As exigências das condições higiênico-sanitárias na produção de animais de interesse zootécnico vêm aumentando progressivamente dada à necessidade de aliar-se produtividade a produtos de alta qualidade para atender a mercados consumidores cada vez mais exigentes. Nesse sentido, a utilização de antimicrobianos, tanto na profilaxia como na terapêutica, permanece como estratégia de controle para vários microrganismos patogênicos, de importância não apenas para a produção animal como também para a saúde humana, ainda que restrições ao uso indiscriminado desses produtos têm se intensificado. Não obstante, o uso excessivo desses produtos está associado à seleção de microrganismos resistentes nas áreas de produção. Por outro lado, investigações sobre circulação de cepas resistentes em rebanhos animais, até então restritas a populações humanas, ainda permanecem limitadas no Brasil. Bactérias do gênero Enterococcus, integrantes usuais da microbiota gastrointestinal animal e humana, são indicadoras ambientais de contaminação fecal e tem-se tornado objeto de preocupação em saúde pública e veterinária dada a ocorrência de cepas resistentes à vancomicina (VRE). O presente trabalho teve como objetivo isolar, quantificar e caracterizar VRE presentes em amostras fecais de ovinos oriundos de pequenas propriedades das regiões centro-leste e nordeste do estado de São Paulo. Para tanto, 132 amostras fecais foram coletadas diretamente do reto dos animais ou do piso das instalações. As amostras foram semeadas em ágar m-Enterococcus e subcultivadas em Ágar Bile Esculina acrescido de 6 µg/mL de vancomicina (ABEV), para confirmação de Enterococcus spp e detecção de cepas resistentes. Procedeu-se igualmente a observação da morfologia, características tintoriais, bioquímicas e moleculares. O número máximo de Enterococcus spp. encontrado foi de 2,6 × 105 e 1,70 × 105 UFC/g de fezes do ambiente e dos animais, respectivamente. Na caracterização bioquímica espécies mais prevalentes foram: Enterococcus faecalis e Vagococcus fluvialis. No ABEV, houve crescimento de colônias VRE em 33 das 84 amostras de ovinos-caprinos e em 21 das 48 amostras ambientais, representando, respectivamente 46,7% e 29,3% das amostras analisadas. A análise por multiplex PCR das 54 cepas VRE obtidas indicaram que 23 (43%), 22 (41%), 2 (3,5%) e 2 (3,5%) foram positivas, respectivamente, para os genes vanC2/C3, vanC1, vanA e vanB, sendo que para 5,3% dos isolados nenhum produto foi amplificado, sugerindo a possível ocorrência de genes dos demais grupos van conhecidos entre os isolados. Os resultados obtidos indicam, de forma inédita no país, a circulação de VRE em propriedades produtoras de ovinos e caprinos, sem ocorrência de manifestações clínicas aparentes nos animais, porém com possíveis riscos à saúde dos produtores e profissionais envolvidos, bem como a eventuais consumidores. / Demands for sanitary conditions in animal farming have been increasing progressively given the need to combine productivity and high quality products to support increasingly demanding consumer markets. In this context, antimicrobial drugs used in prevention as well as in therapy remain as the control strategy for several pathogenic microorganisms, not important only in animal production but also in human health, although restrictions for the indiscriminate use of these drugs have been intensified. However, the excessive use of these products has been associated to the selection of resistant microorganisms in production areas. On the other hand, investigation on strains of public health importance circulating in animal herds is still limited in Brazil. Enterococcus genus bacteria, usually present in animal and human gastrointestinal microbiota, are environmental indicators of fecal contamination and have become a concerning subject in public and veterinary health given the occurrence of strains resistant to vancomycin (VRE). The present study aimed to isolate, quantify and characterize VRE present in stool samples of sheep and goats from several farms in the center-east and northeast regions of São Paulo State. Swabs collected one hundred and thirty-two stool samples either directly from the animal\'s rectum or from the ground. Samples were plated onto m-Enterococcus agar plates and subcultivated in Bile esculin agar with 6 µg/mL of vancomycin (BEAV) to confirm Enterococcus spp and detect resistant samples. Colonies were identified by colonial morphology, Gram\'s staining, biochemical, and molecular profile. The highest colony count was equal to 2.6 × 105 and 1.7 × 105 CFU/g of feces from environmental and animal samples, respectively. Regarding biochemical characterization, Enterococcus faecalis e Vagococcus fluvialis were the most prevalent species. VRE was detected on BEAV in 33 out of 84 sheep-goat samples and in 21 out of 48 ambient samples, indicating a positivity rate of 46.7% and 29.3% respectively in the investigated samples. Analysis by multiplex PCR of the obtained 54 VRE strains indicated that 23 (43%), 22 (41%) 2 (3.5%) and 2 (3.5%) were positive, respectively, for the vanC2/C3, vanC1, vanA and vanB genes, and no product was amplified for 5.3% of the isolates, suggesting the possible occurrence of other known van gene groups among the isolates. The results obtained in this study indicate, for the first time in the studied areas, the circulation of VRE in sheep and goat farms, with no occurrence of apparent clinical signs in the animals, but with possible health risks to the farmers and workers involved, as well as potential consumers.

As redes de sensores sem fio, aplicadas à automação do controle de ambientes representam um paradigma emergente da computação, onde múltiplos nós providos de sensores, sistemas computacionais autônomos e capacidade de comunicação sem fio, conformam uma rede cuja topologia altamente dinâmica permite adquirir informações sobre sistemas complexos sendo monitorados. Um dos fatores essenciais para obter um ganho na produtividade avícola é o controle da ambiência animal. Atualmente os métodos utilizados para o monitoramento e controle ambiental não podem considerar a grande quantidade de microambientes internos nos ambientes de produção animal e também requerem infraestruturas cabeadas complexas. Dentro desse contexto o objetivo deste trabalho foi desenvolver e testar um sistema automatizado de controle ambiental, através da utilização de sensores sem fio, que auxilie e proporcione maior segurança no controle de ambientes automatizados. O sistema monitora variáveis que influenciam na produtividade de aves, tais como temperatura e umidade e outras variáveis físico-químicas do aviário. A infraestrutura desenvolvida foi testada em um aviário experimental e resultou em um sistema seguro e com grande escalabilidade, que é capaz de controlar e monitorar o ambiente e ainda coletar e gravar dados. Foi utilizado o protocolo ZigBee® para gerenciar o fluxo de dados do sistema. Foram feitas análises da eficiência de comunicação do sistema no aviário, monitorando os pacotes de dados perdidos. Os testes demonstraram uma perda de dados de aproximadamente 2% dos pacotes enviados, demonstrando a eficiência das redes ZigBee® para gerenciar o fluxo de dados no interior do aviário. Desta forma, pode-se concluir que é possível e viável a implantação de uma rede ZigBee®, para automatizar ambientes de produção animal com coleta de dados em tempo real, utilizando um sistema integrado via internet, que compreende: instrumentação eletrônica, comunicação sem fio e engenharia de software\". / Wireless sensor networks, applied to automation environments control represent an emerging computing paradigm where multiple nodes equipped with sensors, autonomous computing systems and wireless communication capability, make up a network with a highly dynamic topology allows acquiring information systems complex being monitored. One of the key factors for a gain in the poultry productivity is the control of animal ambience. Currently the methods used for environmental monitoring and control may pass large amount of internal microenvironments in animal production environments and also require complex wired infrastructure. In this context the aim of this study was to develop and test an automated environmental control through the use of wireless sensors that assist and provide greater security in the control of automated environments. The system monitors variables that influence the productivity of birds, such as temperature, humidity and other physical and chemical variables of the aviary. The developed infrastructure was tested in an experimental avian and resulted in a secure and highly scalable system, which is able to control and monitor the environment and still collect and record data. The ZigBee® protocol was used to manage the system data flow. Communication efficiency analyzes were made in the aviary, monitoring the lost data packets. Tests have shown a data loss of around 2% of the packets sent demonstrating the efficiency of ZigBee® networks to manage the data flow within an avian. Thus, one can conclude that it is possible and feasible the implementation of a ZigBee® network to automate animal production environment with real-time data collection using an integrated internet system, comprising: electronic instrumentation, wireless communication and Software Engineering\".

Orientador: Marcos Nogueira Eberlin / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T00:54:45Z (GMT). No. of bitstreams: 1 Sanvido_GustavoBraga_D.pdf: 4476411 bytes, checksum: a0dd09e383cad0e4a59a706fee40bae6 (MD5) Previous issue date: 2012 / Resumo: O Brasil é hoje um dos maiores produtores de alimentos de origem animal. Este papel de destaque só foi alcançado a partir de grandes investimentos em biotecnologia e tecnologia. O primeiro foi responsável pelo grande aumento na produtividade dos agropecuaristas nacionais possibilitando um ganho genético de nossos rebanhos e por consequência uma maior competitividade no mercado internacional. Já o ganho tecnológico tem nos levado a melhorar nosso processamento de alimentos garantindo uma maior qualidade de nossos alimentos e fazendo com que possamos deixar de ser um país exportador unicamente de matéria-prima para nos tornarmos, cada vez mais, exportadores de manufaturas. Neste trabalho foi proposto o uso da espectrometria de massas, técnica ainda muito pouco conhecida na área de produção de alimentos, em diferentes pontos desta cadeia produtiva de alimentos de origem animal. Para a análise de embriões foi utilizado o MALDI-Q-TOF. Está técnica possibilitou a identificação do perfil lipídico de cada amostra se mostrando muito mais apta do que a técnica comumente utilizada para estas análises (GC) para a identificação de diferenças individuais. A tipificação e o monitoramento de algumas mudanças neste perfil durante as fases de desenvolvimento se mostraram intrínsecas as espécies e relacionadas ao ambiente. Esta estratégia em MALDI-MS permitiu a caracterização do perfil lipídico de embriões e oócitos de diversas espécies, contribuindo para os campos de pesquisa em reprodução tais como a das alterações do perfil lipídico nas células durante o desenvolvimento embrionário e seu papel na criopreservação de embriões in vitro. Na área de alimentos dois trabalhos foram realizados. No primeiro a detecção de maltodextrina em leite em pó foi avaliada através da técnica de fingerprinting. O eletrospray (ESI) foi utilizado para a identificação da adição de maltodextrina em leite em pó de uma forma rápida direta e simples. Este método se mostrou sensível, robusto e altamente seletivo e confiável, como foi comprovado pelos ensaios de digestão enzimática. O segundo trabalho desta área de alimentos utilizou a técnica de fingerprint por MALDI-Q-TOF para detectar a adição de gordura exógena em leite em pó bovino. Através desta técnica conseguiu-se detectar, com precisão a adição de óleo/gordura exógena em leite em pó, utilizando um procedimento simples e rápido. Este procedimento proporcionou um método robusto e seletivo para a classificação e o controle de qualidade do leite em pó. Nos últimos anos, estudos envolvendo MS tem se expandido em ritmo impressionante no campo das ciências biológicas. As novas exigências de qualidade e segurança dos mercados consumidores impulsionam a busca de métodos analíticos capazes de buscarem limites de detecção e quantificação cada vez menores. Devido a grande versatilidade da técnica de MS, foi possível, neste trabalho, o desenvolvimento de métodos analíticos em duas áreas distintas (reprodução animal e qualidade de produtos de origem animal), dentro de um mesmo tema (produção animal), com grande eficiência. Observa-se ainda que é de fundamental importância desenvolver experiência científica em grupos multidisciplinares de modo a criar competências para novos desafios e resolver problemas na área de agronegócios / Abstract: Brazil is nowadays one of the biggest producers of foods from animal origins. This prominent role in the international market was only achieved through important investments made in biotechnology and technology. The first one was responsible for the productivity increase of national agriculture producers allowing then having a genetic gain of their herds and consequently allowing them to enhancing competitiveness in the international market. The technology increase have been taking us to improve our food processing ensuring higher quality products and allowing us to become manufacture exporters instead of been just raw products exporters. In this work it was suggested the use of mass spectrometry, a still very unknown technique in the food production field, in different points of animal origin food chain. For the embryo analysis a MALDI-Q-TOF was used. This technique allowed a lipid profile identification of each single sample showing to be more able to identify individual differences than the usual techniques (GC). The typification and monitoring of some changes in these profiles occurred during development phases showed to be intrinsic to the species and related to the environment. This strategy on MALDI-MS allowed the characterization of many species embryos and oocytes lipid profiles, contributing for the fields of research in reproduction as lipid profiles changes in cells during embryo development and its role on in vitro embryo cryopreservation. In the field of food control quality two works were developed. In the first one the detection of maltodextrin in milk powder was evaluated through the mass spectrometry fingerprint technique. The ESI was used for the fast, direct and simple identification of maltodextrin addition in milk powder. This method showed to be sensible, robust and highly selective and reliable, as it was proved by the enzymatic assays. The second work in the food control quality field used the MALDI-Q-TOF fingerprint technique to detect the exogenous fat addition in bovine milk powder. Through this technique we managed to precisely detect the addition of exogenous oil/fat in milk powder, through a fast and easy procedure. This procedure provided a robust and selective method to classification and control quality of milk powder. During the last years studies involving MS have been expanding in an impressive rate in the biological sciences field. The new requisites of quality and safety of consumer markets drive to the search of analytical methods able to seek lower detection and quantification limits. Due to the great versatility of MS technique it was possible in this work to develop analytical methods in two different areas (animal reproduction and quality of animal origin products) in the same field (animal production), with great efficiency. Furthermore it is noted that it has a fundamental importance to develop scientific experience in multi-disciplinary to create competencies to face new challenges and solve problems in the agribusiness field / Doutorado / Quimica Analitica / Doutor em Ciências

Herbage and cattle production in semi-arid regions are primarily controlled by climate variation particularly rainfall variability and secondarily by disturbances such as drought, grazing and fire. These factors interact at different spatial and temporal scales in a complex manner difficult to observe or comprehend and, reduce availability and quality of herbage and cattle productivity. Variables for quantifying rangeland productivity are thus rarely available and unreliable yet options for sustainable management are limited. Grazing experiments have provided useful insight about ecological and management factors involved in rangeland functioning, but they have limited scope to deal with high environmental variation. This highlights the need for a systems approach for monitoring rangeland and cattle productivity at the appropriate spatial and temporal scales to enable productivity to be maximised whilst risk to climate variation is minimised. This study explored two broad objectives: to determine the ranch-scale impacts of rainfall variability and drought on herbaceous aboveground biomass (AGB) using optical remote sensing; and to parameterise, evaluate and apply a systems model, the Sustainable Grazing Systems (SGS) whole farm model to complement grazing experiments in assessing the effects of grazing strategies on beef cattle production. To determine rainfall variability impacts, twenty regression models were firstly developed between measured herbaceous AGB and, classical and extended multispectral vegetation indices (MVIs) derived from a Landsat 8 image. End-of-season herbaceous AGB was predicted with high accuracy (r2 range = 0.55 to 0.71; RMSE range = 840 to 1480 kgha-1). The most accurate model was used to construct a regression between rainfall and AGB derived from peak-season Landsat images available between 1992 and 2017. Standardised precipitation index and standardised anomalies of herbaceous AGB production were then used in a convergence of evidence approach to determine the response of AGB to rainfall variability and drought intensity. Total wet season rainfall revealed high variability (33 to 41 % CV) and subsequent herbaceous AGB production were 18 to 35 % more variable. Spatial heterogeneity of AGB production across herbaceous communities were high and deviated from mean AGB by 51 to 69 %. Landscape-level temporal variation of AGB production remained stable despite the increase of climate variability experienced in the region in the past 50 years. Climate inputs and parameter sets for upper-, mid- and foot- slope land types and key grass species, Urochloa mosambicensis and Eragrostis curvula were developed by integrating spatial data with previous soil surveys and extensive reviews of published experiments. A simulation experiment was conducted between 1992 and 2017 for all combinations of land types and grass species to analyse the extent of improvement resulting from parameter adjustments. The SGS model predicted the growth pattern known for grasses native to dry regions of southern Africa. The model represented measured herbaceous biomass moderately well (r2 = 0.57), at low average error (RMSE, 820 kg DM ha-1) despite huge discrepancies in summary statistics for measured (mean, 3877 kg DM ha-1) and simulated (mean, 3071 kg DM ha-1) biomass and residuals. Model predictions were also significantly correlated with remotely sensed AGB (r2 = 0.46) at reasonable overall performance error (RMSE, 981 kg DM ha-1). The integrated workflow developed for parameterising and calibrating the SGS pasture-simulation model can benefit model users in data-constrained environments. Animal growth parameters specific to Brahman weaner steers were defined in the SGS model to enable evaluation of impacts of recommended (10 haLU-1) and other three stocking rates (7, 15 and 20 haLU-1) and multi-paddock grazing systems (2-, 3- and 4- paddocks per herd) on rangeland productivity. Overall, there were no observable differences in herbage production and dry matter intake irrespective of stocking rate and multi-paddock grazing system. But stocking rate effects on animal production were more pronounced compared to multi-paddock grazing systems. To maximise cattle productivity in semi-arid rangelands, management should be emphasised on manipulation of stocking rates over multi-paddock grazing systems. Keywords Rangeland monitoring, climate risk, sustainability, animal productivity, grazing strategies / Thesis (PhD (Animal Production Management))--University of Pretoria, 2020. / National Research Foundation of South Africa / University of Pretoria Department of Research and Innovation Support / Animal and Wildlife Sciences / PhD / Unrestricted

Sustainable animal production on pasture planted on rehabilitated mine land will only be possible if the optimal stocking rate for animal and pasture production is determined. A grazing trial was conducted on tall fescue, established on rehabilitated mine land and irrigated with mine waste water. The aims of this study were to quantify: a) animal performance and nutritive value at different levels of nitrogen (N) fertilization during pasture establishment, and b) intake, animal performance (defined as average daily gain; ADG) and nutritive value when different stocking rates were applied. This study was done during two seasons: season one in winter (6 June -16 July 2008) and season two in spring (28 Aug – 6 Nov 2008). In terms of post mining land use this study supplied valuable information on potential livestock production. The higher level of N fertilization applied during the winter of 2007 at pasture establishment resulted in a significantly (P < 0.05) higher crude protein (CP) concentration a year later compared to the lower levels of N fertilization. During the winter grazing season the pasture contained an average of 83.4 g CP kg-1 dry matter (DM), 601.9 g NDF kg-1 DM, 6.2 g Ca kg-1 DM and 1.7 g P kg-1 DM, the average in vitro organic matter digestibility (IVOMD) was 642.2 g kg-1 OM and the average leaf: stem ratio was 88:12. The ADG of crossbred weaner calves grazing the low N fertilization (LN), low stocking rate (LS) paddock (229.1 g day-1) was significantly (P < 0.05) lower than the ADG of weaner calves grazing the LN, high stocking rate (HS) and the high N (HN), LS respectively. The ADG of the animals in the HN, LS paddock was 482.7 g day-1 and in the LN, HS paddock was 310.6 g day-1. The low ADG for the LS treatment was due to the low CP concentration of this paddock, with values as low as 55.1 g CP kg-1 DM recorded during the winter grazing period. Low pasture nutritive value during winter can potentially limit animal production.spring grazing season the pasture contained an average of 101.0 g CP kg-1 DM, 639.1 g NDF kg-1 DM, 8.9 g Ca kg-1 DM and 2.1 g P kg-1 DM. The average leaf: stem ratio was 85:15, IVOMD was 717.5 g kg-1 OM and effective DM degradability (in situ) was 56.1 %. The average OM digestibility estimated with the alkane method varied between 720.8 to 768.3 g kg-1 depending on the alkane used and weather a correction was made for the faecal recovery of the alkane used. On average the forage available in the paddock with the LS had a significantly (P < 0.05) higher CP concentration, leaf: stem ratio and IVOMD, with a significantly (P < 0.05) lower NDF concentration than the HS paddock. This is probably due to the fact that in the HS paddock forage with a high nutritive value was removed at a higher rate. Irrespective of the calculation used, digestibility calculated by the alkane method did not differ significantly (P > 0.05) between paddocks at any time period. The average intake in the paddock with medium grazing stocking rate (MS) was significantly (P < 0.05) higher than the average for the other paddocks. The paddock with the MS was managed to supply a pasture DM allowance of 2.5 % body weight (BW). The DM intake over the spring season was 2.2 % BW. The MS treatment supplied sufficient plant material without resulting in large accumulation of plant material. The ADG for the spring season was 110.5 g day-1 and averages for each paddock did not differ significantly (P > 0.05) from each other. During the / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

<p>  Agriculture is a growing industry, as it supplies food for the increasing world population. Additionally, career opportunities within the industry are also increasing. In Indiana agriculture in particular, the poultry industry is expanding at a high rate as poultry products are an affordable and healthy protein option for consumers. However, the industry is left with the challenge of fulfilling open job positions in order to produce more food. Due to the demographic shift from rural to urban areas, a gap between the understanding of farm to fork exists among consumers. This adds to the challenge, as interest in agriculture decreases. One way to increase consumer knowledge and interest in agriculture is through education. Limited agricultural-related curriculum exists for K-12 teachers to implement in their classrooms. By creating awareness of the agriculture industry, confidence can be instilled in students and they are more likely to find the content interesting.  This interest can impact their future career choice. Chapter two of this thesis reviews the literature in regards to the relevance of the agriculture industry, agricultural-related curriculum, learning development, and teacher impact on learning.  </p> <p>Chapters three and four of the thesis discuss two studies conducted during the implementation of an agricultural-related curriculum for elementary students. The POULT Program was created to provide elementary students with an accurate and relevant online STEM-based curriculum focused on the turkey industry. The program took place over six consecutive school days in 23 4th and 5th grade Indiana classrooms during the fall of 2021. Seventeen teachers and 482 students participated in the study. Students completed five online modules, an interactive notebook, turkey digestion simulation game, and a class project.</p> <p>Chapter three analyzes how students’ previous experience and knowledge, the POULT Program, and the taxonomy of assessment questions impacted students' interest in the turkey industry and agricultural literacy. Results from the study showed that students’ agricultural literacy increased from pre to post program completion, individual interest was predicted by previous knowledge, and individual interest had a positive impact on students’ situational interest. Students’ agriculture knowledge, turkey knowledge, and agriculture experience also impacted situational interest. With these results, we can conclude that agricultural-related curriculum can have an impact on students’ agriculture literacy and their interest in agriculture. </p> <p>Chapter four analyzes how teacher self-efficacy, previous experience, and previous knowledge impacted students’ interest in agriculture. We found that teachers reported high engagement self-efficacy and low poultry science content knowledge self-efficacy. We also found that teachers with more agriculture experience had greater motivational self-efficacy, and teachers with greater agriculture knowledge had lower motivational self-efficacy. Teachers’ instructional self-efficacy also had a positive impact on students’ challenge. Teachers reported that they liked the program content and class project. Overall, teachers reported that technology issues and time constraints were limiting factors of the program. </p> <p>In conclusion, the POULT Program was successful in increasing students’ agricultural literacy. We learned that previous knowledge and experience, teacher self-efficacy, and agricultural-related curriculum can impact students’ interest in agriculture. From these findings, we can create and effectively implement more agricultural-related curriculum that will benefit students by making them more aware of the industry and potentially impacting their future career choices. </p>

<p>The attached thesis consists of a literature review of inquiry-based learning levels and two studies examining the impact of inquiry-based learning levels on student engagement, interest, and motivation in an animal science context. </p>

<p>  </p> <p>Environmental enrichments have been investigated to determine impacts on turkey health and welfare; however, there is limited data to determine the impact of these enrichments on fresh or processed turkey meat quality. One hundred and forty-four turkeys were randomly assigned to six enrichment treatments: control (C), pecking block (PB), platform (P), platform + straw bale (PSB), straw bale (SB), and tunnel (T). Each treatment was replicated within two rooms in the same barn, with 24 pens total (n = 4 pens/treatment). At 19 weeks of age, turkeys were weighed (live weight, kg), and harvested over two days, with three birds from each pen per day (n=144). A subset of 96 turkeys were fabricated into wings, boneless thighs, drumsticks, and boneless breasts at 24 h postmortem in order to determine carcass cutting yields. From the breast and thigh, three, 1.25 cm samples were taken for pH, proximate analysis, and drip loss. From the breast, three, 2.54 cm samples were taken for instrumental color and sensory analysis, with all remaining breast sample used for further processed boneless turkey breast. Breast portions were pumped with a commercial brine (water, salt, brown sugar, sodium phosphate, sodium erythorbate, and sodium nitrite) to 110% by weight. Brined breast was then vacuum sealed and vacuum tumbled (9 rpm for 90 min, stopping every 15 min for 10 min). Tumbled breast was stuffed into a cellulose casing, thermally processed (internal temperature 68.3oC), and smoked to produce boneless turkey logs. From each log, eight, 1.25 cm slices were taken for packaged purge loss, expressed moisture, instrumental color, and texture and sensory analysis. All treatment levels were analyzed using PROC GLM (SAS 9.4, SAS Institute, Cary, NC). Statistical significance level was set at <em>P≤</em>0.05. For fresh turkey, results showed significant differences in live weight by treatment. SB turkeys weighed the least, PB turkeys weighed the most, and T, PSB, C, and P were intermediate in weight (<em>P=</em>0.008). Treatment did not impact the cut-out values for breasts (<em>P=</em>0.387), thighs (<em>P=</em>0.985), wings (<em>P=</em>0.211), and drumsticks (<em>P=</em>0.575). Treatment did not impact breast L* (<em>P=</em>0.777), a* (<em>P=</em>0.247), or b* (<em>P=</em>0.366) or thigh L* (<em>P=</em>0.936) and a* (<em>P=</em>0.067), but PSB thighs displayed the highest b* values and PB thighs displayed the lowest (<em>P=</em>0.037). Finally, for fresh turkey, treatment did not impact breast drip loss (<em>P=</em>0.766), thigh drip loss (<em>P=</em> 0.933), breast pH (<em>P=</em>0.197), or thigh pH (<em>P=</em>0.385). For processed turkey quality, treatment had no effect on a* (<em>P=</em>0.498) or b* (<em>P=</em>0.831) but was significant for L*. SB, T, P, and PSB had lighter color values, C had darker color values, and PB had intermediate values (<em>P=</em>0.024). Finally, for processed turkey quality, treatment did not impact processing yield (<em>P=</em>0.058) or packaged purge loss (<em>P=</em>0.581), but treatment impacted expressed moisture (<em>P=</em>0.041). PB, PSB, C, and T had higher expressed moisture loss, P had the lowest, and SB had intermediate expressed moisture loss (<em>P=</em>0.041).</p>

The series of experiments described in this thesis were designed to investigate the role of suckling or late weaning in the response of young lambs to nematode infection. All experiments were conducted outdoors with grazing animals and no supplementation but for suckled groups of lambs whose counterparts were weaned to ryegrass – white clover swards. The parasite of interest was mainly Teladorsagia circumcincta solely but with mixed infection of Trichostrongylus colubriformis in one instance. In Chapter 3 (first experiment), the hypothesis that milk per se may have a direct effect on nematode development, rather than an indirect effect through enhancement of host immunity by superior nutrient supply was tested. Sixty, twinborn lambs were used, allocated to one of eight groups formed by either dosing lambs from 42 days of age or not with the equivalent of 1000 or 250 L₃ T. circumcincta larvae d⁻¹ until five days before necropsy, while a twin was either weaned at 39 days of age, suckled as single or twin until necropsy on day 84. The possibility that weaning one of a twin set onto pasture in close proximity to the ewe would cause abnormal ewe and lamb behaviour was tested by replicating the work in twins maintained as twins but in which one twin received equivalent of 250 and the other 1000 L₃ T. circumcincta larvae d⁻¹. This showed no abnormal ewe nursing or lamb suckling behaviour as a result of weaning a twin in a set. Relatively low faecal egg counts (FEC) and a two to three fold lower worm burdens suggest suckling could reduce larval establishment. Inability to detect peripheral titres of immunoglobulins supports this conclusion. An intra worm-population regulation of T. circumcincta, indicated by a pattern of greater egg-laying by a numerically smaller but physiologically better developed nematode population in suckled lambs measured in eggs 'in utero' and worm length made interpretation of FEC difficult. Suckling significantly improved weight gain and carcass weights, but early weaning did not reduce resilience to infection. In Chapter 4 (second experiment), 40 pairs of twin lambs, average age of 39 days, were either infected with the equivalent of 1000 L₃ T. circumcincta larvae d⁻¹ or not, while one twin was weaned and the other allowed to continue suckling. Necropsy was carried out on groups of five and six lambs from each of the uninfected and infected treatments, respectively, at mean age of 84, 112, and on six lambs from each group at 140 days of age. This serial slaughter allowed further confirmation of the hypothesis in Chapter 3 but also investigated the long-term effect of suckling on resistance or resilience of lambs at the trial when immune responses were anticipated to be developing. An in vitro direct larval challenge (IVDC) study, to monitor larval establishment, was carried out on tissue explants from necropsied lambs. Suckled lambs consistently showed lower FEC (P < 0.05) and worm burdens (P < 0.05) at every phase of the trial. Within the infected groups, % in vitro larval rejection suggested earlier immune responses in the weaned lambs by day 84, which was not consistent with lower worm burdens in suckled lambs but appeared similar in the subsequent necropsies. Lambs continued to show better growth due to suckling while weaning did not reduce the resilience of lambs confirming observations in Chapter 3. The immunoglobulin profile suggested the commencement of immune responses in lambs from the period after the 84th day necropsy, with significantly greater (P < 0.01) IgA titre in the infected groups, and the suckled lambs towards the end of the trial on day 140. A vaccinating effect of early exposure to parasites was coincidentally revealed as a result of unintentional pasture larval contamination, seen in suckled non-infected lambs shedding fewer eggs and harbouring fewer worms during the later necropsies compared with their weaned non-infected counterparts. In Chapter 5 (third trial), 93 pairs of twin lambs, 47 pairs of which received a vaccinating mixed infection of T. circumcincta and T. colubriformis larvae (60 L₃ / kg W / d) at ratio 40:60, respectively during the period 36 – 103 days of age, were either weaned early on day 51 or later on day 108. All lambs were drenched on day 108 and groups received challenge infections from day 116, at same rate with the vaccinating infection, or not, which ceased five days before respective necropsies. Necropsies were carried out on selected lambs on days 108, 184 and 218. The direct effect of milk on larval establishment appeared to feature only in the T. circumcincta populations on slaughter day 108. The long-term benefit of late weaning for development of resistance was conditional on lambs receiving the vaccinating infection, and appeared to be more pronounced in the small intestine, reflected by a greater reduction of T. colubriformis populations in that organ than of T. circumcincta populations in the abomasum. A negative consequence of enhanced immune response was the suggestion of an increased metabolic cost in reduced performance of lambs. In conclusion, the work provides support to the hypotheses that: (a.) suckling may reduce the establishment of nematode larvae through the direct effect of milk, (b.) may enhance rapid development of host immunity to infection, and (c.) it further suggests that lack of larval experience during suckling may have long term negative implications for host resistance. Finally, it suggests that milk may play little role in the enhancement of host resilience to infection and, on the contrary, that additional metabolic cost may be associated with a more rapid development of immunity resulting from larval challenge while suckling.

The experiments described in this thesis investigated nutritional and physiological aspects of antler growth in red deer stags. The initial experiment (Section 3) examined the effects of winter nutrition on subsequent antler casting date and velvet antler weight. Mature stags on two different farm types (hill country, Farm H and irrigated lowland, Farm L) were offered three levels of winter nutrition, two levels of a concentrate supplement (ad libitum pellets and 1/2 ad libitum pellets) and a basal hay ration. On both properties liveweight gains occurred in supplemented groups and liveweight losses in unsupplemented groups. At antler casting there were significant differences in liveweight of approximately 10 kg between fully supplemented and unsupplemented groups. Realimentation of winter liveweight losses subsequently occurred so that by the following rut the effects of winter undernutrition had been eliminated. On Farm H poor winter nutrition (hay only) resulted in a significant delay in casting date (13 days) and lower velvet antler yields (0.24 kg), than in stags offered the ad libitum concentrate ration. Stags on Farm H were 13 kg lighter at commencement of the trial than at Farm L and the differences in treatment effects obtained between farms may have been due to differences in body condition at commencement of the trial. An association was demonstrated between liveweight and date of antler casting, with heavier stags casting earlier than lighter stags. There was no effect of age of stag on casting date. Of the liveweights recorded, liveweight prior to the rut showed the best relationship with casting date, possibly because the seasonal nature of liveweight change meant that a weight recorded at this time gave the best indicator of the true frame size of a stag. Both age and liveweight significantly affected velvet antler weight, with increases of velvet antler weight of 0.26 kg between 3 and 4-year-old stags and of 0.30 kg between 4 and 5-year-old stags at the same liveweight. Within an age group velvet weight increased by 0.12 kg for each 10 kg increase in pre-rut liveweight. The experiments described in Section 4 comprised studies on antler growth and composition. In order to obtain data on antler growth and composition individual antlers were removed sequentially from mature red deer stags between 28 and 112 days after casting of hard antlers. Contralateral antlers were removed after stripping of velvet. Wide variation occurred in antler casting date (53 days) compared to date of velvet stripping (24 days). The duration of the period of antler growth may therefore be governed more by date of casting than by date of velvet stripping. Mean duration of the antler growth period was 164 days. Growth in length of the antler appeared to follow a sigmoid curve. However, between 28 and 112 days after casting, rates of elongation were close to linear. Mean length of hard stripped antlers was 0.71 m and between 28 to 112 days after casting mean rate of antler elongation was 0.62 cm/day. Over this period indivdual antlers increased in fresh weight at a rate of 13.7 g/d, with heaviest weight recorded 112 days after antler casting, at approximately 130% of final hard antler weight. Between 28 and 91 days of growth, volume of blood in the antler increased linearly at a rate of 194 ml/kg. Three phases of mineralization were demonstrated in developing antlers. Tips of growing antlers were cartilaginous and poorly mineralized. A zone of mineralization occurred 5.0 to 7.5 cm behind the antler tip which corresponded histologically to the transition from mineralized cartilage to trabecular bone. The second phase of mineralization occurred through continued accretion of trabecular bone in the antler shaft. The third phase, described as "terminal mineralization" in this study, appeared to be associated with a rapid increase in density of cortical bone in the periphery of the antler shaft. Terminal mineralization (between 91 and 112 days after casting of hard antlers) coincided with the slowing of growth in length, a decrease in relative blood volume in the antler and an increase in levels of plasma testosterone. These events occurred close to the summer solstice. At velvet stripping individual antlers had a mean weight of 1.12 kg and contained 81.1% dry matter (DM). Fat free organic matter (FFOM) and ash concentration in DM were 36.6 and 60.0%, respectively. Peak daily rates of FFOM and ash deposition occurred between 91 days and 112 days after casting, at rates of 1.4% of hard antler FFOM and 1.6% of hard antler ash. For a stag producing 2.24 kg of hard antler mean rates of FFOM and ash deposition over this period were 9.3 and 18.3 g/d, respectively. On a whole antler basis calcium concentration in antler ash remained constant, at around 35%. Therefore peak rate of antler calcium deposition would be 6.4 g/d. In the final experiment (Section 5) mature stags were offered a maintenance ration of greenfeed oats during the period of peak calcium requirement for antler growth and the kinetics of calcium metabolism were examined using a radio-isotope (⁴⁵Ca). Rates of faecal endogenous loss were low and at approximately 6.4 mg/kg BW per were half the estimated requirements of ARC (1980) for sheep and cattle. Availability of calcium from greenfeed oats was low (mean, 37%) and less than 30% of total calcium requirements were derived from the diet. Poorly mineralized skeletal bones indicated that the shortfall in antler calcium was derived from the skeleton. In spite of a severely negative calcium balance stags were capable of maintaining high and apparently normal rates of antler calcium deposition (mean, 44 mg/kg BW per day). Antlers appear to be acting as a sink with calcium being irreversibly deposited in the antler and lost to the animal's body. On the assumption therefore that antler calcium behaves like calcium lost during lactation a kinetic model of calcium metabolism in the stag was developed.