<p><i>In utero </i>heat stress (<b>IUHS</b>) is a major concern for realizing full production potential in the swine industry. Postnatal phenotypes, such as growth performance, post-absorptive metabolism, and stress response, are negatively altered in pig offspring that have been exposed to IUHS. With current trends in global temperatures predicting a continuation of increased temperatures, it is necessary to further investigate mechanisms driving these altered postnatal phenotypes and to find mitigation strategies to combat the negative effects of IUHS. In a first study, postnatal consequences of IUHS in pigs were evaluated and a mitigation strategy was tested. A second study was conducted to investigate the HPA axis response to a stress challenge in IUHS pigs. The first study found decreased average daily gain in IUHS pigs, and that providing a nutrient-dense diet did not rescue this lost productivity due to a decrease in feed intake for this diet. These results show the importance of maintaining beneficial gestation environments to avoid IUHS and the need to continue looking for alternative strategies to mitigate negative effects of IUHS. In the second study, IUHS pigs had a decreased change in cortisol response (<b>Δ CORT</b>) from baseline when subjected to a corticotropin-releasing hormone (<b>CRH</b>) challenge at 10 wk of age, and 15 wk old pigs had a decreased Δ CORT response when subjected to a dexamethasone suppression test and a CRH challenge as well as decreased glucocorticoid receptor expression in both the hypothalamus and anterior pituitary when compared to 10 wk old pigs. These results show changes in HPA axis function as young pigs mature and that particular focus may need to be put on IUHS pigs at a young age when they might be more vulnerable to negative impacts of stress. Overall, these studies show that IUHS causes a variety of negative postnatal effects in offspring and that a better understanding of mechanisms driving these changes along with developing alternative strategies to combat the incidence of these negative postnatal effects remains of paramount importance for the swine industry.</p>

Foram utilizadas 24 ovelhas da raça Santa Inês para coleta de tecido adiposo, sendo 16 lactantes e 8 secas. Oito ovelhas lactantes foram tratadas in vivo com bST (160 mg, em duas doses em intervalo de 14 dias) iniciando a injeção subcutânea de hormônio no 13 o dia de lactação, sendo que os animais restantes receberam somente vitamina E. Outros 8 animais encontravam-se em período seco, para que fosse verificada também a diferença das taxas lipolíticas em diferentes estados fisiológicos. Foi verificada a hipótese de que ocorra uma atuação da ST através de mudança na resposta do sistema antilipolítico da proteína Gi ligada a receptores da adenosina. O tratamento com ST exógena aumentou o ganho de peso das ovelhas lactantes (P<0,05) e também o peso dos cordeiros oriundos do grupo tratado ao final do período experimental, no entanto, não foi verificado aumento na produção de leite. As concentrações de AGNE diminuíram no decorrer da lactação para os dois grupos de ovelhas lactantes, chegando no 36 º dia de lactação a concentrações similares ao do grupo de ovelhas secas. A concentração de IGF-I sérico das ovelhas aumentou após tratamento com bST, sendo 8 dias após a segunda dose do hormônio (36 dias de lactação) superior à concentração observada para ovelhas secas. A lactação não teve influência na lipólise basal entre os diferentes estados fisiológicos. Houve um aumento significativo (P<0,01) da taxa lipolítica do tecido adiposo quando estimulada por b adrenérgico (ISO) para animais em quaisquer dos estados fisiológicos. Todavia, a taxa estimulada por ISO foi significativamente (P<0,01) mais elevada no tecido das ovelhas tratadas com bST. Na presença de ADA, ocorreu um aumento da taxa em relação à basal, mas não ultrapassou àquela estimulada por isoproterenol. O estímulo lipolítico pela eliminação de adenosina no meio através da ADA apresentou-se significativamente (P<0,01) mais elevado para ovelhas lactantes, sendo este efeito amenizado pelo tratamento com bST. O uso do análogo da adenosina PIA quando colocado no meio de cultura do tecido que foi tratado in vivo com bST teve seu efeito diminuído. Os resultados indicam um aumento da taxa lipolítica em resposta a agonista b-adrenérgico no tecido adiposo do omento de ovelhas lactantes tratadas com bST in vivo, bem como confirmam a hipótese de diminuição da ação inibitória da adenosina na cascata lipolítica naquele tecido. / Bovine somatotropin (bST) treatment in vivo alters adipose tissue metabolism by enhancing lipolytic response to adrenergic agonists. We examined the impact of bST and lactation on basal and stimulated lipolytic rates with isoproterenol (ISO; 10 -5 nM), adenosine deaminase (ADA; 0.75 U/mL), ISO plus ADA in short-term (2h) incubations of ovine adipose tissue. The anti-lipolytic effect of phenylisopropyladenosine (PIA; non-hydrolyzable adenosine analog) was evaluated at various concentrations (0.5, 1.5, 3, 100 nM). Sixteen lactating Santa Ines ewes were randomly assigned to two groups. They received two s.c. injections, with a 14 day interval, starting at d 13 postpartum with either bST (160 mg) or Vitamin E (control). Eight similar nonlactating ewes received vitamin E. Omental adipose tissue biopsies were taken on d 8 after the second bST or vitamin injection. The performance of weight and milk production were taken. The serum IGF-I was analyzed. The lipolytic rate was determined by NEFA release in serum and media as mEq of oleic acid.2h -1 g -1 tissue. Basal lipolytic rates did not change with lactation or with bST treatment in vivo (P>0,05). ISO stimulated lipolytic rate increased compared to basal and was higher for the adipose tissue from lactating ewes treated with bST (P<0,01).The lipolytic rate for adipose incubated with ADA was higher than basal for lactating ewes, with the greater response for the control. The ADA treated tissue from lactating ewes receiving bST showed intermediate lipolytic rates. Maximum lipolytic rate with ISO+ADA was also higher for lactating ewes treated with bST (P<0.01), and there was no difference between lactating and nonlactating ewes. The PIA effects were evaluated by the inhibition of ISO+ADA lipolysis, and adipose tissue from lactating ewes treated with bST showed a reduced response to PIA. The results demonstrate that in vivo somatotropin treatment increases maximal lipolytic rates stimulated by adrenergic agonist and decreases the antilipolytic effect of PIA in omental adipose tissue in ewes.

