Dissertations / Theses on the topic 'Fetal lamb'

To investigate the whole body metabolism of selenium (Se), isotope kinetic studies were undertaken in which indwelling catheters were implanted in the jugular veins of pregnant and nonpregnant ewes as well as the inferior vena cava and saphenous veins of 110-120 day (d) old ovine fetuses. A single injection of ⁷⁵Se-sodium selenite was administered and blood samples were obtained at various times. A 5 d Se balance trial, which commenced on the day of tracer experiment, was also undertaken. The plasma ⁷⁵Se specific activity data were used for determining the kinetic parameters of Se metabolism and the placental transfer rates. Using the Se balance and tracer data the net absorption and the fecal losses of Se were calculated. The fractional rate constants and T½ Se utilization in individual tissues were estimated by sacrificing the ewes and the fetuses at different times after the tracer injection and determining the tissue ⁷⁵Se specific activities. The effect of Se deficiency on the kinetics, placental transfer, net absorption and tissue metabolism was studied in a similar manner by feeding the ewes with Se deficient rations. The mean plasma Se concentrations in the positive nonpregnant and pregnant ewes were 142 187 ng/ml and were significantly higher than Se and the corresponding values (82 and 69 ng/ml) in the Se deficient ones respectively. The plasma Se levels in the Se positive fetuses (46 ng/ml) were not significantly different from the deficient ones (53 ng/ml). The irreversible disposal (ID) rates of Se were 7 ug/d/kg body weight (B.W.) in both nonpregnant and pregnant ewes, whereas, these values declined to 2 ug/d/kg B.W. under deficiency conditions. The ID values in the Se positive and deficient fetuses were 20 and 11 ug/d/kg B.W. respectively. These results indicated that the plasma Se turnover was lower in Se deficient animals than in the positive ones and that the fetuses had a higher turnover than adult ewes irrespective of the maternal Se status. Values for net Se absorption (% Se intake) and fecal Se losses (ug/d) in the Se positive nonpregnant ewes were 51% and 272 ug/d versus 97% and 25 ug/d in the Se deficient ones. The corresponding values for the Se positive pregnant ewes were 56% and 241 ug/d as against 84% and 27 ug/d in the deficient ones. These results suggested that the efficiency of net Se absorption expressed as the percent of Se intake decreased with increasing Se intakes and that the fecal route exerted a homeostatic control on Se metabolism in ewes. The tissue Se concentrations were significantly higher in the Se positive animals than in the deficient ones, whereas, the tissue fractional rate constant values were higher in the Se deficient animals than in the positive ones. These results implied that the tissue Se concentrations were significantly decreased under Se deficiency conditions and that the Se turnover was higher in tissues when the dietary Se intake was minimal. The placental transfer studies showed that there was a bidirectional exchange of Se across the placenta. The placental Se transfer rates from ewe to fetus declined from 53 ug/d in the positive ewes to 29 ug/d in the deficient ones. The rate of Se transfer from fetus to ewe also decreased from 24 ug/d in the positive ewes to 12 ug/d in the deficient ones. The net placental Se transfer was found to be reduced under conditions of decreased maternal dietary supply. The nutritional implications of Se status of the pregnant ewes on the availability of the trace mineral to the fetus have been discussed.
Land and Food Systems, Faculty of
Graduate

Ritodrine is a beta-adrenergic agonist commonly used to inhibit premature labor contractions in women. The primary goal of ritodrine tocolysis is to prolong gestation, however, other indications may include fetal distress. The purpose of the current study was to examine the metabolic and behavioral effects of ritodrine in the fetus, using the chronically instrumented pregnant sheep as an experimental model. Ritodrine was infused continuously into 11 fetal lambs at a rate of 2.6 ug/minute for a period of 8, 12 or 24 hours. Samples were taken simultaneously at predetermined time periods from a fetal femoral artery, umbilical vein, maternal femoral artery and uterine vein for the analysis of fetal and maternal arterial and umbilical and uterine venous blood gases, acid-base status, hematocrit, ritodrine concentration, uterine and umbilical blood flow, and glucose, lactate and oxygen concentrations and fluxes. Cardiovascular and behavioral variables were monitored continuously. The average concentration of ritodrine in fetal arterial plasma was 20.0 ± 2.7 ng/ml (range 9.5 to 3 4.7 ng/ml) at the end of the infusion. This concentration is within the range of cord levels obtained in ritodrine exposed human fetuses at birth (7 to 79 ng/mL) . Fetal arterial plasma ritodrine levels at 8 hours post-infusion were still sufficiently elevated to exert considerable fetal effects. The apparent tolerance of the fetus to given plasma levels of drug varied considerably among animals. The infusion of ritodrine resulted in many typical beta-adrenergic receptor mediated responses in the fetus. Fetal arterial glucose levels rose to 79% above the control by the end of the infusion. This was associated with an increase in fetal glucose delivery (70% above the control), a decrease in the umbilical veno-arterial glucose concentration difference and a tendency for fetal glucose uptake to decline. Fetal arterial plasma lactate concentrations rose more than fivefold during the infusion of ritodrine. This was associated with a rise in fetal lactate delivery (540% above the control), a slight increase in the umbilical veno-arterial plasma lactate concentration difference and a tendency for fetal lactate uptake to rise. Fetal oxygen consumption rose progressively and significantly throughout the infusion of ritodrine and during the first 8 hours of post-infusion, reaching a maximum of 22% above the control by 8 hours post-infusion. Umbilical blood flow remained unchanged, therefore umbilical oxygen delivery was not increased to meet the additional oxygen demands of the fetus. The rise in fetal oxygen consumption was hence accomplished through an increase in fetal fractional oxygen extraction (from a control value of 32.0±1.1% to a maximum of 51.6±1.8% by 1.5 hours of infusion). The rise in fetal oxygen extraction resulted in concurrent declines in fetal arterial Po₂ (78% of the control) and O₂ content (55% of the control) and a widening of the veno-arterial oxygen content difference. By the end of the infusion, umbilical venous Po₂ and O₂ content values had also fallen significantly to 78% and 75% of the control respectively. These latter changes resulted in a concurrent 25% decline in fetal oxygen delivery which in turn contributed to the rise in fetal oxygen extraction. Fetal arterial and umbilical venous pH declined rapidly and significantly from control values of 7.370±0.004 and 7.401±0.005 to 7.274±0.025 and 7.306±0.023 respectively by the end of the infusion. The acidemia was reflected by significant declines in base excess values and appeared to be entirely metabolic in nature, resulting from elevated blood lactate levels. The acidemia likely contributed to the progressive fall in fetal blood O₂ content through a rightward shift of the oxyhemoglobin dissociation curve (Bohr effect). The rise in fetal oxygen consumption was reflected by a similar (although nonsignificant) increase in uterine oxygen consumption. Uteroplacental oxygen consumption appeared to remain unaltered. The rise in uterine oxygen consumption was not accompanied by a corresponding increase in uterine oxygen delivery, hence uterine oxygen extraction rose to 23.8±1.9% (from a control value of 19.5±1.6%) by 1.5 hours post-infusion. The rise in uterine oxygen extraction resulted in significant declines in uterine venous Po₂ and CO₂ values which likely contributed to the fall in fetal oxygen delivery. Fetal heart rate increased significantly to 21% (34 beats per minute, bpm) above the control (162±7 bpm) during the first 1.5 hours of ritodrine infusion. It remained elevated by an average of 16% (26 bpm) throughout the remainder of the infusion and the first 8 hours of post-infusion, returning to the control by the end of the post-infusion period. Fetal arterial pressure remained unchanged from the control (46.2±1.5 mm Hg). The incidence of fetal breathing activity fell significantly from an overall average control value of 43.2±2.6% to an average of 28.1±6.8% during the ritodrine infusion period. In most animals, breathing was most depressed near the end of the infusion. The incidence of low voltage electrocortical (ECoG) activity also fell significantly by an average of 7.5% while that of high voltage ECoG rose by 7.3%. Alterations in intermediate voltage activity were not observed. The incidence of fetal rapid eye movement also tended to fall by an average of 8.2% during the infusion of ritodrine. These behavioral changes may have resulted from the development of fetal hypoxemia, rather than as a direct effect of ritodrine. In conclusion, these data have demonstrated that ritodrine infusion to fetal lambs results in significant physiological and behavioral changes in the fetus. These effects may put the fetus at risk, particularly in situations where fetal oxygen delivery is already reduced, as in various states of compromised pregnancy.
Medicine, Faculty of
Obstetrics and Gynaecology, Department of
Graduate

1. The aim of this project was to determine whether advancing gestational age and parturition were associated with alteration in the relative level of expression of genes encoding prostanoid receptors in key uterine and fetal tissues. I also sought to determine whether advancing gestational age and parturition were associated with alteration in the expression of genes encoding lipoxygenase (LOX) enzymes in key intra-uterine tissues. 2. Caesarean hysterectomy was performed on 15 pregnant baboons in the last third of pregnancy. Samples of myometrium (from multiple uterine sites), cervix, decidua and chorion were obtained. In addition, the ductus arteriosus was obtained from nine fetal baboons, 28 fetal lambs and 4 neonatal lambs. Expression of genes was studied using Northern blot analysis and in situ hybridization. Expression of genes was quantified by Northern analysis as a ratio of the signal for the gene of interest to each of three housekeeping genes (glyceraldehyde-3-phosphate dehydrogenase [GAPDH], beta-actin and cyclophilin). Statistical comparison of the effects of gestational age and labour was performed using linear regression. Student's t-test, repeated measures analysis of variance and analysis of covariance, as appropriate. 3 Initial studies of animals not in labour using cDNA probes demonstrated transcripts of similar size to the human genes for prostanoid EP2, EP3, EP4, and FP receptor mRNA using Northern blot in myometrium. Myometrium from the lower uterine segment (LUS) had greater expression of EP2 receptor mRNA and less expression of EP3 mRNA compared with the fundus and corpus. However, similar levels of EP4 and FP receptor mRNA were observed comparing the fundus and LUS. Expression of EP2, EP3 and EP4 receptor mRNA were also detected in cervix, decidua and chorion. EP2 mRNA was most abundant in cervix, EP3 was most abimdant in myometrium and EP4 mRNA was most abundant in decidua. The variation in myometrial expression of genes encoding EP receptor sub-types paralleled the contractile responses of paired samples (reported elsewhere). 4 When expression of prostanoid receptor genes was studied in myometrium obtained from animals both in labour and not in labour and the techniques employed were optimized (principally the use of riboprobes), transcripts of similar size to the human genes were detected for prostanoid EP1, EP2, EP3, EP4, IP, FP and TP receptor mRNA using Northern blot. There were no gestational age related changes in expression of these genes. Expression of EP1, EP3 and IP receptor mRNA was significantly higher in myometrium from the fundus (compared with lower segment) whereas EP2 gene expression was significantly lower in the fundus. Labor was associated with a reduction in the regional variation of both EP2 and IP receptor gene expression, but not EP1 and EP3 expression. Labor was also associated with an overall lower level of expression of EP2 receptor mRNA. 5 When expression of prostanoid receptor genes was studied in cervix obtained from animals both in labour and not in labour, clear signals which were similar in estimated size to the human genes were detected by Northern analysis for EP1, EP2, EP3, EP4, FP, IP and TP receptors. Expression of the gene encoding the prostanoid EP? receptor increased with advancing gestational age prior to labor. Expression of the EP2, FP and TP receptor genes was much lower in animals that were delivered during spontaneous labor than in animals which were not in labor. 6 When expression of prostanoid receptor genes was studied in decidua and chorion obtained from animals both in labour and not in labour, expression of the genes encoding the EP1 and FP receptor in decidua and the EP4 receptor in chorion was lower with advancing gestational age. Expression of the EP? receptor gene was lower in labour in decidua, whereas expression of the IP receptor gene was higher in labour in both decidua (2-fold) and chorion (4-fold).

Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.

The effects of reversible fetal tracheal occlusion (TO), and antenatal glucocorticoids on lung growth, structure, surfactant levels, and function were assessed in a lamb hypoplastic lung model of congenital diaphragmatic hernia (CDH). CDH, CDH+TO, CDH+TO+release of the tracheal occlusion one week before delivery (TR), and unoperated twin controls were compared. TO+/-TR partially normalized the hypoplastic lungs of CDH: they accelerated growth of both lungs and led to structural maturity. Only TO thinned the medial area of small pulmonary arteries closer to control values. Despite TO, TR, and glucocorticoids, lungs from lambs with CDH have dysfunctional type II cells with decreased surfactant levels. Nonetheless, CDH+TO lambs showed normal oxygenation, ventilation, and compliance over untreated CDH, with a clear survival advantage over an eight hour resuscitation. TR one week before delivery had no added benefit in terms of lung function. It appears that surfactant independent mechanisms such as pulmonary growth and structural changes are of foremost importance in relating to improved compliance, oxygenation, and ventilation of CDH+TO animals.

This study sought to maximize prenatal and postnatal interventions in order to accelerate lung growth and improve lung function in two animal models. Prenatal interventions consisted of fetal tracheal occlusion (TO), antenatal glucocorticoids and exogenous surfactant at birth (SURF) in an ovine model of congenital diaphragmatic hernia (CDH). CDH, CDH+TO, CDH+SURF, CDH+TO+SURF and unoperated twin control lambs were compared. Prenatal growth of both lungs was accelerated after fetal TO. Prophylactic surfactant did not improve gas exchange or ventilation but did increase lung compliance over 8 hours. The incidence of tension pneumothoraces was slightly decreased after exogenous surfactant. Fetal TO yields the best results in terms of overall postnatal lung function, likely acting via surfactant independent mechanisms.
Postnatal intervention involved perfluorocarbon (PFC) liquid distention of the right upper lobe in healthy newborn piglets. Postnatal lung growth, as measured indirectly by rates of DNA synthesis, was not accelerated after PFC distention.

