, triglicérides e colesterol) e sanguíneos (hematócrito e hemoglobina). Não houve diferença entre os tratamentos (P > 0,05) para as variáveis de desempenho na fase de 1 a 14 dias pós-desmame. Para a segunda fase experimental e para o período total, foi observada uma redução linear (P < 0,01) do GDP e CDR, à medida que aumentava o nível de substituição do PS pelo OP. Para as variáveis dos componentes plasmáticos e sanguíneos não foram observadas diferenças significativas (P > 0,05) entre os tratamentos. Concluiu-se que o ovo em pó pode substituir completamente o plasma sanguíneo sem afetar o desempenho dos animais na fase de 1 a 14 dias pós-desmame, enquanto que na fase de 15 a 28 dias essa substituição prejudicou o desempenho dos animais, refletindo assim, em um pior desempenho no período total (1 a 28 dias). A inclusão crescente do ovo em pó nas dietas não alterou os componentes plasmáticos e sanguíneos.
Two experiments were carried out to determine the chemical composition, nutrients digestibility and digestible energy and protein of spray-dried egg (OP) and to study the performance and plasma and blood components of weanling pigs fed a diets containing OP. In Experiment I, eight Landrace x Large White crossbred pigs (four barrows and four gilts), averaging 15.9 kg live weight were used for digestibility assay. The animals were assigned to two treatments and four replications/treatment. The treatments consisted of the basal diet and test diet (70% of basal diet + 30% of OP) The method was the partial faeces collection, using 0.5% of chromium oxide (Cr2O3) in the diet as fecal marker. The apparent digestibility coefficients of dry matter, gross energy, crude protein and crude fat were, respectivily, 87.18, 80.76, 81.99 and 70.54%. From these results of apparent digestibility coeficients and the values of crude protein (56.53%) and gross energy (5,897 kcal/kg) resulted in 43.91% of digestible protein and 5,139 kcal/kg of digestible energy for OP. In Experiment II, ninety Landrace x Large White crossbred pigs (barrows and gilts) were weaned at 24 days of age with 5,6 kg live weight. The experimental period was divided in two phases, 1 to 14 days and 15 to 28 days post-weaning. The treatments consisted of five dietary levels of 0, 25, 50, 75 and 100 % of substitution of plasma protein for OP protein. Pigs were alloted in a randomized block design with nine replications per treatment and two pigs per experimental unit (pen). Pigs were weighed and the data of feed intake per pen were registered every week. Pig performance data such as average daily gain (GDP), daily feed intake (CDR) and feed conversion (CA) were analyzed by polynomial regression. No treatment effects (P > 0.05) were observed on performance for 1-14 day post-weaning phase. For the 15-28 phase and for the total period, linear reductions (P < 0.01) of GDP and CDR, were observed with increased dietary OP levels. No treatment effects (P > 0.05) were observed on plasma and blood components. Therefore, it can be conclued that the spray-dried egg can completely replace plasma without affecting the performance of pigs during 1-14 day post-weaning phase. For the 15-28 day phase and total period, added OP levels showed a depressive effect on pig performance. The plasma and blood components were not affected by the inclusion of spray-dried egg.

Die Erhöhung der tierischen Leistung von Nutztieren in den Tropen kann am schnellsten durch Kreuzungszucht realisiert werden. Ziel der vorliegenden Arbeit war es, die Leistung von Kamerun-Schafen (C) und Ihren Kreuzungen (Kamerun x Fleischschaf, F1) und (F2 aus Kamerun x Milchschaf) unter verschiedenen Fütterungs- und Haltungsbedingungen zu vergleichen. Folgende Merkmale wurden analysiert: - Wachstum vor dem Absetzen über 90 Tage; 127 Tiere; C, F1 und F2, - Wachstum nach dem Absetzen unter verschiedenen Fütterungsbedingungen; Wechsel vom 1,5-fachen des Erhaltungsbedarfs zu ad libitum Fütterung und umgekehrt; 6 Wochen Dauer; 30 Tiere; C, F1 und F2, - Haltung der Lämmer unter zeitlich begrenztem Temperaturstress (8 Stunden täglich bei 31°C und 50% rel. Luftfeuchte): Dauer 12 Wochen; 10 Tiere C und F, - Analyse von Schlachtkörpern nach Versuchsende jeden Versuches; 40 Lämmer, C, F1 und F2. Ergebnisse: - Während der ersten Aufzugphase zeigten die Kreuzungstiere mit 213g/Tag (F1) und 236 g/Tag (F2) eine um 50 bzw. 65% erhöhte Lebendmassezunahme gegenüber den Kamerun-Lämmern (143g/Tag). Die Differenz zwischen F1 und F2 resultierte aus der unterschiedlichen Milchleistung der Muttertiere. - Der zeitlich begrenzte Hitzestress führte zu keinen unterschiedlichen physiologischen Reaktionen zwischen den Rassen. - Es gab keine signifikanten Unterschiede hinsichtlich der relativen Körperzusammensetzung zwischen den Rassen. Die Kreuzungstiere hatten eine signifikant erhöhte Masse des Verdauungstraktes. Schlußfolgerungen: Kreuzungszucht zwischen indigenen und exotischen Rassen ist in den Tropen eine geeignete Methode die Fleischerzeugung zu erhöhen, allerdings nur, wenn die Futterversorgung gesichert ist. Hitzestress über eine begrenzte Zeit am Tag ist für die getesteten Rassen ohne Leistungseinbußen verträglich.
Crossbreeding between indigenous and exotic sheep breeds is the fastest method of increasing the performance of sheep in the tropics. The aim of this work was to assess the performance of Cameroon sheep (C) and their crossbreds (Cameroon x Mutton, F1) and (F2 from Cameroon x Milk sheep) under different housing and feeding conditions. The following traits were analysed: - Pre-weaning performance during the first 90 days; 127 animals, C, F1 and F2. - Post-weaning growth performance at different feeding levels; changing from 1.5 x maintenance to ad libitum feed intake and vice versa; duration 6 weeks; 30 animals; C, F1 and F2. - Housing of lambs under temporal heat stress (8 hours daily at 31°C and 50% relative humidity); duration 12 weeks; 10 animals, C and F2 - Carcass traits; 40 lambs, C, F1 and F2. Results: - During the pre-weaning period the crossbred lambs showed a higher live weight gain than the Cameroon lambs, 213g/d (F1); 236g/d (F2) and 143g/d (C) respectively, that is an increase of 50% and 65% resp. The differences between the F1 and F2 resulted from the different milk yields of the ewes. - The heat stress over 8 hours did not lead to different physiological reactions between the breeds. - There were no significant differences in the relative carcass traits between the breeds. The GIT-weight was increased significantly in the crossbreds. Conclusion: Crossbreeding of indigenous and exotic sheep breeds is a suitable method for increasing meat production in the tropics if the feed supply is guaranteed. Heat stress over a limited time is not crucial for the performance of all breeds.