http://hdl.handle.net/10174/295 2026-04-06T17:13:53Z http://hdl.handle.net/10174/41172 Title: Transcriptomics in Portuguese local pig breeds: an approach to explore the molecular mechanisms underlying lipid metabolism and muscle growth Authors: Albuquerque, André Abstract: This study aimed to characterize the genetic component of economically relevant production traits by exploring the transcriptomics of the dorsal subcutaneous fat (DSF) and Longissimus lumborum (LL) muscle tissues from the local Alentejano (AL) and Bísaro (BI) pig breeds using RNA-seq technology and qPCR for validation. DSF yielded 458 differently expressed genes (DEGs), with an overrepresentation of genes associated with de novo lipogenesis in AL, agreeing with its fatter profile. Meanwhile, a higher lipolytic activity in BI pigs may be mediated by the growth hormone and AMPK signalling pathways. Lower CD40 signalling in AL suggests lower insulin sensitivity due to the pro-inflammatory effect of the excessive amount of lipids. Higher levels of leptin in AL suggests that this breed has developed leptin-resistance, as previously proposed for the genetically similar Iberian pig. Furthermore, several genes that play important roles in growth were found overexpressed in BI, supporting the idea that development stimuli can occur and be regulated at a multiple tissue level. LL yielded 49 DEGs, with different signalling mechanisms for slow type myosins identified for AL (MYH7) and BI (MYH3), while no markers for fast fibre types were found differently expressed between breeds. On the other hand, the higher expression of TNNT1 in AL pigs agrees with their lower values of shear force, suggesting the rigor mortis process to occur to a less extent in this breed, causing less shortening of the myofibers, lowering the hardiness of its meat. Overexpression of MAP3K14 in AL pigs may be associated with their lower loin proportion, induced insulin resistance, and increased inflammatory response via NFkB. Finally, overexpression of RUFY1 in AL may explain their higher IMF content via higher GLUT4 recruitment and consequently higher glucose uptake that can be stored as fat. 2023-01-11T00:00:00Z http://hdl.handle.net/10174/39994 Title: Strategies to improve colostrum management and the transfer of passive immunity evaluation in dairy calves Authors: Silva, Flávio Abstract: Colostrum management is essential to ensure an adequate transfer of passive immunity (TPI) to all dairy calves. It is equally important to routinely assess TPI in order to make the necessary corrections in colostrum management and to identify animals with lower levels of passive immunity, which are consequently more susceptible and therefore require more attention. This study aims to evaluate and improve strategies related to colostrum management and TPI on dairy farms. From 2020 to 2024, data and biological material (colostrum, blood and saliva) were collected from dairy farms in the Alentejo region. This information has led to the formulation of five chapters distributed according to their general objective. Variation in colostrum quality and its determinants were evaluated on dairy farms in Alentejo, a southern region of Portugal. Colostrum quality was assessed by Brix refractometry, which served as an indicator of total protein content, and by the microbiological composition, which served as an indicator of the hygiene practices during colostrum handling. A prevalence of 28.6% of poor-quality colostrum was observed and the main contributing factors were identified. It was also found that a significant percentage of calves (43%) received colostrum of poor microbiological quality. The factors involved in TPI were investigated and predictive models were developed. To test for association with serum IgG levels, calf, calving and colostrum data were collected. A good TPI (IgG ≥ 18 g/L) was associated with the provision of colostrum based on the calf's body weight, high microbiological quality, and the intake of a second colostrum meal within the first 24 hours of life, while the first colostrum intake should occur within the first three hours of life. The hypothesis of using saliva as an alternative fluid to blood for the assessment of TPI was tested. Given the novelty of the subject and the scarcity of information available, analyses were carried out to understand the dynamics associated with the transfer of immunoglobulins from colostrum to blood and saliva. Twenty calves were monitored during the first week of life and colostrum, blood, and saliva samples were collected to determine the chemical composition of colostrum, total protein concentration, IgG, IgA, IgM and other biomarkers of immunity, stress and redox balance in blood and saliva. The results suggested the transfer of IgG, IgA and IgM from colostrum to blood and subsequently to saliva. The transfer of immune system components was shown to be important in protecting the calf against enteric disease. A positive relationship between blood and saliva was also observed, demonstrating the potential of saliva to assess TPI in newborn calves. XV The optimisation of colostrum management through digital and instrumental applications was also evaluated. A predictive model for calf weight based on biometric measurements was developed and a web application was designed for easy application of the model. In addition, a digital Brix refractometer was tested to estimate colostrum quality at farm level, measured by several parameters and a tool to evaluate colostrum management was proposed. The calf body weight prediction model showed a high level of confidence (R2 = 0.96). The refractometer showed a high level of confidence in identifying colostrum of high-quality. In conclusion, significant advances were made to improve some of the strategies related to colostrum management. In addition, this study demonstrated the potential of saliva to assess the immune system of newborn calves, providing a non-invasive and easily to collect method that benefits both animal welfare and farm management. 