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In this paper we proposed and analyzed methodologies using the technology of Cell-Free Fetal Nucleic Acid-Free (cffDNA = Cell Free Fetal DNA) in noninvasive prenatal diagnosis (NIPD). Due to the modern technologies employed and their repercussion among the involved families, we sought to discuss some ethical, social and legal implications. Contrary to the popular belief that the placenta forms an impermeable barrier between mother and child, there is bidirectional traffic between the fetus and mother during pregnancy. Several studies have shown that not only intact cells but also fetal cell-free fetal nucleic acids (cffNA, ie, DNA and RNA) cross the placenta and travels in the mother's bloodstream. Four different applications of analysis technology were identified: cffDNA: a) Prenatal Sex Determination, used in pregnancies under the risk of sexual transmitted diseases and performed through the detection of the Y chromosome b) The diagnosis of certain diseases of a single gene through the detection of paternally inherited mutation c) Fetal Aneuploidy, such as Down syndrome, where chromosomal abnormalities may occur d) identifying the type of fetal blood in pregnancies under the risk of incompatibility, especially RhD. To carry out this work it was used the pre-natal determination of sex in 53 pregnant women at different gestational periods. For that it was proposed and tested methods of DNA extraction, amplification of DNA obtained by PCR (Polymerase Chain Reaction) and a new methodology called LAMP (Loop Mediated Isothermal Amplification) and the analysis of final results. Furthermore, the efficiency of LAMP and PCR was compared by amplifying different segments of the Y chromosome: DSY14 and TSPY. In three cases the samples were discarded because there was no fetal sex confirmation after molecular tests due to loss of contact with pregnant women. In two other cases the results pointed to male fetuses whilst the ultrasound confirmed these fetuses as females due to contamination. Finally it was obtained 28 male samples (58.33%) with amplification of the sequences of the Y chromosome and 20 female samples (41.67%) that did not amplify the sequence of the Y chromosome but only for the control. These results showed that the amplification lamp is more efficient than PCR, in the analysis of DSY14, the limit of detection is 10 pg and 0.1 pg for LAMP and PCR respectively. It was concluded that the amplification using the LAMP method is faster (60 min) and has a high sensitivity and specificity and does not require sophisticated equipment for reaction if compared to the PCR method. These characteristics make this methodology feaseable in laboratories with limited resources.
Neste trabalho propusemos e analisamos metodologias empregadas no uso da tecnologia dos Ácidos Nucléicos Livres de Células Fetais (cffDNA = Cell Free Fetal DNA) no diagnóstico pré-natal não invasivo (DPIN = Non-invasive Prenatal Diagnosis). Dada a modernidade das tecnologias empregadas e a sua repercussão nas famílias envolvidas, procuramos discutir algumas implicações éticas, sociais e legais. Ao contrário da crença popular de que a placenta constitui uma barreira impermeável entre mãe e filho, há tráfego bidirecional entre o feto e a mãe durante a gravidez. Vários estudos têm demonstrado que tanto células fetais intactas e ácidos nucléicos livres de células fetais (cffNA, ou seja, DNA e RNA) atravessam a placenta e circulam na corrente sanguínea materna. Identificamos quatro diferentes aplicações da tecnologia de análise do cffDNA: a) Determinação pré-natal do sexo, utilizada em gestações com risco de uma doença ligada ao sexo e realizada através da detecção do cromossomo masculino Y; b) O diagnóstico de certas doenças de gene único, normalmente através da detecção de mutação herdada paternalmente; c) Aneuploidia fetal, tal como a Síndrome de Down, onde há alterações cromossômicas; d) Detecção do tipo de sangue fetal em gestações com risco de incompatibilidade, sobretudo RhD. Para realizar este trabalho utilizamos a determinação pré-natal do sexo em 53 gestantes em diferentes períodos gestacionais. Para tal, testamos e propusemos metodologias de extração do DNA; amplificação do DNA extraído através da técnica da PCR (Polymerase Chain Reaction) e de uma nova metodologia denominada LAMP (Loop Mediated Isothermal Amplification); e a análise final dos resultados. Além disso, comparamos a eficiência da PCR e LAMP amplificando diferentes segmentos do cromossomo Y: DSY14 e TSPY. Em três casos as amostras foram descartadas porque não houve a confirmação do sexo fetal após os testes moleculares devido à perda de contato com as gestantes. Em outros dois casos os resultados apontaram para fetos masculinos, entretanto, no ultra-som eles foram confirmados como femininos, provavelmente devido a uma contaminção. No final obtivemos 28 amostras (58,33%) masculinas, com a amplificação das sequências do cromossomo Y e 20 amostras (41,67%) femininas que não amplificaram a sequência do cromossomo Y e apenas para o controle. Nossos resultados demonstraram que a amplificação por LAMP é mais eficiente que a PCR na análise de DSY14, sendo que o limite de detecção é de 10 pg e 0,1 pg, para a PCR e o LAMP, respectivamente. Concluímos que a amplificação utilizando a metodologia de LAMP é mais rápida (60 minutos) e apresenta uma alta especificidade, sensibilidade e não requer equipamentos sofisticados para reação, comparada com a técnica da PCR. Tais características viabilizam esta metodologia em laboratórios com poucos recursos.

O presente estudo foi dividido em dois experimentos, tendo como objetivo determinar a curva de excreção do cortisol fecal e sua estabilidade nas fezes perante exposição à diferentes períodos de tempo e temperatura entre as colheitas e análises, correlacionando os níveis de cortisol fecal com o pico de cortisol sanguíneo. No experimento 1, seis fêmeas mestiças (Dorper x Santa Inês) tiveram suas fezes totais colhidas durante 24 horas após a aplicação do hormônio adrenocorticotrófico (ACTH), além de colheitas de sangue realizadas antes da aplicação do ACTH, 60, 120 e 300 minutos depois; durante as quais foram atribuídos escores de reatividade para cada animal. Logo após as análises foi iniciado o experimento 2, no qual 9 cordeiros mestiços (Dorper x Santa Inês) foram submetidos a uma situação de estresse térmico durante os horários das 11 às 15 horas da tarde, tendo suas fezes colhidas às 23 horas do mesmo dia. Após a colheita, as fezes foram agrupadas e homogeneizadas em três grupos distintos, de onde retiraram-se alíquotas referentes aos tratamentos propostos: três temperaturas (15°, 25° e 35°) e quatro tempos (1, 3, 6 e 12 horas). Os dados da curva de excreção foram analisados por ANOVA, bem como pela correlação entre os valores de cortisol sanguíneo, fecal e reatividade. Para análise da estabilidade foi utilizada ANOVA multifatorial com dois fatores (temperatura e intervalo de tempo). Para avaliação das variáveis comportamentais foi realizada a transformação de escala dos dados para \"arco-seno raiz de porcentagem\", procedendo-se à análise de variância. O modelo estatístico contemplou os efeitos de dia (1, 2 e 3) com análise individual por animal. Os parâmetros de cortisol sanguíneo, frequência respiratória e temperatura retal foram analisados pelo teste t e correlação de Pearson. Todas as comparações de médias foram realizadas por teste F e teste t (PDIFF). A reatividade durante a colheita não exerceu efeito significativo sobre os valores de cortisol sanguíneo, os quais demonstraram médias maiores 60 minutos após a aplicação do ACTH e, após 300 minutos as ovelhas apresentaram níveis de cortisol considerados normais para ovinos sem estresse. Por outro lado, o pico de cortisol nas fezes foi verificado aproximadamente 10 a 12 horas após o pico de cortisol no sangue, não sendo verificadas diminuições significativas nas concentrações que indicassem o retorno aos níveis basais durante o período de 24 horas (P>0,05). Não foram observadas diferenças significativas entre os tempos e temperaturas aos quais as amostras de fezes foram submetidas (P>0,05), verificando-se uma tendência a manutenção da concentração do cortisol fecal em ovinos durante o período de 12 horas após a colheita.
This present study was divided into two experiments, aiming to determine the excretion curve of faecal cortisol and its stability over different periods of time and temperature between harvest and analyzes, correlating the fecal cortisol levels with peak blood cortisol. The project was developed in Biometeorology and Ethology Lab, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga - SP. In the first experiment, six crossbred (Dorper x Santa Inês) females sheep had their total feces collected during 24 hours after the application of adrenocorticotropic hormone (ACTH), beyond the blood samples taken before the application of ACTH, and one, two and five hours after application; in which was attributed reactivity scores to each animal. Soon after the analysis was started the second experiment, in which nine crossbred lambs (Dorper x Santa Inês) underwent a situation of thermal stress from 11 to 15 pm, and their feces were collected at 23 hours the same day. After harveting, the feces were pooled and homogenized in three different groups, where aliquots were withdrawn relating to the treatments proposed: three temperatures (15, 25 and 35°C) and four times (1, 3, 6 and 12 hours). The excretion curve data were analyzed by ANOVA, as well as the correlation between blood cortisol levels, faecal and reactivity. For stability analysis were used multifactor ANOVA with two factors (temperature and time range). To evaluate the behavioral variables was performed the transformation of the data range for \"arc sine percentage root\", proceeding to the analysis of variance. The statistical model included effects of day (1, 2 and 3) with individual analysis by animal. The blood cortisol parameters, respiratory rate and rectal temperature were analyzed by t test Pearson correlation. All comparisons of means were performed by F and t test (pdiff). The reactivity during harvest did not exert significant effect on blood cortisol levels, which showed higher averages 60 minutes after the application of ACTH, and after 300 minutes, the sheep showed cortisol levels considered normal to them, without stress. On the other hand, the peak of cortisol in the feces was observed approximately 10-12 hours after the peak of cortisol in the blood, not being observed significant decreases that indicate the return to the basal levels during the 24 hour period (P>0, 05). Were not observed no significant differences between the time and temperature in which the faecal samples were subjected (P>0.05), verifying a tendency on the maintenance of the concentration of faecal cortisol in sheep during the 12 hour period after harvest.

