Il y a actuellement une pression mondiale pour revoir les pratiques d'utilisation des antimicrobiens (UAM) en production animale afin de limiter la propagation de bactéries résistantes aux antibiotiques. Conséquemment, les Producteurs de Poulet du Canada examinent la possibilité de réduire leur UAM en supprimant les antibiotiques médicalement importants en médecine humaine (AIM) des programmes préventifs avec la mise en place de leur stratégie de réduction de l’UAM. Cependant, les informations sont rares sur les conséquences de telles approches dans un contexte canadien. L'objectif de cette thèse était d'étudier les impacts sur les performances zootechniques, le contrôle des maladies intestinales et le microbiote cécal de deux stratégies de réduction de l'UAM dans des troupeaux commerciaux de poulets de chair par rapport à une UAM conventionnelle. Sur sept fermes commerciales de poulets de chair, un poulailler a été attribué aux traitements de réduction des antibiotiques pour six troupeaux consécutifs, tandis qu'un poulailler similaire sur le même site a été alloué à l'UAM conventionnelle (CONV) pour six troupeaux consécutifs (n = 84). Les stratégies de réduction des antibiotiques consistaient en l'utilisation continue d'ionophores dans l'alimentation sans (TX1) ou avec de l'acide butyrique (TX2). Aucune différence statistique (p > 0.05) n’a été notée entre TX1, TX2 et CONV sur les performances zootechniques et la santé intestinale. Les comptes d’oocystes d’Eimeria spp. étaient significativement (p < 0.05) inférieurs entre 22 et 34 jours d'âge dans les troupeaux CONV comparé aux TX1 et TX2. Le type de programme antibiotique a eu un impact relativement mineur (valeur R = 0.039), mais statistiquement significatif (p = 0.002), sur le microbiote cécal, tandis que les facteurs environnementaux ont montré les corrélations significatives (p = 0.001) les plus fortes avec le microbiote. Parmi les composantes du microbiote cécal associées à la croissance, le gain quotidien moyen (GMQ) était significativement associé à la Richesse bactérienne (p < 0.05). L’abondance relative de la famille bactérienne Lachnospiraceae fut la mesure la plus fortement corrélée à un GMQ augmenté, tandis que l’abondance relative de nombreuses familles bactériennes, incluant les Porphyromonadaceae, les Planococcaceae et les Veillonellaceae, fut corrélée à un faible GMQ. Ces taxons défavorables formaient un vaste réseau de corrélations positives entre elles, et négativement corrélées aux Lachnospiraceae. En conclusion, ces travaux ont contribué à améliorer la résilience de l'industrie avicole en fournissant des stratégies alternatives aux AIM pour prévenir les maladies intestinales. Des connaissances importantes sur le microbiote cécal des poulets de chair furent générées et pourront considérablement influencer les directions futures de la manipulation du microbiote pour favoriser la croissance. Par exemple, un paradigme important a été remis en question en illustrant que les additifs médicamenteux dans l'alimentation n’influencent que marginalement le microbiote cécal et que ce sont plutôt des facteurs environnementaux qui sont fortement impliqués dans la formation des communautés bactériennes cécales. La clé pour développer un microbiote cécal idéal chez les poulets de chair pourrait résider dans la capacité d'influencer ces facteurs, plus particulièrement l'exposition précoce à des communautés bactériennes bénéfiques et le contrôle de la flore résidente spécifique à la ferme. / There is a global pressure to review current antimicrobial use (AMU) practices in animal production and limit large-scale propagation of antibiotic resistant microorganisms. Consequently, the Chicken Farmers of Canada are examining the possibility to responsibly reduce AMU by discontinuing medically important antibiotics (MIAs) for humans from disease prevention programs of broiler chicken flocks through the implementation of their Antimicrobial Use Reduction Strategy. However, information is sparse on the consequences of such approaches in a Canadian commercial poultry production context. The general objective of this thesis was to investigate the impacts of two strategies reducing AMU in commercial broiler chicken flocks on zootechnical performance, control of intestinal diseases and the cecal microbiota compared to conventional AMU. On seven commercial broiler chicken farms, a house was allocated to the antibiotic reduction treatments for six consecutive flocks, while a similar house on the same premises was assigned to the conventional AMU (CONV) for six consecutive flocks (n = 84). The antibiotic reduction strategies consisted of continuous in-feed ionophores without (TX1) or with butyric acid (TX2). There were no statistical differences (p > 0.05) between TX1, TX2 and CONV for zootechnical performance and intestinal health. Predicted Eimeria spp. oocysts were significantly lower (p < 0.05) between 22 to 34 days of age in CONV flocks compared to TX1 and TX2. The type of antibiotic program had a relatively minor impact (R-value = 0.039), but statistically significant (p = 0.002), on the cecal microbiota composition, while environmental factors such as the farm and flock cycle showed the strongest statistically significant (p = 0.001) correlations with the microbiota composition (R-values of 0.239 and 0.374, respectively). Amongst the cecal microbiota components associated with weight gain, the average daily gain (ADG) was significantly associated with bacterial Richness (p < 0.05). The relative abundance of the bacterial family Lachnospiraceae was the most important measure correlated with ADG, while the relative abundance of numerous bacterial families, including Porphyromonadaceae, Planococcaceae and Veillonellaceae, were correlated with decreased growth rate. These unfavourable taxa formed a large network of positive correlations, indicating potential co-occurring synergies between these undesirable taxa. This network was also negatively correlated to Lachnospiraceae. In conclusion, the findings in this work contributed to improve the sustainability of the modern poultry industry by providing feasible alternatives to the practice of using MIAs for the prevention of intestinal diseases in broiler chickens. This project also generated important knowledge on the cecal microbiota of broiler chickens that could considerably influence future directions of microbiota manipulation in a perspective of improving zootechnical performance. For instance, an important paradigm was challenged by the indication that in-feed antibiotics and prebiotics may only influence marginally the microbiota during grow-out. Rather, this work suggests environmental factors are strongly involved in shaping the bacterial communities residing in the ceca of broiler chickens. Hence, the key to successfully develop an ideal cecal microbiota in broiler chickens may reside in the ability to influence such factors, more specifically the early exposure to beneficial bacterial communities and the control of farm-specific resident flora.

Die Wasserknappheit wird aufgrund des Klimawandels voraussichtlich häufiger und intensiver auftreten, wodurch die Wasserkonkurrenz zunimmt und die Nahrungsmittelproduktion gefährdet wird. Höhere Temperaturen und längere Dürren können auch die Wasserverfügbarkeit der Tierhaltung beeinflussen. In Folge dessen kann es zu einer Verringerung des Futterangebots und damit zu einer Beeinträchtigung der Produktion kommen. Auch aus diesem Grund sind nachhaltige und resiliente Produktionssysteme erforderlich, um den Nahrungsmittelbedarf einer wachsenden Bevölkerung zu decken. Auf Pflanzenproduktion und Tierhaltung entfallen 72 % der weltweit entnommenen Wassermenge. Der Löwenanteil des Wasserbedarfs in der Tierhaltung besteht bei der Futtermittelproduktion. Weiterhin wird Wasser für die Trinkwasserbereitstellung sowie für die Reinigung und die Kühlung der Ställe benötigt. Tierproduktionssysteme müssen zukünftig mit betrieblichen Maßnahmen die Wasserressourcen besser ausnutzen. Die Steigerung der Wasserproduktivität in der Pflanzenproduktion und der Tierhaltung durch eine integrierte Bewirtschaftung und Steuerung der eingesetzten Wasserressourcen sind hierfür von entscheidender Bedeutung. Die Wasserproduktivität beschreibt das Verhältnis von Output zu Input: das Verhältnis von Output (z. B. kg Milch) zu produktivem Wasserinput (z. B. m³ Transpiration). Das Wasserinput umfasst den direkten Wassereinsatz und den indirekten Wassereinsatz, z.B. für zugekaufte Futtermittel. Die Ermittlung der Wasserproduktivität wird vor allem bei der Bewertung von landwirtschaftlichen Maßnahmen zur Verbesserung des Niederschlags- und technischen Wassereinsatzes in der Tier- und Pflanzenproduktion benötigt. Zur Steigerung der Wasserproduktivität und auch um die Umweltwirkungen der Tierhaltungssysteme zu verringern, bedarf es einheitlicher Methoden. Im Jahr 2019 hat die Food and Agriculture Organization of the United Nations (FAO) mit dem Livestock Environmental Assessment and Performance (LEAP) Partnership Richtlinien für die Bewertung der Wassernutzung in Tierproduktionssystemen und zugehöriger Lieferketten veröffentlicht. Zielsetzung ist die Ermittlung der Wasserflüsse auf betrieblicher Ebene, um einerseits die Wasserproduktivität zu ermitteln und andererseits den Beitrag der Tierhaltung zu einer möglichen Wasserknappheit zu bewerten. In dieser kumulativen Dissertationen werden die Ergebnisse der ersten Anwendung dieser Leitlinien der FAO in landwirtschaftliche Betriebe in Brasilien vorgestellt. In referierten Fachzeitschriften wurden bereits drei Originalarbeiten veröffentlicht. Im Rahmen der drei Veröffentlichungen wurde die Wasserproduktivität wurde für 115 Betriebe (Schweine-, Geflügel- und Milchviehbetriebe) im Einzugsgebiet des Lajeado Tacongava in Südbrasilien berechnet, wobei die Auswirkungen der Viehzucht auf die Wasserknappheit bewertet wurden. Die Ergebnisse der ersten und zweiten bereits veröffentlichten Originalarbeiten zeigen den großen Einfluss von Futtermitteln auf die Wasserproduktivität tierischer Erzeugnisse. Die Ergebnisse unterstreichen daher die Notwendigkeit einer engen Zusammenarbeit zwischen Pflanzenproduktion und Tierhaltung. Die Niederschlagswasserproduktivität der Futterproduktion muss verbessert werden, um das Management der Tierernährung zu optimieren. Darüber kann eine höhere Wasserproduktivität der Tierhaltung insgesamt erreicht werden. In Milchviehbetrieben zeigen die Ergebnisse, dass die Wasserproduktivität direkt von den Indikatoren für eine höhere Milchproduktivität des Betriebs abhängt, unabhängig von der Art des Produktionssystems, und unterstreichen die Bedeutung der Bewertung dieses Indikators WP auf Betriebsebene. Die dritte Veröffentlichung standen die Umweltauswirkungen der Wassernutzung der Tierhaltung im Fokus. Die Bewertung der Auswirkungen der Wassernutzung ergab eine geringe Wasserknappheit im untersuchten Wassereinzugsgebiet. Die Wasserknappheit ist nicht alarmierend, selbst bei den Szenarien mit geringerer Verfügbarkeit von Wasser. Die Produktion von Schweinen wies den größten „Fußabdruck der Wasserknappheit“ im Wassereinzugsgebiet auf, gefolgt von der Milch- und Geflügelproduktion. Diese Dissertation trägt dazu bei, das Wissen über die Wasserflüsse, die Wasserproduktivität der Schweine- und Geflügelproduktion und die Milchproduktion in verschiedenen Produktionssystemen auf betrieblicher Ebene zu erweitern. Es sind die ersten Berechnungen der Wasserproduktivität dieser Tierproduktionssysteme in brasilianischen Betrieben und die erste Bewertung der Auswirkungen der Wasserknappheit in der Tierproduktion in einem brasilianischen Einzugsgebiet. Zudem wurde das Land Brasilien damit in die internationale wissenschaftliche Diskussion zu diesem Thema eingeführt. Die LEAP-Richtlinien der FAO wurden in dieser ersten Studie in Brasilien erfolgreich angewandt. Auf der Grundlage der Ergebnisse wird eine breite Anwendung der Leitlinien empfohlen, um die Berechnung von zuverlässigen und vergleichbaren Ergebnissen zu gewährleisten und die Entscheidungsfindung von Regierung, Wirtschaft und Gesellschaft im Hinblick auf eine resiliente und nachhaltige landwirtschaftliche Produktionssysteme zu unterstützen. / Water shortages caused by persistent and severe droughts and changes in rainfall patterns are expected to be more frequent and intense due to climate change, increasing water competition and posing food production at risk. Therefore, sustainable and resilient food systems are needed to meet the demand of a growing population. Plant production and animal husbandry account for 72% of the water withdrawn worldwide. Most water consumed in livestock production is for animal feed production. Water is also needed to provide drinking water and to clean and cool the stables. In this context, increasing agriculture and livestock water productivity (WP) is crucial, along with integrated management and governance of water resources. WP describes the ratio of output (e.g. kg milk) to water input (e.g. m³ evapotranspiration). Water input includes direct (e.g. water intake) and indirect (e.g., water for purchased feed) water use. WP calculations are used primarily in evaluating agricultural measures to improve rainfall and technical WP in livestock and crop production. Consistent methods are needed to increase WP and also to reduce the water-related environmental impact of livestock systems. Recently, the Food and Agriculture Organization of the United Nations (FAO), through the Livestock Environmental Assessment and Performance (LEAP) Partnership, launched reference guidelines for assessing water use in livestock production systems and supply chains. The FAO LEAP guidelines aim to understand the water flows on a farm scale and evaluate the contribution of livestock activities to water scarcity, supporting the identification of opportunities to reduce the potential water use impacts in this sector. This cumulative thesis presents the results of the first application of the FAO LEAP guidelines on farms located in Brazil. Three original publications were published in peer-reviewed journals. The WP was calculated based on primary data collected on 115 farms (pig, poultry and dairy) located within the Lajeado Tacongava watershed in southern Brazil, where the water scarcity impact associated with livestock production was assessed. The results of the first two original papers published show the high influence of feed production on the WP of animal products. Therefore, the results emphasize the need for close cooperation between feed production and livestock production to improve WP. Rainfall WP of feed production can be improved to optimize animal nutrition management. In addition, higher livestock WP can be achieved. In dairy farms, results indicate that WP is directly dependent on dairy productivity indicators of the farm, regardless the type of production system, and reinforce the importance of assessing this indicator on a farm scale. In the third publication, the environmental impact of water use in livestock production was investigated. The water scarcity impact assessment demonstrated a low water scarcity in the watershed and it is not alarming even in the driest water flow scenarios. Pig production presented the highest water scarcity footprint in the watershed, followed by dairy farming and poultry production. This dissertation contributes to the advancement of knowledge on the water flows, WP of pig, poultry and milk produced under different production systems on farm scale, which are the first WP benchmarks for these animal production systems in Brazilian farms. It also introduced Brazil to the international scientific discussion on this topic. Some suggestions of potential improvements for the guidelines are presented in this study. The FAO LEAP guidelines were successfully applied in its first study in Brazil. Based on the results of this study, the guidelines’ widespread use is recommended to ensure reliable and comparable results to support government, business and society decision-making toward a more resilient and sustainable food supply chain.

Heat stress (HS) induced changes in energy metabolism, proteolysis, lipogenesis, and oxidative balance have meat quality ramifications for livestock. However, several knowledge gaps exist in understanding heat stressed finishing pig physiology and pork quality characteristics and how dietary zinc may ameliorate undesirable outcomes. Research was completed to determine zinc supplementation effects on carcass composition, meat quality, and oxidative stability of fresh and processed pork from pigs subjected to a chronic, cyclic heat stress using a 2×2×2 factorial arrangement of treatments with main effects of environment (HS vs. thermoneutral; TN), added zinc level (50 vs. 130 mg kg^-1 available zinc), and zinc source (inorganic vs. organic). Commercial crossbred mixed-sex pigs (initially 72.0 kg) were group-housed under either TN (18.9-16.7°C) or cycling HS conditions with chronic diurnal heat (30-29°C/26-27°C for 12h:12h) on days 24-71 with acute heat waves (32-33°C/29-30°C for 12h:12h) on days 21-24, 42-45, and 63-65. One representative pig (<i>n</i>=80) per pen was slaughtered on day 64. The HS pigs were lighter bodyweight (<i>P</i>=0.039), yielded lighter carcasses (<i>P</i>=0.011), less last rib backfat (<i>P</i>=0.032), tended to have smaller loin eye area (<i>P</i>=0.062) but similar percent lean in belly center slices (<i>P</i>>0.10). Compared to TN, HS carcasses had higher 24-h pH (<i>P</i>=0.001) and decreased drip loss (<i>P</i>=0.034). Shifts in individual fatty acid profile of sausage product derived from HS carcasses were observed but were of insufficient magnitude to affect iodine value. Initially, sausage from HS carcasses tended (day 0, <i>P</i>=0.071) to have less thiobarbituric acid reactive substances than TN but over a 10-day simulated retail display, no treatment induced lipid oxidation differences (<i>P</i>>0.05) were observed in either sausage or displayed loin chops. Consistent treatment differences in CIE L*a*b* of products throughout the 10-day display were not observed. The relationships between physiological changes in pigs receiving supplemental zinc and their body and ambient temperatures were also investigated. A representative gilt (<i>n</i>=96) was selected for thermal monitoring from each pen of the 2×2×2 treatments plus 4 additional treatments representing 2 intermediate levels of Zn in both environments. Core body temperatures (T_core) during the day 42-45 acute heat wave were continuously recorded via indwelling vaginal thermometers and infrared thermal imaging was used to measure skin temperatures at 12-hour intervals. From a 64-gilt subset of the 2×2×2 treatments, jejunum and ileum samples were collected on day 64 for analysis of villus height, crypt depth, and jejunal gene expression of heat shock proteins (27, 70, 90), occludin, and mucin (MUC2). The HS model induced thermoregulatory changes and increases in T_core (<i>P</i><0.05). Day 42-45 ambient temperature was negatively correlated with expression of HSP-27 (r=-0.42, <i>P</i>=0.047), HSP-90 (r=-0.49, <i>P</i>=0.014), and occludin (r=-0.69, <i>P</i><0.001) in HS pigs. For the organic Zn supplemented pigs, ambient temperature was positively correlated with expression of HSP-27 (r=0.42, <i>P</i>=0.034) and MUC2 (r=0.45, <i>P</i>=0.017) and negatively correlated with villus height in jejunum (r=-0.42, <i>P</i>=0.027) and ileum (r=-0.38, <i>P</i>=0.048). Thermal Circulation Index (measure of heat dissipation) of HS pigs was negatively correlated with their ileum villus height (r=-0.51, <i>P</i>=0.015) and positively correlated with HSP-70 expression (r=0.46, <i>P</i>=0.041). The T_core lacked correlation with most variables. This research demonstrates cyclic HS affects carcass composition and quality but does not appear to reduce display shelf-life of pork as indicated by lack of differences in lipid oxidation and color stability. In this HS model, zinc level or source imparted negligible benefits and thermal correlations with gut integrity characteristics existed for organic zinc supplemented and HS pigs. The degree of heat dissipation by heat stressed pigs appeared to be associated with classic HS damage and intestinal responses which may be useful indicators of HS in the grow-finish pig. Another agricultural challenge is maintaining higher education programming which establishes a successful career trajectory for agricultural students amid generational shifts in attitudes and background experiences. Undergraduates studying Animal Science and/or Agricultural Economics were surveyed to understand their perception of how collegiate curricular, co-curricular, and extracurricular experiences (coursework, club participation, relevant work experience, international experience, advising/mentoring, college life, and professional networking) contribute to their anticipated career success. A best-worst scaling experiment was used to force respondents (<i>n</i>=487) to make unbiased tradeoffs between the collegiate experience attributes. Responses were then related back to additional demographical and experience/perception characteristics of respondents. Students indicated relevant work experience was overwhelmingly the most critical of the 7 factors (57% preference share), followed by professional networking (19%), and coursework (14%). Students solely in a pre-veterinary Animal Science curriculum represented a distinct category of students regarding their beliefs and experiences. Further research is needed to investigate possible disconnects between student perceptions and reality in higher education and agricultural careers.

There is an extensive debate on the potential environmental impact of dairy farms and in particular the effect of dairy farms on the nitrogen cycle and the effect that this has on ecosystems. Within New Zealand and in particular in the South Island, the expansion of dairying and the adoption of new dairy systems has led to this becoming an increasingly important issue, locally through its effect on water quality and the environment and nationally and internationally through the production of green house gases. Increases in nitrogen usage at the expense of clover nitrogen fixation, irrigation, stocking rate and the introduction of dairy cows onto light free draining soils previously the preserve of arable or sheep farming has led to concern as to the effect intensive pastoral dairying may have on the nitrogen dynamics of the farm and the environment. This study is designed to assess how changes in grazing management in particular changes in pre-grazing and post-grazing residuals alter the clover/ryegrass balance on the farm and the effect that this has on the farm’s nitrogen dynamics. The effects of qualitative changes in grazing management on pasture composition are well established but little is known of the effect of quantitative changes in pasture management on composition, in particular the effect of grazing residuals. There are a number of detailed models of the physiological processes in the energy and nutrient cycling in plants, animals and the soil. There are a smaller number of whole farm models that through integration and simplification of component models attempt to represent the flux of nutrients though a dairy farm. None of these whole farm models is currently able to model the nitrogen flux through a dairy farm at a sufficient level of resolution to capture differences in pasture composition as these occur spatially, temporally and in response to grazing management. This project sought to better understand the nitrogen dynamics on a dairy farm by constructing and then linking component models – a pasture composition and growth model, a cow model, an excretal return model, a soil model and a water balance model – within a whole farm management schedule. The formal null hypothesis is that the mechanistic, mathematical model constructed for this PhD cannot capture and explain the full range of the changes in soil water content, soil nitrogen status, pasture production and composition and animal production, following the alteration in management of the dairy farm between 2002 and 2004. Individual component models were constructed by the author using the computer software package (Matlab) and validated against data extracted from the literature. The models were then converted into one simulation package using C-sharp as the source code language by Elizabeth Post, Senior Computer Scientist at Lincoln Ventures Ltd, Lincoln, New Zealand and the author. This model was then used to investigate the nitrogen dynamics of a dairy farm: the relationship with pasture composition and whether small changes in pasture residuals make a difference to pasture composition and nitrogen dynamics. Two different simulations were run based on the management practice of Lincoln University Dairy farm (LUDF) over two dairy seasons (2002-03 and 2003-04) and validated against the data recorded on this farm. In 2002-03, 50 cows were over wintered and 580 cows were subsequently milked on 200ha. Post grazing residuals where maintained at 1600-1750KgDM/ha. In 2003-04, 125 cows were overwintered and 635 cows were milked on 200ha with post grazing residuals maintained at 1400KgDm/ha. All models operate on a daily time step. Within the pasture model composition is described by 9 state variables describing different components of the pasture and pasture growth is modelled mechanistically from a calculation of component photosynthesis. A further 9 state variables describe the nitrogen composition of the pasture components. The soil model is a variable two layer, mechanistic representation, parametised for the shallow, stony soils of LUDF. Soil water status is an input for the pasture model while water uptake by the growing plants affects the soil water balance within the soil model. Animal intake and production are modelled mechanistically with model cows described in terms of their age, genetic merit, body weight, breed, pregnancy status, conception date and body condition score. Each cow type produces a different quantity of urinary and faecal excretion which varies with dry matter intake, milk yield and the sodium and potassium status of the pasture. Excretal nitrogen composition is predicted within a separate model which calculates daily nitrogen excretion in faeces, urine and milk. Excretions are deposited randomly over the grazed area and account is taken of overlapping excretions that are created on the same day and overlaps that occur with older excretal patches deposited in previous grazing rounds. Each excretal patch has its own associated pasture, water and soil model reflecting the differences in nitrogen status between patches. Grazing preference is expressed within the model between different classes of excretal patch and between excretal patches and the base pasture and between clover and grass. Supplementary silage is conserved and fed according to the management schedule of LUDF. Cows calve, become pregnant and are dried off within the model according to the relevant records from LUDF. Cows are deemed to arrive on the farm on the day of calving and to leave on the day that drying off is finished (a 5 day procedure within the model), except for those cows that are overwintering which remain on the farm. The soil model has multiple nitrogen/carbon pools and is dynamically linked to all the other models. External nitrogen losses from the system are modelled as volatilisation, leaching and denitrification, with pasture nitrogen uptake from the soil model and fixation by clover from the atmosphere. Both the individual component models and the final assembled composite model were successful in matching the available data in terms of pasture and animal production, pasture composition, soil water balance and nitrogen status and external losses. The model indicates that the low residual, high stocking rate farm returns more excreta to the soil. However, this is countered by a reduction in the amount of dead material returned to the paddock and this reduces the relative size of the pool of nitrogen in the dead organic matter. This produces a relative lack of substrate for the soil microbes which are thus unable to exploit all of the nitrogen in the available pool. Soil ammonium and nitrate pools are also increased from the increase in faecal and urinary return so precipitating an immobilising flux from these larger pools to the smaller pool of nitrogen available to the soil microbes. However, the relative inability of the soil bacteria to fully exploit this means that the production of soil organic live matter and the resulting mineralising flux from the dead organic matter pool through the available pool to the ammonium and nitrate pools is reduced. The larger ammonium and nitrate pools will also be associated with increased external losses from the system as denitrification, leaching and volatilisation are increased. The increase in the clover percentage within the sward in 2003-04 led to greater nitrogen fixation and the model suggests that some of the extra nitrogen is effectively captured by the animals in increased production. However, the reduction in the return of dead matter coupled with an increase in excretal return and the consequent increase in the mineral nitrogen pools within the soil lead to greater losses of nitrogen from the soil.

By far the greatest proportion of the 1,150,000 acres of light land in Canterbury is found on the Canterbury Plain. This plain, originally covered by "low tussock" and of easy contour, was enticing to the early pioneers and became one of the earliest areas in New Zealand to be settled and farmed. Over the years it has developed into one of the most intensively farmed and productive areas of New Zealand. The dominant characteristic of the light land of Canterbury is undoubtedly the climate. The rainfall is reasonably evenly distributed over the year, but because of the low humidity, high temperatures and warm winds experienced over the summer in association with a free draining soil, the effectiveness of the rainfall over this period is drastically reduced. Consequently active plant growth is severely restricted for several months over the summer, and occasionally extends into the spring and/or autumn periods. The uncertainty as to the length and severity of this restricted growth period and the associated problem of equating the variable feed supply to the stock requirements, both within and between years, is the basic problem confronting the light land farmer. In spite of the environmental difficulties the productivity of the light land has increased several fold since early settlement. The original holdings on the Canterbury Plain were large with their boundaries on the rivers so as to provide access to water. Fine wool sheep were extensively grazed. However the introduction of refrigerated shipping and the extension of the water race system in the 1880's brought about a reduction in the size of holdings and a change in the pattern of farming. Dual purpose sheep were run and by the 1930's in response to favourable crop prices the system of diversified farming was firmly established. Unfortunately this system placed excessive emphasis on cash cropping, particularly on the light soils. Soil fertility was drained, structure severely damaged and subsequent pasture establishment and survival poor. In the late 1940s and early 1950s, with declining crop yields and with more favourable prices being obtained for fat lambs and particularly wool, the emphasis shifted from cropping to livestock farming. The carrying capacity however, was restricted by the reduced soil fertility and poor quality pastures and an environment in which climatic uncertainty tended to inhibit the rapid expansion of stock numbers. The results of research work carried out at the various institutions in Canterbury over the years have undoubtedly promoted a greater understanding and appreciation of the problems confronting the farmer and the limitations of the particular environment in which he must operate. For example, pasture species more suited to the low fertility conditions and climate were introduced with spectacular results. The most significant of these was subterranean clover (introduced in the 1930s), noted for its ability to withstand the summer droughts, to regenerate in the autumn, and to provide an increased bulk of feed in the spring. Research work had shown that both lime and phosphate were necessary on the light land soils, if high pasture production and persistency was to be expected. Soil fertility increased subsequent to a reduction in the emphasis on cropping and with the higher levels of fertiliser application. High fertility pasture species (e.g. white clover and lucerne), were introduced and not only gave higher and more reliable total production but exhibited improved seasonal spread of production. Investigations into pasture diseases and stock health provided answers to specific problems. Research into flock management generally and in comparisons between the productivity of various sheep breeds indicated the most suitable type of flock and breed for the light land farmer. From this and other research work (in conjunction with the observations of leading farmers in the area), an efficient system of light land farming has gradually evolved in which many of the basic problems have been overcome and which has resulted in a raising of the carrying capacity of the light land from ¾ stock unit per acre in the 1930's to 3½-4 stock units per acre at present. A central feature of this system (particularly at high stocking rates), is the high degree of flexibility incorporated in both the stock policies and feed supplies. Where the objective function is to maximise productivity over a period of years, it is essential to utilise the available spring feed efficiently while maintaining the ability to destock when confronted with feed shortages in the spring and early summer. Because of the fluctuating feed supply, which is characteristic of light land, the need to maintain feed reserves and to incorporate a high degree of flexibility in the stock policy is evident if the feed supply and demand are to be equated. In summary, the increased productivity can be attributed to two factors: (1) The ability to grow a greatly increased quantity of herbage per acre with an improved seasonal pattern of production. (2) A more efficient utilisation of the herbage produced. Unlike his counterpart in more reliable farming districts, the light land farmer operates in an environment of uncertainty. Yield uncertainty, particularly at high stocking rates, is the major problem to be overcome and this dictates very largely the system of farming adopted. Price uncertainty is also a significant aspect of light land farming because of the reliance on a limited range of products and the inability to diversify. In an analysis of physical and financial data collected from a sample of light land farms in Canterbury (1) there was no evidence to suggest that any one particular pattern of output was superior to all others. This result was surprising, but may reflect the uncertainty inherent in the environment. (1) For a full discussion on this, see Section 3.3.2(a). Alternatively it may infer that the actual patterns of production are less important than the managerial skill with which they are implemented. These results pointed to the need to explore more fully the following facets of light land management: (1) Given a developed farm, is there any one optimal pattern of production which (a) generates increased profit under average seasonal and price conditions, and (b) is subject to only small variations in profit under changing seasonal and price conditions? (2) Given the potential for the development and expansion of light land farming, how profitable is this from the individual farmer's viewpoint? If, in an evaluation of the first problem, high levels of productivity are shown to be profitable on existing well developed farms, then a reallocation of resources to obtain the desired combination should be recommended. An optimum combination of enterprises shown by such an analysis might well serve as the goal where an undeveloped potential still exists on a farm and where a reallocation and intensification in the use of resources is necessary if productivity is to be increased. In this study of light land farming two case farms have been used and although the results refer specifically to these particular farms, some conclusions of a general nature are possible. In Chapter II the physical characteristics of the area are described. In Chapter III a review of the research into specific problems relating to the management of light land is presented. This is followed in Chapter IV by an explanation of the technical principles of light land farming which have evolved. Chapter V is devoted to the comparison of some of the production possibilities open to the light land farmer using linear programming. An analysis of light land development 1s presented in Chapter VI, while Chapter VII presents the conclusions and summary of the study.

By far the greatest proportion of the 1,150,000 acres of light land in Canterbury is found on the Canterbury Plain. This plain, originally covered by "low tussock" and of easy contour, was enticing to the early pioneers and became one of the earliest areas in New Zealand to be settled and farmed. Over the years it has developed into one of the most intensively farmed and productive areas of New Zealand. The dominant characteristic of the light land of Canterbury is undoubtedly the climate. The rainfall is reasonably evenly distributed over the year, but because of the low humidity, high temperatures and warm winds experienced over the summer in association with a free draining soil, the effectiveness of the rainfall over this period is drastically reduced. Consequently active plant growth is severely restricted for several months over the summer, and occasionally extends into the spring and/or autumn periods. The uncertainty as to the length and severity of this restricted growth period and the associated problem of equating the variable feed supply to the stock requirements, both within and between years, is the basic problem confronting the light land farmer. In spite of the environmental difficulties the productivity of the light land has increased several fold since early settlement. The original holdings on the Canterbury Plain were large with their boundaries on the rivers so as to provide access to water. Fine wool sheep were extensively grazed. However the introduction of refrigerated shipping and the extension of the water race system in the 1880's brought about a reduction in the size of holdings and a change in the pattern of farming. Dual purpose sheep were run and by the 1930's in response to favourable crop prices the system of diversified farming was firmly established. Unfortunately this system placed excessive emphasis on cash cropping, particularly on the light soils. Soil fertility was drained, structure severely damaged and subsequent pasture establishment and survival poor. In the late 1940s and early 1950s, with declining crop yields and with more favourable prices being obtained for fat lambs and particularly wool, the emphasis shifted from cropping to livestock farming. The carrying capacity however, was restricted by the reduced soil fertility and poor quality pastures and an environment in which climatic uncertainty tended to inhibit the rapid expansion of stock numbers. The results of research work carried out at the various institutions in Canterbury over the years have undoubtedly promoted a greater understanding and appreciation of the problems confronting the farmer and the limitations of the particular environment in which he must operate. For example, pasture species more suited to the low fertility conditions and climate were introduced with spectacular results. The most significant of these was subterranean clover (introduced in the 1930s), noted for its ability to withstand the summer droughts, to regenerate in the autumn, and to provide an increased bulk of feed in the spring. Research work had shown that both lime and phosphate were necessary on the light land soils, if high pasture production and persistency was to be expected. Soil fertility increased subsequent to a reduction in the emphasis on cropping and with the higher levels of fertiliser application. High fertility pasture species (e.g. white clover and lucerne), were introduced and not only gave higher and more reliable total production but exhibited improved seasonal spread of production. Investigations into pasture diseases and stock health provided answers to specific problems. Research into flock management generally and in comparisons between the productivity of various sheep breeds indicated the most suitable type of flock and breed for the light land farmer. From this and other research work (in conjunction with the observations of leading farmers in the area), an efficient system of light land farming has gradually evolved in which many of the basic problems have been overcome and which has resulted in a raising of the carrying capacity of the light land from ¾ stock unit per acre in the 1930's to 3½-4 stock units per acre at present. A central feature of this system (particularly at high stocking rates), is the high degree of flexibility incorporated in both the stock policies and feed supplies. Where the objective function is to maximise productivity over a period of years, it is essential to utilise the available spring feed efficiently while maintaining the ability to destock when confronted with feed shortages in the spring and early summer. Because of the fluctuating feed supply, which is characteristic of light land, the need to maintain feed reserves and to incorporate a high degree of flexibility in the stock policy is evident if the feed supply and demand are to be equated. In summary, the increased productivity can be attributed to two factors: (1) The ability to grow a greatly increased quantity of herbage per acre with an improved seasonal pattern of production. (2) A more efficient utilisation of the herbage produced. Unlike his counterpart in more reliable farming districts, the light land farmer operates in an environment of uncertainty. Yield uncertainty, particularly at high stocking rates, is the major problem to be overcome and this dictates very largely the system of farming adopted. Price uncertainty is also a significant aspect of light land farming because of the reliance on a limited range of products and the inability to diversify. In an analysis of physical and financial data collected from a sample of light land farms in Canterbury (1) there was no evidence to suggest that any one particular pattern of output was superior to all others. This result was surprising, but may reflect the uncertainty inherent in the environment. (1) For a full discussion on this, see Section 3.3.2(a). Alternatively it may infer that the actual patterns of production are less important than the managerial skill with which they are implemented. These results pointed to the need to explore more fully the following facets of light land management: (1) Given a developed farm, is there any one optimal pattern of production which (a) generates increased profit under average seasonal and price conditions, and (b) is subject to only small variations in profit under changing seasonal and price conditions? (2) Given the potential for the development and expansion of light land farming, how profitable is this from the individual farmer's viewpoint? If, in an evaluation of the first problem, high levels of productivity are shown to be profitable on existing well developed farms, then a reallocation of resources to obtain the desired combination should be recommended. An optimum combination of enterprises shown by such an analysis might well serve as the goal where an undeveloped potential still exists on a farm and where a reallocation and intensification in the use of resources is necessary if productivity is to be increased. In this study of light land farming two case farms have been used and although the results refer specifically to these particular farms, some conclusions of a general nature are possible. In Chapter II the physical characteristics of the area are described. In Chapter III a review of the research into specific problems relating to the management of light land is presented. This is followed in Chapter IV by an explanation of the technical principles of light land farming which have evolved. Chapter V is devoted to the comparison of some of the production possibilities open to the light land farmer using linear programming. An analysis of light land development 1s presented in Chapter VI, while Chapter VII presents the conclusions and summary of the study.

New Zealand mutton bird or tītī (Puffinus griseus and order procellariiformes) nest in New Zealand during the summer months, migrate to the northern hemisphere during May and return in September. Their eggs are laid during November and December and the chicks are hatched in the following January and February. Large numbers of them are harvested from April to May in New Zealand. They are wild seabirds annually harvested by Maori according to the customary rights agreement set by Treaty of Waitangi.NZ mutton birds also called Sooty Shearwaters are noted for their high proportion of body fat.These birds are interesting since its sole diet is based on krill and other small marine organisms that are potentially rich in n-3 fatty acids and other marine bioactive compounds. The proximate composition, fatty and amino acids and cholesterol content of mutton bird pectoral muscle were determined and compared with other common meat to explore the nutritional value of this New Zealand delicacy. The concentration of twenty two essential and toxic elements including silver (Ag), aluminium (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), lead (Pb), selenium (Se), potassium (K), calcium (Ca), magnesium (Mg), boron (B), iron (Fe), nickel (Ni), sulphur (S), sodium (Na) and cobalt (Co) and zinc (Zn) in mutton bird breast meat (Puffinus griseus) were measured over two years to evaluate its safety for human consumption. Persistent organochlorine, dichlorodiphenyltrichloroethane (DDT) and their metabolites, and aldrin and lindane were also measured.Twenty bird carcasses were purchased in both 2006 and 2007 from a local source. Meat samples from the pectoral muscle of two carcasses were pooled to generate 10 samples for each year. These were used for trace element analysis using inductively coupled plasma-mass spectrometry (ICP-MS). Trace elements were in the range of 0 to 1.09 mg/kg wet weight for Ag, 0 to 3.32 for Al, 0.17 to 0.79 for As, 0.01 to 0.07 for Cd, 0.03 to 0.15 for Cr, 3.56 to 4.88 for Cu, 0 to 0.15 for Hg, 0.22 to 0.50 for Mn, 0 to 0.09 for Pb, 0.66 to 1.18 for Se and 11.49 to 23.70 for Zn. In 2006, Ag, Al, Mn and Zn concentrations were significantly higher but Pb and Hg concentrations significantly lower compared to the 2007 samples (P < 0.05). Apart from one sample in 2006, all the samples were below the published maximum level for concern. However, our preliminary data indicated that the higher level of Cd and other metals in the skin of mutton bird may compromise the overall safety to humans consuming the skin of mutton birds. It is suggested that the evaluation of the metals in different parts and/or the whole mutton bird at different seasons is required to assure complete safety to the consumers.Furthermore, the nutritional value of mutton bird meat was studied over two harvesting seasons (2006 and 2007) to investigate the impact of seasonal variation. The moisture and carbohydrates contents ranged between 54.0 to 55.0 % and 2.8 to 3.0 %, respectively, and no seasonal effects were evident in these components. The values for fat and ash contents were higher and the protein content lower for birds harvested in 2007 compared with the 2006 values which ranged from 11.8 to 13.0, 10.3 to 11.7, and 20.3 to 18.5 % for fat, ash and protein content respectively. The major amino acids in mutton bird pectoral muscle were glutamate, aspartate, lysine, leucine, and arginine. Higher lysine concentrations and lower proline, cystein and methionine were found in mutton birds compared with the literature values for beef, lamb and pork. The essential amino acid content in mutton bird (43.8 and 44.9 % in 2006 and 2007, respectively) was slightly higher than those found in beef and lamb meats (42-43%).The major fatty acids detected were palmitic (C16:0), stearic (C18:0), oleic and isomers (C18:1), eicosenoic (C20:1), Docosahexaenoic acid (DHA) (C22:6), icosapentaenoic acid (EPA) (C 20:5) and these accounted for approximately 77% of the fatty acids. The 3/6 ratio of fats from pectoral muscle was 1.3. The cholesterol concentration varied slightly in the two years with 184.4±37.37and 134.4±25.55mg/100 g fresh weight for 2007 and 2008 respectively. Mutton bird was shown to contain significantly higher cholesterol content (134.4-184.4) than other common meat such as chicken (80.3-88.9), lamb (62.3), fish (52.79) and beef (51.97). Overall, the nutritional value of mutton bird muscle was similar to or superior to the traditionally protein sources such as seafood and red meat. Annual variations existed in the composition of Mutton bird pectoral muscle but this is not of nutritional consequence but might be a useful indicator for ecological events such as feed availability and other environmental issues. Mutton bird seems to be a good source of essential minerals, Zn and Fe compared with other traditional meats source. Mutton bird meat is nutritionally as good as the major sources of red or white meats. It may even have advantages over the other common meats (beef, lamb, fish and chicken) due to its high protein and monounsaturated fatty acids (omega n-3 and n-6) content. However, its high cholesterol content may represent a risk factor for some people.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-24T20:10:35Z No. of bitstreams: 1 NEILA LIDIANY RIBEIRO - DISSERTAÇÃO PPGEA 2006..pdf: 12712674 bytes, checksum: 256a12bd01632a9502b9eb4794b1886d (MD5) / Made available in DSpace on 2018-05-24T20:10:35Z (GMT). No. of bitstreams: 1 NEILA LIDIANY RIBEIRO - DISSERTAÇÃO PPGEA 2006..pdf: 12712674 bytes, checksum: 256a12bd01632a9502b9eb4794b1886d (MD5) Previous issue date: 2006-02 / Capes / O presente trabalho teve como objetivo determinar os índices de conforto térmico em instalações para ovinos e analisar os parâmetros fisiológicos e o grau de adaptabilidade de quatro grupos genéticos de ovinos, em São João do Cariri, PB. Foram utilizados 40 animais, 10 por grupo genético, que foram o Cariri, Morada Nova, Barriga Negra e Cara Curta, todos fêmeas, alojadas em 4 apriscos. Os dados ambientais analisados foram a temperatura do ar (TA), umidade relativa do ar (UR), velocidade do vento (Vv), temperatura de globo negro (Tgn), índice de temperatura do globo negro e umidade (ITGU), carga térmica de radiação (CTR). Os dados fisiológicos analisados foram: a frequência respiratória (FR), frequência cardíaca (FC), temperatura retal (TR) e temperatura superficial (TS), medidos nos horários das 9 e 15 h. O grau de adaptabilidade foi realizado através do teste de Baccari Júnior. A avaliação dos dados foi realizada por um delineamento inteiramente casualizado em um fatorial 4x2, sendo 4 grupos genéticos e dois turnos. Os índices ambientais, no período da tarde, foram superiores aos da manhã e tiveram seus valores, com exceção da UR e Vv, acima da faixa considerada normal. A TR, FR, FC e TS no turno da tarde estiveram mais elevados do que no turno da manhã, sendo que a TR esteve dentro da faixa normal e a FR e FC acima da recomendada. O índice de tolerância ao calor não apresentou diferença significativa entre os grupos genéticos e mostrou que os animais, mesmo elevando a FR e FC, apresentaram alta capacidade de adaptação a região. / The present work had the aim to determine thermal means at installation to ovines and analyse physiological parameters and way of life degree of 4 genetic groups, in the dry region of Paraíba. It had been used 40 animais, 10 per genetic group: Cariri, Morada Nova, Barriga Negra and Cara Curta ,all of them were female ,kept in 4 places by chance .Data were air temperature (TA), air relative humidity (UR), wind speed (Vv), dark block temperature (Tgn), humidity and dark block temperature (ITGU), radiation thermal support (CTR). Physiological data were respiratory frequency ( FR), heart frequency (FC), bottom temperature (TR) and superficial temperature (TS), evaluated for 9 and 15 h. Way of life degree was carried out by Baccari Júnior Test. Data evaluation was carried out in randomized sketching in 4x2, being 4 genetic groups and two periods Environmental means ,in the afternoon, were upper to the moming ones and had its values, with exception to UR and Vv, increased to the normal tax. TR, FR, FC and TS in the afternoon were higher than in the morning, but TR normally and FR and FC upper to the normal. ITC did not show significance difference among genetic groups and showed that the animais, with higher FR and FC showed high capacity to the region.

[EN] The state of the Spanish aquaculture Sea bream, Sea bass and Meagre produced in fish farms in the Spanish Mediterranean coast is analyzed setting as objective the analysis of the economical and financial situation of companies in the sector to characterize the successful companies. For this project a study was made during the period from 2002 to 2011, on the period before the economical crisis (2002-2007) and also during the crisis (2007-2011), to interpret the evolution of the companies from the financial and economical information extracted from their financial statements filed with the Companies Registry and are supplied by the SABI database. Economic and financial ratios of the sample aquaculture companies located in the Mediterranean coast examines representing 63% (2007), production of Sea bream, Sea bass and Meagre in Spain using statistical correlation analysis, principal components and cluster group that have allowed companies based on their financial situation. The combination of the economic and financial ratios to define a "Success Rate" of companies, it helps to know the status of each within the sector in relation to other companies, from assessing economical and financial variables if the steps taken leading to success or failure and thus becoming a key tool in making decisions at the enterprise level. The results indicate that only companies with high volume production or small well-managed companies have been able to withstand periods of economical crisis. Likewise, annual ratios of companies with best results in each period are analyzed to define the business model of success that is configured as necessary reference in the process of management in the aquaculture sector. During this time the evolution of the sales prices of the different aquatic species in Spain is also studied, from data the wholesale markets, the price observatory of the Ministerio de Agricultura, Alimentación y Medio Ambiente, and Mis Peces portal, as the price is vital for good economical performance, along with a sound technical and economical-financial management. The concept of "success rate" is new in this sector, it has developed a valid tool for studying the situation of companies within the aquaculture sector from the financial economic variables, easily accessible to the Financial Statements proceed with a reasonable degree of reliability compared to other more subjective variables. / [ES] Se analiza el estado de la acuicultura española de la dorada, lubina y corvina producidas en granjas marinas en el litoral del mar Mediterráneo español, fijándose como objetivo el análisis de la situación económico-financiera de las empresas del sector para caracterizar a las empresas de éxito. Para ello se realiza un estudio durante el periodo desde el año 2002 hasta el 2011, espacio de tiempo previo a la crisis económica (2002-2007) y durante la crisis (2007-2011), para analizar la evolución de las empresas a partir de la información económica financiera extraída de sus estados contables depositados en el Registro Mercantil y que son suministrados por la Base de Datos SABI. Se examinan los ratios económico-financieros de la muestra tomada de empresas de acuicultura ubicadas en el litoral Mediterráneo que representan el 63 % (2007), de la producción de dorada, lubina y corvina en España mediante análisis estadísticos de correlación, componentes principales y clúster, que han permitido agrupar a las empresas en función de su situación económico-financiera. La combinación de los ratios económico-financieros permite definir un "Índice de Éxito" de las empresas, que ayuda a conocer la situación de cada una de ellas dentro del sector en relación al resto de empresas, evaluando a partir de variables económico financieras si la gestión realizada lleva al éxito o al fracaso y convirtiéndose así en una herramienta clave en la toma de decisiones a nivel empresarial. Los resultados indican que solo empresas con gran volumen de producción o pequeñas empresas bien gestionadas, han sido capaces de soportar el periodo de crisis económica. Asimismo, se analizan los ratios anuales de las empresas con mejores resultados en cada periodo para definir el modelo de empresa de éxito que se configura como referencia necesaria en el proceso de gestión en el sector de la acuicultura. Durante este tiempo también se estudia la evolución de los precios de venta de las diferentes especies acuícolas en España, a partir de los datos de la Red de Mercas, el Observatorio de Precios del Ministerio de Agricultura, Alimentación y Medio Ambiente, y el portal Mis Peces, pues el precio de venta es vital para obtener buenos resultados económicos, además de una buena gestión técnica y económico-financiera. El concepto del "Índice de Éxito" resulta novedoso en este sector, pues se ha desarrollado una herramienta válida para estudiar la situación de las empresas dentro del sector acuícola a partir de las variables económicas financieras, fácilmente accesibles al proceder de los Estados Contables y con un razonable grado de fiabilidad frente a otras variables más subjetivas. / [CA] S'analitza l'estat de l'aqüicultura espanyola de l'orada, llobarro i corbina produïdes en granges marines al litoral del mar Mediterrani espanyol, establint com a objectiu l'anàlisi de la situació económica i financera de les empreses del sector per tal de caracteritzar les empreses d'èxit. Per a això, es realitza un estudi durant el període des de l'any 2002 fins al 2011, que inclou un espai de temps previ a la crisi econòmica (2002-2007) i altre durant la crisi (2007-2011), per analitzar l'evolució de les empreses a partir de la informació econòmica-financera extreta dels seus estats comptables dipositats en el Registre Mercantil, i que són subministrats per la base de dades SABI. S'examinen les ràtios econòmicofinanceres d'un conjunt d'empreses d'aqüicultura ubicades al litoral Mediterrani, que representen el 63% (2007), de la producció d'orada, llobarro i corbina a Espanya, mitjançant diferents anàlisis estadístics, com l'anàlisi de correlació, components principals i clúster, que han permès agrupar les empreses en funció de la seva situació economicofinancera. La combinació de les ràtios economicofinanceres permet definir un "Índex d'Èxit" de les empreses, que ajuda a conèixer la situació de cadascuna d'elles dins del sector en relació a la resta d'empreses, avaluant a partir de variables econòmico-financeres si la gestió realitzada duu a l'èxit o al fracàs, convertint-se així en una eina clau en la presa de decisions a nivell empresarial. Els resultats indiquen que només empreses amb gran volum de producción, o xicotetes empreses ben gestionades, han estat capaços de suportar el període de crisi econòmica. Així mateix, s'analitzen les ràtios anuals de les empreses amb millors resultats en cada període per definir el model d'empresa d'èxit, esdevenenint aquest una referència necessària en el procés de gestió en el sector de l'aqüicultura. També s'estudia l'evolució dels preus de venda de les diferents espècies aqüícoles a Espanya durant el període entre 2002 i 2011, a partir de les dades de la Red de Mercas, l'Observatori de Preus del Ministeri d'Agricultura, Alimentació i Medi Ambient i el portal Mis Peces, ja que el preu de venda és vital per obtenir bons resultats econòmics, a més de la realització d'una bona gestió tècnica i econòmicofinancera. El concepte d'"Índex d'Èxit" és nou en aquest sector, i representa una eina vàlida per estudiar la situació de les empreses dins del sector aqüícola a partir de les variables econòmico-financeres, fàcilment accessibles ja que procedeixen dels estats comptables, i amb un raonable grau de fiabilitat en comparació amb altres variables més subjectives. / Benito Alas, F. (2016). ANÁLISIS DE LA SITUACIÓN ECONÓMICA-FINANCIERA DEL SECTOR PRODUCTOR DE LA DORADA (Sparus aurata L.), LUBINA (Dicentrarchus labrax L.) Y CORVINA (Argyrosomus regius A.), EN EL LITORAL MEDITERRANEO ESPAÑOL [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62187