2025-07-02T23:00:00Z http://hdl.handle.net/10174/39556 Title: Analytical Approaches for the Quality and Food Safety Assessment of Olive Oil: Volatile Organic Compounds Profiles, Antioxidants and Phthalates Content Monitoring Authors: Freitas, Flávia Abstract: In the plant kingdom, many fruits and seeds provide edible oils. However, olive oil, often referred to as "liquid gold", is the most important and widely used in the Mediterranean diet. Its nutritional value is considered to be twice that of cereals and ten times greater than that of wine. It is estimated that approximately 3 million tons of olive oil are consumed world wide every year. This doctoral thesis focused on the study of olive oil, addressing three main themes aimed at deepening the understanding of this food matrix, from its chemical composition to the factors affecting its quality and safety. The first theme investigated the evolution of volatile organic compounds throughout the shelf life of olive oil, focusing on markers associated with positive attributes and sensory defects. A robust method was developed using solid-phase microextraction in headspace mode (HS-SPME), coupled with gas chromatography and mass spectrometry (GC/MS). This method allowed the identification of significant variations in the levels of volatile organic compounds (VOCs), particularly those derived from the lipoxygenase (LOX) pathway, over time. Principal component analysis (PCA) revealed a clear distinction between the volatile profiles of extra virgin olive oils and deteriorated oils. The relationship between E-2-hexenal and acetic acid proved to be a potential indicator for predicting the sensory disqualification of olive oil based on the evolution of volatile compounds during storage. The second theme explored the potential of olive oil as a nutraceutical product, emphasizing the antioxidants hydroxytyrosol and tyrosol, both recognized for their health-promoting properties. A method was developed to efficiently extract these compounds from the by-products of olive oil production. These compounds were concentrated and added to the final olive oil, resulting in enriched olive oil and a concentrated antioxidant extract with functional applications. The third theme focused on the presence of plasticizers in olive oil, aiming to identify and quantify phthalate esters. Through a critical review, various analytical methods used for quantifying phthalates in olive oils and wines were evaluated, discussing analytical challenges and mitigation strategies. Additionally, a study was conducted to monitor contamination by plasticizers, including 23 phthalates and 9 phthalate substitutes, throughout the olive oil production and storage process. Using liquid-liquid extraction with hexane/methanol and analysis by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS), with detection limits ranging from 0.001 to 0.103 mg/kg, it was observed that plasticizer levels progressively increased as olive oil went through production stages. The main sources of contamination were identified, highlighting the importance of minimizing plastic use along the production line and during storage. Diisononyl phthalate (DINP) was the most prevalent compound, found at concentrations exceeding the migration limits established by the European Union in some olive oil. 2025-01-01T00:00:00Z http://hdl.handle.net/10174/17962 Title: MODELAÇÃO GEOGRÁFICA EM PROCESSOS DE CARACTERIZAÇÃO E AVALIAÇÃO DA PAISAGEM NUMA PERSPETIVA TRANSFRONTEIRIÇA Authors: Batista, Teresa Abstract: A presente dissertação intitulada “Modelação geográfica em processos de caracterização e avaliação da paisagem numa perspectiva transfronteiriça” tem como objectivo o desenvolvimento de metodologias e abordagens na análise da estrutura da paisagem e da sua relação com as funções ecológicas da paisagem. Explora-se o detalhe cartográfico e temático da cartografia de ocupação e uso do solo resultante da aplicação da legenda hierárquica Corine Land Cover (CLC) Nível 5 (Guiomar et al. 2009, Batista 2011), e a cartografia CLC2006, para a definição de unidades locais e regionais de paisagem. Analisa-se o comportamento das métricas de paisagem nos seus diferentes níveis de organização hierárquica: CLC N2, CLC N3, CLC N4 e CLC N5 e testam-se métodos para a utilização de métricas como classificadores de unidades de paisagem, nomeadamente testando o seu comportamento na cartografia de ocupação e uso do solo e das unidades locais e regionais de paisagem. Propõe-se a integração da componente tridimensional no cálculo das métricas de paisagem e ensaia-se a relação entre as métricas de paisagem e funções da paisagem. É também apresentado um conjunto de ensaios em torno da consistência das métricas de paisagem aplicadas em paisagens reais no Alentejo Central e zona transfronteiriça Alentejo, Centro (Portugal) e Extremadura (Espanha). Dos resultados obtidos ressaltam as vantagens das novas abordagens na avaliação das características estruturais e funcionais da paisagem independentemente da área e escala de observação. 2014-07-17T23:00:00Z