Com intuito de esclarecer a associação do ganho de peso do feto no ato da tosquia, fato este, que diminui a taxa de mortalidade ao nascer, utilizamos vinte e uma ovelhas da raça merino australiano, divididos em 2 grupos com 10 integrantes cada: um tosquiado (OT) aos 70 dias do período gestacional e um segundo mantido como controle (ONT). Destas fêmeas durante o período final de gestação retirou-se a placenta e o feto através do procedimento cirúrgico segundo técnica cesariana convencional. Para efeito comparativo mensurou-se inicialmente as características morfométricas da placenta e dos fetos. Como caracterização da placenta quantificamos o número de placentônios e suas medidas. As amostras de placenta foram fixadas e processadas para microscopia de luz, com inclusão em parafina. A quantificação do glicogênio foi obtida com a mensuração de 5 campos randômicos de cada lâmina produzida seqüencialmente. As análises foram realizadas por efeito comparativo de diferença de coloração por reação histoquímica de P.A.S. Para análise estatística foi utilizado o teste T normal comparativo entre médias. Os resultados macroscópicos indicaram que o tratamento da tosquia não aumentou significativamente os pesos placentários e fetais, e tão pouco as medidas referentes ao placentônio. Nas análises microscópicas, a quantidade média de glicogênio entre as áreas quantificadas no placentônio não apresentaram diferenças significativas, já no fígado na região da tríade portal e no músculo reto houve diferença entre os animais tosquiados e os não tosquiados. Com isto podemos concluir que a tosquia realizada aos 70 dias do período gestacional influência no acumulo de glicogênio no fígado e no músculo reto femural, podendo ser estes os fatos responsáveis pelo aumento do peso dos fetos ao nascer.
In order to clarify the association of weight increase of the fetus in the act of shorn, and remembered that this fact decreases the rate of mortality at birth we tested twenty Merino australian sheep. Animals were divided into 2 groups with 10 members each: shorn (OT) to 70 days of gestational period and a second kept as control (ONT). The placenta and fetus were removed by a surgical procedure of caesarean, according conventional technique. As characterization of the placenta quantification of the placentome numbers and their measures. Samples of placenta were fixed and routinely processed for the light microscopy, with inclusion in paraffin. The quantification of glycogen was obtained with the measurement of 5 fields in each slides produced sequentially. The tests were conducted by comparative effect of a difference in color between the slides and the area covered by the histochemistry PAS reaction For statistical analysis was used the T test (student) and comparison between normal averages. The macroscopic results indicated that the treatment of shorn not significantly increased the fetal and placental weights, and so little measures regarding placentomes. The microscopic analysis, shows that the average between the areas of glycogen quantified in placentome were not different (P <0.05). Already in the liver at the portal triad region and in the rectus femoris muscle were found a significant increase of glycogen deposits (P <0.05). With this results we can conclude that the shorn done at 70 days of gestational period influence on the accumulation of glycogen in the liver and muscle of the fetuses and thus increase the weight of them at birth.

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Com o objetivo de avaliar a proteína bruta fecal como indicador de consumo e digestibilidade de bovinos alimentados com pastagem nativa situada no Bioma Pampa e inclusões de azevém e avaliar a qualidade nutricional dessas pastagens foram realizados dois experimentos em gaiolas de metabolismo. No experimento I, os animais recebiam diferentes níveis de oferta de pastagem nativa onde os tratamentos consistiam em níveis de1,5 e 2,25% do peso vivo de matéria seca e um nível ad libitum, com pelo menos 20% de sobras diárias onde foram realizados seis períodos experimentais, O experimento II consistia em diferentes níveis de inclusão de azevém na dieta de bovinos alimentados com campo nativo, os tratamentos eram 33%, 66% e 100% de azevém em substituição ao campo nativo, em dois períodos experimentias. Os experimentos foram realizados em delineamento inteiramente casualizado com 3 tratamentos e 2 repetições por tratamento em cada período. Os períodos experimentais consistiram de 10 dias de adaptação e 5 dias de coletas, durante o período de coletas foram amostradas as sobras do cocho, a forragem ofertada e ainda a produção total de fezes a cada 24 horas. Realizou-se as medidas de produção fecal, concentração de componentes fecais, consumo de nutrientes e digestibilidade dos componentes da dieta. No capítulo I foram traçadas relações entre digestibilidade e a concentração da proteína bruta fecal (PBf), sendo testados dois modelos não lineares, o exponencial e o hiperbólico gerando as equações de digestibilidade da matéria orgânica(DMO) = 0,709-9,506* exp(-0,041*PBf) com R2 0,61 e DMO = 0,942-38,619/PBf (R2 0,62), respectivamente. A relação de consumo de matéria orgânica (CMO) com a quantidade de PBf, possui comportamento linear, foi então realizada a análise de stepwise para saber quais outras variávies poderiam explicar melhor o modelo junto com a PBf gerando uma equação CMO = -6724,30 + 39*PBf + 2,55*FDNf + 11591,44*DMO com R2 0,95. Determinou-se a relação da proteína bruta (PB) da dieta (g/kg MO) x PBfecal (g/kg MO), PB dieta = 1,346x - 47,63 R² = 0,931 (modelo linear). No capítulo II, foram testados dois modelos para todas as relações traçadas no experimento II, um modelo linear e um modelo quadrático, as relações foram consumo de matéria orgânica (CMO (g/UTM)) x digestibilidade da fibra em detergente neutro (DFDN), DMO x CMO (g/UTM), DMO x CMO (g/dia), consumo de folhas (g/UTM) x DMO e CMO (g/UTM) x relação proteína/energia. As relações que não foram estatisticamente significativas para nenhum modelo foram CMO (g/UTM) x relação proteína/energia e consumo de folhas (g/UTM) x DMO. Após essas relações, verificou-se que a PBf tem um bom potencial para a estimativa de consumo e a digestibilidade por bovinos alimentados com pastagens nativas ou associadas a forragem cultivada como o azevém anual, mas estes parâmetros também são afetados por diferentes variáveis.
In order to evaluate the fecal crude protein as intake and digestibility marker of cattle fed with natural pasture from Pampa Biome and annual ryegrass inclusions and evaluate the nutritional quality of these pastures it was conducted two experiments in metabolic cages. In the first experiment, the animals received different native pasture offer levels where treatments consisted of 1.5 and 2.25% of the live weight of dry matter and ad libitum with at least 20% of daily leftovers which were carried out six experimental periods. The second experiment consisted of annual ryegrass inclusion levels in the diet of cattle fed with natural pasture, the treatments were 33%, 66% and 100% of ryegrass to replace the native pasture in two experimental periods. The experiments were carried out in a completely randomized design with 3 treatments and 2 replicates per treatment in each period. The experimental period consisted of 10 days of adaptation and 5 days of collection during the period of the trough collects the forage offered have been sampled, the leftovers and also the total fecal production in each 24 hours. It was measured the fecal productions, concentration of faecal components, nutrient intake and digestibility of diet components. In the Chapter I were study the relationship between digestibility and fecal concentration of crude protein (CPf), being tested exponential and hyperbolic equations generating the digestibility of organic matter (OMD) = 0.709 - 9.506 * exp (- 0.041 * CPf) with R2 = 0.61 and OMD =0.942 - 38.619 / CPf (R2 0.62), respectively. The ratio of organic matter intake (OMI) with the amount of CPf, has a linear relation, it was then carried out stepwise analysis to find out what other variables could explain better the model along with the CPf generating a equation OMI = -6724.30 + 0,998 * CPf + 2.55 * NDFf + 11591.44 * OMD with R2= 0.95. It was determined the ratio of crude protein (CP) of the diet (g/kg of OM) x CPf (g/kg of OM), CPdiet = 1,346*CPf - 47.63 R² = 0.931 (linear model). In the Chapter II were tested two models for all relationships outlined in experiment II, a linear model and a quadratic model, relations were organic matter intake (OMI) x digestibility of neutral detergent fiber (DNDF), OMD x OMI, leaves intake x OMD and OMI x protein/energy ratio. The relationships that were not statistically significant for either model were OMI x protein/energy and leaves intake x OMD. After these relationships, it was found that the CPf has a good potential to estimate intake and digestibility in cattle fed native pastures or associated with annual ryegrass, but these parameters are also affected by different variables.

Ewes at two sites were fed to be either condition score 2 or 3 by Day 90 of pregnancy and then grazed on various levels of feed-on-offer (FOO) from Day 90 of pregnancy until weaning, to investigate whether nutrition of Merino ewes during pregnancy and lactation affected the muscle, fat and immunity to worms of their progeny. Eye muscle and fat depth at the C-site, and faecal worm egg counts (FWECs) of the progeny were measured between 7 - 27 months of age. Ewe condition score at day 90 of pregnancy did not impact largely on the eye muscle depth, fat depth or FWEC of the progeny. Increasing FOO available to ewes during the last 60 days of pregnancy and throughout lactation increased the eye muscle depth of progeny at one site and decreased the fat depth of progeny at the other site (P<0.05), but did not affect the majority of FWECs of the progeny at either site. The FWECs of the progeny were low, indicating a relatively low larval challenge, which limits the likelihood of differences in immunity to worms between the progeny being expressed. This Masters demonstrated that levels of nutrition available to Merino ewes typical of commercial grazing conditions had only small effects on the eye muscle and fat depth at the C-site, and on the faecal worm egg counts of their progeny

The purpose of this research was to examine hindlimb blood flow and oxygen supply in the late-gestation fetal lamb under normal and pathophysiological conditions. Although the carcass, or non-visceral tissue, accounts for a large proportion of fetal weight and oxygen demand, it has received little research attention. Because the hindlimb is composed of skin, bone, and skeletal muscle, it is representative of the carcass. We implanted vascular catheters in fetal lambs to permit sampling of blood entering and leaving the hindlimb, and a transit-time flow transducer on the external iliac artery to measure hindlimb blood flow. In late-gestation, there are specific patterns of electrocortical (ECoG) and electroocular activity (EoG), which are associated with episodic fetal breathing and body movements. Hindlimb blood flow tends to be higher and more variable during high voltage ECoG activity. To determine whether this is due to the increased body movements during this state, the neuromuscular blocking agents gallamine and pancuronium were administered. Mean hindlimb blood flow fell 8.3 ± 3.5% following blockade, but flow still tended to be higher during quiet sleep. As neuromuscular blockade did not appear to effect the behavioural state modulation of hindlimb blood flow, this relationship may be directly mediated by the central nervous system. The effects of hypoxemia and ischemia on hindlimb metabolism were compared. No difference was seen in the relationship between oxygen delivery and consumption or in the overall magnitude of hindlimb lactate release for the two perturbations. Thus, for similar reductions in oxygen deliver, we found no difference in hindlimb oxygen consumption or lactate production between hypoxemia and ischemia. Therefore, there is no evidence that hypoxemia is less well tolerated than hindlimb ischemia. As arginine vasopressin (AVP) has vasoconstrictor action's in the fetus and adult, the effect of exogenous AVP was examined in fetal and non-pregnant adult sheep. Both groups exhibited similar degrees of hypertension, reduced hindlimb blood flow, and increased hindlimb vascular resistance. However, heart rate declined significantly more in the adults. Therefore, there is no evidence for a greater sensitivity of fetal vascular smooth muscle to vasopressin, but the fetus does appear to be less sensitive to the negative chronotropic effects of AVP. In conclusion, our studies indicate that the hindlimb, and thus the carcass, plays a major role in the dynamic nature of the fetus under normal conditions as well as in its ability to adapt to pathophysiological situations.

Defines the sources of reproductive wastage in FecB Fec⁺ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.
Thesis (Ph.D.) -- Dept. of Obstetrics and Gynaecology; Dept. of Animal Sciences, 1994

Clinical depression is diagnosed in 10-15% of pregnancies frequently resulting in antidepressant therapy with selective serotonin reuptake inhibitors such as fluoxetine. Human studies have suggested that third trimester exposure to fluoxetine results in negative birth outcomes such as preterm delivery, low birth weight and increased admission to neonatal intensive care units. Based on these findings, we undertook an eight day maternal IV infusion of fluoxetine (FX, 98.5 µg/kg.d) in 14 chronically instrumented pregnant sheep during late gestation (125- 140 d, term = 147 d) with a control group of 15 animals receiving sterile water. In the FX group maternal and fetal plasma FX and norfluoxetine (NFX) concentrations were within the therapeutic range reported in humans. Maternal fluoxetine infusion increased plasma serotonin levels within 15 min of infusion associated with a 20% decrease in uterine artery blood flow. Both plasma serotonin levels and uterine artery blood flow returned to control values by 1 h after infusion. The transient decrease in uterine artery blood flow resulted in fetal hypoxemia during the first 24 h of infusion. Minor alterations in fetal blood gases continued throughout the eight-day infusion period. The incidences of low voltage electrocortical activity (EcoG), eye movements and fetal breathing movements were significantly reduced in the FX group while the incidence of high voltage ECoG was significantly increased during the first 6 h of maternal fluoxetine infusion. These alterations continued throughout the eight days of infusion to a lesser degree. Fetal ACTH and Cortisol plasma concentrations in the FX group increased on Infusion Days 7 and 8 more than in the control group. Late gestation infusion of fluoxetine in sheep did not alter birth weight or gestational age at delivery. In conclusions, late gestation exposure to FX in pregnant sheep transiently altered fetal blood gas status with greater effects on fetal behavioural state and neuroendocrine function. The longer term consequences of these in utero perturbations remains to be determined.

Indomethacin is currently used in the treatment of patent ductus arteriosus, preterm labour, and for polyhydramnios. In order to investigate its clearance and disposition in the chronically instrumented ovine fetus, a sensitive assay was required. The developed GC-ECD method involves the extraction of indomethacin and a-methyl indomethacin, the internal standard, from acidified plasma, urine, amniotic and tracheal fluids using a simple one-step liquid-liquid extraction procedure with ethyl acetate. The organic extract is evaporated and the residue derivatised with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA). The derivatised samples were reconstituted with toluene and aliquots of 2 jxL injected into the GC. Calibration curves were linear over the working range of 1-32 ng of indomethacin/mL with a coefficient of determination (r ) > 0.99, following extraction of 0.1 mL of plasma, and 0.1-1.0 mL of urine, amniotic and tracheal fluids. Mean recoveries from plasma and urine were 96.99 ± 9.25 % and 94.74 ± 6.75 %, respectively. The limit of quantitation is 1 ng/mL (< 10% C.V., S/N > 10).Inter- and intra-day variabilities at each concentration point were < 11 % for concentrations between 2-32 ng/mL and < 20 % at the LOQ of 1 ng/mL. Ill The mean steady state fetal femoral arterial concentration of indomethacin was 181.67 ± 45.05 ng/mL in the high dose group (n=5), and 41.29 ± 3.14 ng/mL in the low dose group (n=2). The arterio-venous concentration difference for indomethacin at apparent steady state was minimal but statistically significant, suggesting a low placental permeability to indomethacin in sheep. The fetal total body clearance was estimated to be 44.55 + 11.14 mL/min (n=7). The placental clearance of indomethacin, as determined by the Fick principle, was calculated to be 8.85 ± 0.81 mL/min/kg. The renal clearance was estimated to be 0.015 + 0.009 mL/min (n=5). Indomethacin appeared in very low concentrations in amniotic fluid and fetal urine in high dose group fetuses. It was not observed to accumulate in tracheal fluid. The drug appeared to induce lactic acidosis and a reduction in fetal urinary output in some fetuses of the high dose group.

Studies of humans and domestic animals have shown that there is a linkage between the neonatal and post-natal health of an individual and its uterine environment during gestation. However, very little information exists for sheep and there have been no studies that have directly examined the stage of gestation at which such effects could be introduced to the conceptus. In the present study, pure-breed embryos were transferred within and reciprocally between large (Suffolk: S) and small (Cheviot: C) breeds of sheep to establish different uterine environments; SinS (large control), SinC (restricted environment), CinS (luxurious environment) and CinC (small control) and their effects upon embryonic, fetal, neonatal and post-natal development and glucose metabolism of lambs were examined. By Day 19 of gestation, conceptuses (embryo and trophoblast) developing in a restricted uterine environment (SinC) were smaller (P<0.05) than in control (SinS). The head length of SinC fetuses was smaller (P<0.05) than in SinS fetuses on Day 55 of gestation and SinC lambs were lighter and smaller (P<0.05) than SinS lambs at birth. During subsequent post-natal life, there was no difference (P>0.05) in the growth rate of SinC and SinS lambs. The liveweight and body dimensions of SinC lambs were lower (P<0.05) than SinS lambs until 9 weeks and 12 weeks of age, respectively. Day 19 peri-implantation embryos and trophoblasts that developed in a luxurious environment were bigger than in control (CinC). However, CinS fetal size did not differ (P>0.05) from CinC fetuses by Day 55 of gestation. There was no difference (P>0.05) in the birthweight and body dimensions of lambs born from these two groups. Dimension of the placentas of SinC and SinS or CinS and CinC did not differ (P<0.05) during gestation or at lambing. Concentrations of ovine placental lactogen (oPL), progesterone, insulin-like growth factor-1 (IGF-1), glucose and free fatty acid (FFA) differed between uterine environments. During glucose challenge tests, there were no differences in the concentrations of glucose and insulin, between SinC and SinS female lambs, however, glucose concentrations declined more rapidly (P<0.05) in CinS than CinC female lambs at one year of age. It was concluded that restricted uterine environment affects embryonic, fetal and neonatal development of lambs, and that these effects perpetuates until at least one year of age; but there was no effect upon glucose metabolism. Conversely, a luxurious uterine environment enhances the early development of embryos but had no effects upon subsequent fetal, neonatal and post-natal development; however glucose metabolism of post-natal female lambs was improved. It appears that these effects of uterine environment were mediated through the trophoblast during the early embryonic period and via the placenta during subsequent gestation. oPL, progesterone, IGF-1, glucose and FFA were implicated in feto-maternal dialogue. These results suggest that uterine environment significantly influences the biology of young sheep with possible economic consequences.

Based on a large series of epidemiological studies, it has been proposed that exposure to an increased nutrient supply before birth increases the risk of developing obesity in postnatal life. The physiological mechanisms underlying the association between increased nutrition before birth and later obesity are, however, poorly understood. This thesis has investigated the impact of an increased fetal nutrient supply on the programming of key systems within the appetite - regulating network and / or the adipocytes before and after birth. The studies in this thesis have demonstrated that plasma concentrations of the adipostatic hormone leptin are directly related to adiposity and the size of adipose cells in fetuses of ewes fed at or above maintenance energy requirements, which suggests that leptin may act as a peripheral signal of fat mass before birth. It has also been demonstrated that the components of the central network for appetite regulation are expressed in the hypothalamus of the fetal sheep from at least 110 d gestation ( term = 150 ± 3 d gestation ), and that the expression of the appetite - regulating neuropeptides is responsive to signals of increased nutrient supply before birth. This thesis has also demonstrated that an increase in maternal nutrition in late pregnancy results in increases in both food intake and glucose concentrations in the lamb in early postnatal life and in a significant increase in subcutaneous adiposity on postnatal day 30. Importantly, increased maternal nutrition resulted in an altered relationship between signals of increased fat mass and nutrition and expression of a central appetiteinhibitory neuropeptide, CART, in the lamb hypothalamus. It was also demonstrated that there was an interaction between the prenatal and postnatal nutritional environments in the determination of lipogenesis in the early postnatal period. The findings presented in this thesis provide evidence that programmed changes to the sensitivity of the appetite - regulating neuropeptides to signals of increased adiposity and nutritional status in early postnatal life are an important part of the physiological pathway through which exposure to an increased nutrient supply before birth may lead to an increased risk of obesity in later life.
Thesis (Ph.D.)--School of Molecular and Biomedical Science, 2006.