O trabalho tem como objetivo avaliar o perfil morfométrico e o metabolismo post mortem de bovinos Nelore com diferentes taxas de crescimento da desmama ao sobreano. Foram confinados 154 bovinos Nelore, machos não-castrados, com idade média de 18 meses e 350 kg de peso vivo. Os animais foram designados a um delineamento inteiramente casualizado com dois tratamentos (alta taxa de crescimento [ATC] e baixa taxa de crescimento [BTC] da desmama ao sobreano). Foram selecionados cinco animais extremos de ATC e cinco extremos de BTC (10 animais de cada ano) para realização das analises de cor (L*, a*, e b*), força de cisalhamento, perdas por cocção, e também analise do perfil morfométrico muscular. Amostras também foram coletadas para simulação da glicólise in vitro para a determinação de pH, glicose, glicose-6-fosfato e glicogênio nos pontos 0, 0,5, 2, 4, 8, 12 e 24 horas. Os dados foram analisados utilizando o software SAS 9.4. Não houve efeito da taxa de crescimento sobre as características de desempenho, carcaça nem qualidade de carne. Animais BTC apresentaram maior frequência de fibras do tipo I, enquanto animais ATC apresentaram frequência de fibras tipo IIa 4% maior. Em relação à área transversal das fibras musculares, fibras do tipo I provenientes de animais ATC foram 17% maiores. Os animais ATC apresentaram maior concentração de glicogênio nos pontos 0 e 8 horas. Os animais BTC apresentaram maiores concentrações de G6P nos postos 2 e 8 horas. Animais BTC apresentaram maiores concentrações de glicose nos pontos 8 e 24 horas. Em conclusão, a seleção de bovinos com alta taxa de crescimento no período da desmama ao sobreano promove um perfil de fibras mais glicolítico. Entretanto, essa mudança no perfil morfométrico não altera a queda do pH nem a qualidade da carne. / The objective of this study was to evaluate the morphometric profile and the postmortem metabolism of Nellore cattle with different growth rates from weaning to yearling. 154 non castrated Nellore males with 18 mo/old and 350 kg live weight were confined. The animals were assigned to a completely randomized design with two treatments (high growth rate [ATC] and low growth rate [BTC] from weaning to yearling). Five animals from ATC group and five animals from BTC group (10 animal each year) were selected. Analysis of color (L*, a*, and b*), shear force, morphometric profile, simulation of in vitro glycolysis for the determination of pH, glucose, glucose-6-phosphate and glycogen in 0, 0,5, 2, 4, 8, 12 e 24h were performed. The data were analyzed using SAS 9.4 software. There was no effect of growth rate on performance, carcass or meat quality characteristics. BTC Animals had a higher frequency of type I fibers, while ATC animals presented a 4% greater frequency of type IIa fibers. Regarding the cross-sectional area of muscle fibers, Type I fibers from ATC animals were 17% larger. ATC animals showed higher glycogen concentration at 0 h and 8 h. BTC animals had higher concentrations of G6P at 2h and 8h. BTC animals presented higher glucose concentrations at 8 h and 24 h. In conclusion, the selection of cattle with a high growth rate from weaning to yearling leads to a more glycolytic fiber profile. However, this change in the morphometric profile neither alters the pH drop nor the meat quality.

O trabalho tem como objetivo avaliar o perfil morfométrico e o metabolismo post mortem de bovinos Nelore com diferentes taxas de crescimento da desmama ao sobreano. Foram confinados 154 bovinos Nelore, machos não-castrados, com idade média de 18 meses e 350 kg de peso vivo. Os animais foram designados a um delineamento inteiramente casualizado com dois tratamentos (alta taxa de crescimento [ATC] e baixa taxa de crescimento [BTC] da desmama ao sobreano). Foram selecionados cinco animais extremos de ATC e cinco extremos de BTC (10 animais de cada ano) para realização das analises de cor (L*, a*, e b*), força de cisalhamento, perdas por cocção, e também analise do perfil morfométrico muscular. Amostras também foram coletadas para simulação da glicólise in vitro para a determinação de pH, glicose, glicose-6-fosfato e glicogênio nos pontos 0, 0,5, 2, 4, 8, 12 e 24 horas. Os dados foram analisados utilizando o software SAS 9.4. Não houve efeito da taxa de crescimento sobre as características de desempenho, carcaça nem qualidade de carne. Animais BTC apresentaram maior frequência de fibras do tipo I, enquanto animais ATC apresentaram frequência de fibras tipo IIa 4% maior. Em relação à área transversal das fibras musculares, fibras do tipo I provenientes de animais ATC foram 17% maiores. Os animais ATC apresentaram maior concentração de glicogênio nos pontos 0 e 8 horas. Os animais BTC apresentaram maiores concentrações de G6P nos postos 2 e 8 horas. Animais BTC apresentaram maiores concentrações de glicose nos pontos 8 e 24 horas. Em conclusão, a seleção de bovinos com alta taxa de crescimento no período da desmama ao sobreano promove um perfil de fibras mais glicolítico. Entretanto, essa mudança no perfil morfométrico não altera a queda do pH nem a qualidade da carne. / The objective of this study was to evaluate the morphometric profile and the postmortem metabolism of Nellore cattle with different growth rates from weaning to yearling. 154 non castrated Nellore males with 18 mo/old and 350 kg live weight were confined. The animals were assigned to a completely randomized design with two treatments (high growth rate [ATC] and low growth rate [BTC] from weaning to yearling). Five animals from ATC group and five animals from BTC group (10 animal each year) were selected. Analysis of color (L*, a*, and b*), shear force, morphometric profile, simulation of in vitro glycolysis for the determination of pH, glucose, glucose-6-phosphate and glycogen in 0, 0,5, 2, 4, 8, 12 e 24h were performed. The data were analyzed using SAS 9.4 software. There was no effect of growth rate on performance, carcass or meat quality characteristics. BTC Animals had a higher frequency of type I fibers, while ATC animals presented a 4% greater frequency of type IIa fibers. Regarding the cross-sectional area of muscle fibers, Type I fibers from ATC animals were 17% larger. ATC animals showed higher glycogen concentration at 0 h and 8 h. BTC animals had higher concentrations of G6P at 2h and 8h. BTC animals presented higher glucose concentrations at 8 h and 24 h. In conclusion, the selection of cattle with a high growth rate from weaning to yearling leads to a more glycolytic fiber profile. However, this change in the morphometric profile neither alters the pH drop nor the meat quality.

No description available.

No description available.

This thesis investigates the analysis of the extended model of animal growth proposed by Oliviera et al (personal communication, July 2009). This mechanistic model of animal growth based on a detailed representation of energy dynamics focussing on the interaction between four compartment of body composition; nutrient level, fat content, visceral protein and non-visceral protein. The model is mathematically analysed and the behaviour of the model for different feeding level is examined. The animal growth model exhibits thresholds typical of nonlinear systems and multiple stable steady states which have distinct basins of stability which depend on the value of the large number of physiologically-determined parameters. These have not been previously explored theoretically and these are done in this thesis. The model demonstrates richer behaviour where path-following techniques are used to explore the distribution in parameter space of the varying phenomenology.

No description available.

No description available.

Made available in DSpace on 2014-10-09T12:55:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:55Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP