Este é um estudo comparativo do comportamento e da comunicação acústica de cobaias – Cavia porcellus - e de preás – C. aperea - duas espécies muito próximas, uma com uma história recente de domesticação (há 6.000 anos nos Andes) e a outra selvagem. Inclui três etapas: (1) a elaboração de um etograma e a comparação entre cobaias e preás quanto à freqüência e duração dos comportamentos exibidos em contextos sociais particulares (encontros entre fêmeas, entre machos e entre macho e fêmea); (2) a categorização e análise sonográfica comparativa da estrutura dos sinais sonoros; e (3) a comparação entre espécies quanto ao uso dos chamados através de um estudo do comportamento do emissor e de um receptor, no momento anterior e subseqüente à emissão. Encontramos diferenças entre as espécies nas três etapas. (1) Cobaias exibiram mais comportamentos de contatos e sexuais; preás exibiram mais comportamentos de exploração. (2) Das emissões registradas, uma não foi exibida por cobaias. Analisamos 4 delas estatisticamente e todas revelaram diferenças estruturais entre espécies. (3) Houve diferença no uso do sinal de alerta e no nível de resposta eliciado por alguns sinais. Os resultados são discutidos principalmente como efeitos da domesticação. A seleção de animais maiores pode ter alterado a morfologia do trato vocal das cobaias, produzindo as mudanças na estrutura dos chamados. Ainda, com o relaxamento de seleção natural, por conta da proteção oferecida pelo cativeiro, características menos favoráveis podem ter sido mantidas e ganhado proporção na população. Como resultado, a espécie domesticada produz e reage menos aos sinais de alerta, gasta menos tempo com comportamentos de atenção ao meio e ganha tempo para os comportamentos socais e reprodutivos. / This is a comparative study of behavior and acoustic communication of wild (Cavia aperea) and domestic (C. porcellus) cavies. Animals were observed in the laboratory in three social situations (female-female, male-male and female-male pairings) and the following steps were performed: (1) comparison of the frequency and duration of behaviors, in both species; (2) description and comparison of the sonografic parameters of acoustic signals emitted by individuals of both species; and (3) identification of antecedent and subsequent behavioral contexts of such signals as an approach to the understanding of their social function. C. porcellus exhibited more contact and sexual categories of behaviors than C. aperea; C. aperea explored more than C. porcellus. Signal repertoire was almost the same (one, out of 7 calls was exclusively emitted by C. aperea). Statistical analysis revealed significant structural differences between species in four of the calls. Differences were also found in the context of use of alert vocalization and in the level of response elicited by some signals. Interspecific differences found may be partially attributed to domestication. Selection for meet production may have altered guinea pigs’ vocal tract and may have brought changes in acoustic signals structure. The absence of predatory pressure and the less demanding conditions of captivity may have favored the expression of some traits, such as the performance of long courtship bouts. The domestic cavies C. porcellus are less prone than the wild ones to emit and to respond to alert signals, spend less time with exploratory and patrolling and spend more time with social and reproductive interactions.

Thesis (Ph.D. (Animal Production)) --University of Limpopo, 2018 / Pigs are of high economic importance, especially among the smallholder pig farmers as they contribute to human nutrition, food security, poverty alleviation, enhanced livelihood and creation of employment for the rural community. However, reproductive inefficiency is the main limiting factor due to inaccessibility to superior germplasm. Therefore, advances in reproductive technologies such as oestrus synchronization and artificial insemination (AI) offers unprecedented opportunities for livestock improvement for smallholder pig farmers. The first objective determined the status of pig productivity in smallholder farms of Gauteng Province prior to the introduction of advanced reproductive technologies (ARTs). The population was divided into four strata, namely West Rand, Ekurhuleni, Tshwane and Sedibeng district municipalities. A proportional stratified random sampling procedure was used to select 71 smallholder pig farmers with the assistance of extension officers from Gauteng Department of Agriculture and Rural Development (GDARD). The majority of the respondents were males (67%) and were above 50 years of age (67%), whilst 56% of the respondents had high school education. Majority of the respondents privately owned the farms (62%) and the farm infrastructure had facilities with low cost housing and modern facilities. Additionally, 47% of the respondents fed their pigs with feed swill. A large proportion of the respondents did not vaccinate their pigs (81%). Majority of respondents did not identify their pig herds (63%). Interestingly, majority of the respondents did not have breeding boars (73%) and sold their pigs at auctions (70%). The second objective determined semen characteristics evaluated by a Computer Aided Sperm Analyser® (CASA®) as a measure of boar fertility to be used for artificial insemination (AI). Sixteen ejaculates were collected from three Large White boars that are routinely used for semen collection purposes using the gloved-hand technique. The semen was extended with a commercial semen extender; Beltsville Thawing Solution, and the AI dose used consisted of 80mL semen sample (3×109 spermatozoa/mL). Aliquots of diluted semen were evaluated for spermatozoa motility using CASA®. Spermatozoa viability was evaluated using Synthetic Binding CD-14 (SYBR+)/Propidium Iodide (PI-), whereas spermatozoa morphology was evaluated using Eosin Nigrosin stain. The average semen volume, concentration and pH were 210 mL, 264.8 x 106 spermatozoa/mL and 7.1, respectively. The average values for total spermatozoa motility was 95.1%, ranging from 82.7 and 98.5%. However, XIX there were lower values found for progressive spermatozoa motility, ranging from 13.6 to 39.0%. The mean values for morphologically normal spermatozoa ranged from 47.8-60.9% and live spermatozoa ranged from 71.8-77.7%. The third objective determined sow fertility following AI at smallholder farms A total of 73 multiparous sows were artificially inseminated. Conception rates, farrowing rates, litter size and number born alive were recorded. The average conception and farrowing rates were 78.1 and 57.5%, respectively. Furthermore, AI resulted in acceptable fecundity (i.e., 11.8 litter size and 10.0 number of piglets born alive). The fourth objective determined the relationship between spermatozoa quality characteristics and sow fertility at smallholder farms in Gauteng Province. Of all fertility characteristics studied, conception rate was significantly related to total spermatozoa motility rate (r= 0.37, P<0.01), progressive motility (r= 0.31, P<0.01) and rapid motility (r= 0.40, P<0.01), although relatively low. There was a low negative relationship between spermatozoa morphological characteristics and fertility (P>0.05). The fifth objective determined the pre-weaning growth performance of piglets born following AI at smallholder farms of Gauteng province. Individual piglets were weighed using an electronic weighing scale. Litter size, number of piglets born alive, number of piglets weaned, the average piglet birth weight and average piglet weaned weight were recorded. The average litter size was 11.8 ± 0.2. The average birth weight and weaning weights were 1.9 and 6.2 kg, respectively. No significant differences were found between male and female piglets for all the growth performance characteristics. Piglets born during winter had a significantly higher (P<0.05) birth and weaning weight as compared to autumn and summer months. Season had a significant effect on birth and weaning weight (P<0.01). However, sex of piglets had no effect on all the characteristics recorded (P>0.05). The interaction between sex and season was only observed on the total number of weaned piglets (P<0.01). A highly significant positive correlation was found between litter size and number of piglets born alive (r= 0.86) and total number of piglets weaned (r= 0.50). A highly significant correlation was found between total number of piglets born alive and total number of piglets weaned (r= 0.55). In conclusion, the study demonstrated the potential benefit of adopting AI technology under smallholder production systems to disseminate superior genetic material to smallholder pig farmers in Gauteng Province. The total spermatozoa motility, progressive and rapid spermatozoa motility were the only spermatozoa motility characteristics significantly correlated XX with conception rate. Conversely, litter size and number born alive were not correlated with CASA® spermatozoa motility attributes. No relationships existed between spermatozoa morphological characteristics and fertility. The sex ratio percentage of piglets born following AI was 52:48% (females: males). The number of piglets born alive was 10.2 and 9.5 for number piglets weaned. Season influenced birth to weaning weight. However, sex had no significant influence at birth and weaning weight. Litter size affects the number of piglets born alive and weaned. The study showed that the introduction of advanced reproductive technologies improved productivity of pigs at smallholder pig farms in Gauteng Province. / Gauteng Department of Agriculture and Rural Development (GDARD) and Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL

La tesi es compon de tres estudis que es van realitzar amb la finalitat de disminuir el cost analític que suposa la determinació rutinària de la greix intramuscular (GIM) i de l'àcid oleic, així com d’investigar els mecanismes biològics de la deposició del greix. En el primer estudi, es va desenvolupar un mètode analític d'alt rendiment per a la quantificació de l'àcid oleic en carn de porc, mitjançant un sistema d'anàlisi per injecció de flux basat en una espectrometria de masses amb ionització per electrosprai. El nou mètode, que permet una quantificació ràpida del contingut en àcid oleic en mostres petites, podria ser adequat per a la classificació de porcs i canals pel seu contingut en àcid oleic. El segon estudi, avalua l'ús d'indicadors lipídics en sèrum com biomarcadors precoços de la composició i contingut del GIM i del greix subcutani. Cap dels indicadors lipídics investigats es recomanen com un biomarcador precoç del greix. En l’últim estudi, es va examinar l'efecte de la selecció contra greix dorsal a GIM constant sobre el patró d'expressió proteica hepàtica i la composició d'àcids grassos en fetge, múscul i greix subcutani . Es conclou, que el patró d'expressió proteica hepàtica en porcs està afectat per la selecció contra greix dorsal / La tesis se compone de tres estudios que se realizaron con el fin de disminuir el coste analítico que supone la determinación rutinaria de la grasa intramuscular (GIM) y del ácido oleico, así cómo de investigar los mecanismos biológicos de la deposición de la grasa. En el primer estudio se desarrolló un método analítico de alto rendimiento para la cuantificación del ácido oleíco en carne de cerdo usando un sistema de análisis por inyección de flujo basado en una espectrometría de masas con ionización por electrospray. El nuevo método, el cual permite una cuantificación rápida del contenido en oleico en muestras pequeñas, podría ser adecuado para la clasificación de cerdos y canales por su contenido en oleico. El segundo estudio evalúa el uso de indicadores lipídicos en suero cómo biomarcadores de la composición y contenido de la GIM y la grasa subcutánea a edades tempranas. Ninguno de los indicadores lipídicos investigados se recomiendan que se usen cómo un biomarcador precoz de la grasa. El último estudio examinó el efecto de la selección contra grasa dorsal a constante GIM sobre la expresión proteíca hepática, y la composición de ácidos grasos en hígado, músculo y grasa subcutánea. Se concluye que el patrón de expresión proteíca hepática en cerdos es afectada por la selección contra grasa dorsal. / The thesis comprises of three studies, with the aim at decreasing the cost of routinely intramuscular fat (IMF) and acid oleic determinations, as well as investigating the biological mechanisms of fat deposition. In the first study, it was developed a high-throughput analytical method for oleic fatty acid quantification in pork using a flow injection analysis system based on electrospray ionisation mass spectrometry. The new method, which allows for a rapid quantification of oleic content in small pork samples, may be used as a suitable method for ranking pigs and carcasses by oleic content. The second study assesses the usefulness of serum lipid indicators as early biomarkers of IMF and subcutaneous fat content and composition. None of the serum lipid indicators investigated is recommended to be used as an early biomarker of fatness. The last study examined the effect of selection against backfat thickness at constant IMF on hepatic protein expression and fatty acid composition in liver, muscle, and subcutaneous fat. It is concluded that hepatic protein expression pattern in pigs is affected by selection for decreased backfat thickness.

Bei Anwendung reversibler Betäubungsmethoden erfolgt die Tötung von Schlachttieren durch Blutentzug. Findet dieser nicht oder nicht in ausreichendem Maße statt, besteht die Gefahr, dass die Tiere ihre Wahrnehmungs- und Empfindungsfähigkeit wiedererlangen, bevor sie weiteren Verarbeitungsschritten zugeführt werden. Dies ist aus Tierschutzsicht keinesfalls hinnehmbar und steht im Widerspruch sowohl zum Tierschutzschlachtrecht, als auch zu Verbrauchererwartungen im Hinblick auf einen tierschutzgerechten Schlachtablauf. Es ist deshalb dringend erforderlich den Todeseintritt jedes Einzeltieres zu verifizieren. Dies kann durch direkte Kontrolle der Schlachttiere (klinische Untersuchung, Prüfung der Hirnstammreflexe) nach Eintritt des Todes erfolgen oder bereits frühzeitiger, über eine Erfassung von Parametern, die eine Aussage über die Wahrscheinlichkeit des kurz bevorstehenden Todeseintritts erlauben (TROEGER 2011). Hierfür eignet sich insbesondere die Stichblutmenge, bzw. die Blutflussrate, da ab einer bestimmten Blutmenge pro Zeiteinheit vom kurz bevorstehenden Tod des Tieres ausgegangen werden kann (TROEGER 2010). Zielsetzung dieser Arbeit war zum einen, ein geeignetes Messsystem zur Erfassung des Entbluteverlaufs zu finden und dieses in das Stechkarussell zu integrieren, zum anderen sollte der Zusammenhang zwischen Stichblutmengenanstieg und Todeseintritt der Tiere untersucht werden. In einem ersten Schritt wurden vier verschiedene Messsysteme zur Erfassung des Entbluteverlaufs unter Zuhilfenahme eines Prototyps geprüft: Stichblutwaage (Fa. Bizerba), Füllstandsmesssonde (Fa. Sick), Infrarotkamera „thermoIMAGER TIM“ (Fa. Micro-Epsilon) und Infrarotsensoren „thermoMETER CSmicro“ (Fa. Micro-Epsilon). Als Messparameter und Maß für die Qualität der Entblutung bzw. des Entblutestichs, wurde die Steigung des Blutanstiegs im Blutauffangbehälter verwendet. Das Messsystem „Infrarotsensoren“ erwies sich als am besten geeignetes System und wurde nachfolgend in die Stechkarussellanlage des Partnerschlachthofes integriert und der Messvorgang automatisiert. Um den Zusammenhang zwischen Stichblutmengenanstieg und Todeseintritt der Schweine auf der Nachentblutestrecke zu untersuchen, wurde der Entbluteverlauf in den ersten Sekunden nach dem Stich sowohl mit dem Prototyp (Messsystem Waage) als auch mit dem integrierten IR-Sensor-Messsystem bei einer Stichprobe von 1034 (Prototyp) bzw. 1500 (integriertes System) Schweinen erfasst und anschließend der Eintritt des Hirntodes der Tiere klinisch überprüft (u.a. Untersuchung der Hirnstammreflexe). Im Rahmen eines Vorversuchs wurde eine Status quo-Erhebung von Stichblutmenge- und anstieg durchgeführt und die ersten fünf Sekunden nach dem Entblutestich als geeigneter Messzeitraum festgelegt. Es konnte gezeigt werden, dass der Anstieg der Entblutekurve in diesem Zeitraum annähernd linear verläuft, unabhängig von Lebendgewicht und Geschlecht der Tiere ist, und zudem eine gewisse Voraussage über den weiteren Verlauf der Entblutung bzw. die am Ende der Entblutung absolut entzogene Blutmenge zulässt. In der Hauptuntersuchung waren bei keinem Tier deutliche Anzeichen für Empfindungs- und Wahrnehmungsvermögen (gerichtete Augenbewegungen, Vokalisation) vorhanden. 3,6 Prozent (Prototyp-Untersuchung) bzw. 3,7 Prozent (integriertes IR-Sensor-Messsystem) der Tiere zeigten jedoch bei der Verifizierung des Todeseintritts noch bzw. wieder Reaktionen, die zumindest auf eine gewisse (Rest-)Hirnfunktion hindeuteten. Ein signifikanter Zusammenhang zwischen Steigung der Entblutekurve und nachfolgendem Todeseintritt der Tiere konnte weder in der Untersuchung mit dem Prototyp, noch in der Untersuchung mit dem integrierten IR-Sensor-Messsystem dargestellt werden. Die Ursache dafür wird in einer Beeinflussung der Ergebnisse durch tierindividuell unterschiedliche Betäubungstiefen vermutet (irreversibel betäubte Tiere, deren Entblutekurven eine geringe Steigung aufwiesen, die aber trotzdem keine Reaktionen auf der Nachentblutestrecke zeigten). Im Rahmen der vorliegenden Arbeit wurde ein vollständig automatisiertes, mit herkömmlichen Stechkarussellanlagen kompatibles, Entblutekontrollsystem auf Grundlage der Infrarotsensor-Technik entwickelt. Durch die Fokussierung auf die ersten fünf Sekunden nach Setzen des Entblutestichs, ist das Ergebnis bereits verfügbar, wenn sich die Tiere noch in der Reichweite des Stechpersonals befinden, wodurch eine sofortige Nachbearbeitung betroffener Schweine, ohne zusätzlichen Personaleinsatz, ermöglicht wird. Weiterhin erlaubt das berührungslos arbeitende System eine Einzeltierkontrolle, inklusive automatischer Dokumentation der Entblutedaten, bei der sowohl unzureichend als auch versehentlich überhaupt nicht entblutete Schweine erkannt werden. Die Entwicklung des automatisierten Entblutekontrollsystems trägt dazu bei, den Tierschutz bei der Schweineschlachtung zu verbessern und gesetzliche Vorgaben sowie Verbrauchererwartungen im Hinblick auf tierschutzgerechte Fleischgewinnung als Teil der Lebensmittelqualität zu erfüllen.

2012年總統大選，民進黨的「三隻小豬」運動，堪稱是台灣選舉史上前所未見的造勢動員模式，此一「大事件」甚至破天荒，在2016年總統大選繼續沿用，因此本研究聚焦： 　　一、「三隻小豬」之事件發展，起源於台南三胞胎孩童把存在小豬撲滿裡的零錢，捐獻給要參選2012年總統的蔡英文，竟然在民進黨總統大選過程中，成為競選過程的「大事件」。二、「三隻小豬」之策略形成，民進黨如何運用這個「綠營最有效的募款工具」，在競選過程中，募得高達2.012億台幣的政治獻金。三、「三隻小豬」之媒體評論，以東森新聞報導為研究文本，2012選戰中，報導三隻小豬的則數，是平安福的將近四倍之多。三隻小豬，讓民進黨獲得的免費廣告效益，估計在10至20億台幣之間。 本研究者因為職務之故，能貼身採訪蔡英文陣營，因此採用「參與觀察、深度訪談」兩種研究方法，獲得第一手的訊息資料，再就東森新聞選舉過程中所報導「蔡英文」和「三隻小豬」的97篇相關文稿進行「內容分析」。 根據卡方檢定和ANOVA檢定的分析結果，本研究發現在蔡英文競選過程中，有三項值得觀察的顯著差異。並歸納出「三隻小豬」運動，此一大事件，具備不同於以往選舉的六大特色，包括：創新性、象徵性、互動性、在地性、參與性、持續性等。 / In the 2012 presidential election, The DPP’s Three Little Pigs campaign was so called the history of Taiwan's unprecedented mobilization election campaign. Four years later, in the 2016 presidential election, this “Mega Event” is to be continued, so this study highlights: First, the "Three Little Pigs" event that originated in Tainan, triplets’ children save money in a piggy bank, they donated the changes to the 2012 presidential candidate Tsai Ing-wen, set off political waves in the DPP election process unexpected. Second, how the "Three Little Pigs" policy formed, DPP proper use of this "come out of the gift," during the campaign, they raised up to NT$ 201.2 million in political contributions. Three Little Pigs can be described as the most effective fund-raising tool for the Green Camp. Third, the media covering regarding "Three Little Pigs" campaign, take the ETTV new scripts as study texts, during the 2012 election campaign, the number of covering stories in the Three Little Pigs is four times more than Ma Ying-jeou’s lucky charm. The DPP obtained about NT$ 1 to 2 billion free advertising effectiveness via Three Little Pigs movement. It is because of the researchers’ position; the researcher was able to interview Tsai camp closely. This research adopted "participant observation, in-depth interviews," these two methods, to obtain first-hand information and message. The researcher did "content analysis", to analyze 97 ETTV news stories regarding to "Tsai Ing-wen" and "The Three Little Pigs," in the presidential election. According to the analysis results of the chi-square test and ANOVA test, this study found that when Tsai Ing-wen was running for presidential campaign, there are three significant differences worth observing. Meanwhile, to conclude "The Three Little Pigs" mega event campaign, there are six characteristics different from previous elections, including: innovation, symbolic, interaction, localization, participation, sustainability and so on.

Novelty of the research: 1. Using pure and cross breeding methods competitive genotype of Lithuanian White pig was formed. 2. Method of mixed linear model multivariate analysis was used and heritability of pig productive traits was evaluated in one farm conditions. 3. Genetic evaluation of Lithuanian White breed structure – boars’ lines and sows’ families- was performed as well as their productive traits correlations were determined for the first time in country. 4. For the first time in Lithuanian pig husbandry computerized method for determination of „muscle eye“ area was used. Practical meaning of the work: Using advantages of pure breeding and applying Large White breed „blood infusion“ was created consolidated meat genotype of Lithuanian White pig with high heritability of muscularity, which is used for genetic improvement in other Lithuanian White pig breed farms. At the moment 90 % of best BLUP method evaluated Lithuanian White pig breed boars and sows are kept in UAB „Berka“.

The Results of Survey. During the acclimatization process fatten features of C and D lines pigs offspring are changing to the right side. But differences are not statistically trusted. During the acclimatization process fleshy features of C and D lines pigs’ offspring practically did not change. Trusted difference in D line estimated only to carcass side length (cm), which declined 3.9 cm (p<0.001), or in C line to carcass side length (p<0.005), which shorten pro rata 5.2 cm and 3.63 cm comparing with imported pigs offspring results. Trusted differences are not estimated to the remainder rates of fleshy features. That fleshy features did not change during the acclimatization process is seen from phenotipical estimation results. Fat thickness of C line pigs pedigree get – at 1 point rise 1.84 mm (p<0.005), or fat thickness of D line pedigree get – at 1 point even decrease 0.57 mm (p<0.005), comparing with imported pedigree get. During acclimatization process reproductive features C and D line sow practically did not change, only milkyness and percentage of piglets preservation from generation to generations improved. C line sow milkyness increased 10.68 kg (p<0.005), or D line sow 13.01 kg (p<0.001). Percentage of piglets preservation increased 7 % (p<0.025) in C line and 5.69 % (p<0.050) in D line. During acclimatization process time from piglet weaning till the first insemination is shorten 1.02 and 2.14 day (p<0.025) pro rata in C line F1 and F2 generations. But this time... [to full text]

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The broad objective of the study was to determine feeding behaviour and gut health of pigs fed different fibres at varying inclusion levels. Maize cob, maize stover, sunflower hulls, veld grass, sawdust, lucerne and dried citrus pulp were used in growing and finishing pig diets to provide a wide range of physicochemical properties. Time spent eating, drinking, lying down, sitting/standing and other activities was observed using video cameras. Blood samples were collected at the end of the trial for both growing and finishing pigs for analysis of glycated haemoglobin, albumin, globulin, total protein, creatine kinase, urea and uric acid. Intestinal segments were collected at the end of trial for growing pigs to determine mucosal architecture of the intestines. Digestible energy (DE), bulk density (BD), acid detergent fibre (ADF) and water holding capacity (WHC) were the most important variables predicting time spent on different behavioural activities in growing pigs (P < 0.001). Water holding capacity, neutral detergent fibre (NDF) and ADF were the most important variables involved in predicting time spent on different behavioural activities in finishing pigs (P < 0.001). Physicochemical properties influenced time spent on different behavioural activities and they provided relationships with time spent on different behavioural activities in both growing and finishing pigs. Glycated haemoglobin, albumin, globulin, total protein and uric acid were factors that influenced time spent eating in growing pigs (P < 0.05). In finishing pigs, only serum total protein was selected as the best predictor variable influencing time spent eating (P < 0.05). The blood metabolites were correlated with time spent eating and drinking. They provided threshold values with time spent eating and drinking by pig. Hence, they can also be used as potential biomarkers that modulate neuronal pathways which reduce time spent eating and drinking. In this study, bulk density (BD) and NDF were the best predictor variables influencing villi height (VH) and apparent villi surface area (AVSA) in pigs (P < 0.05). Grouped pigs fed fibrous diet spent more time eating, lying down, standing, walking and fighting (P < 0.05). Skin lesions appeared the most on neck and shoulder region followed by chest, stomach and hind leg region, and finally head region (P < 0.05). Fibrous diet did not reduce aggressive behaviours, rather aggressive behaviours emanated out of frustration when queuing at the feeder. It was concluded that physicochemical properties of fibrous diets and nutritionally-related blood metabolites influence feeding behaviour. Mucosal architecture was also influenced by physicochemical properties of the fibrous diets. / Ph.D. University of KwaZulu-Natal, Pietermaritzburg 2013.

Escherichia coli diarrhoea is the most important source of mortality in piglets. The most frequently isolated strain in enterotoxigenic E. coli diarrhoea is F4ab/ac. Recent studies in South Africa reported non-fimbrial strains such as PAA and EAST-1 to be prevalent. The objective of the study was to determine whether there are breed differences among pigs with respect to E. coli adhesion phenotypes and correlate them to polymorphisms at selected candidate genes in the South African population. A total of 225 pigs aged 3-12 weeks of the imported (Large White, Landrace and Duroc), local and crossbreds, were sampled from the Eastern Cape and Limpopo provinces of South Africa and genotyped for PCR-RFLP polymorphisms at four candidate genes associated with E. coli F4ab/ac resistance/susceptibility. These genes were Mucin 4 (MUC4), Mucin 13, (MUC13), Mucin 20 (MUC20) and Transferrin Receptor (TFRC). The TFRC and MUC13 genes were less polymorphic, the C allele was close to fixation and the homozygous CC genotype was the most frequent in all three pig populations. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for the TFRC locus. The g.8227G>C polymorphism in MUC4 segregated in all three breeds and the marker was moderately polymorphic. There was a significant difference (P <0.05) in genotypic distribution amongst breeds for MUC4.The g.191C>T polymorphism in MUC20 segregated in the local and crossbred pigs and was close to fixation in the imported pigs. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for MUC20, which was moderately polymorphic. There was a reduction in heterozygosity in both the TFRC and MUC13 loci, although MUC4 and MUC20 genes had higher heterozygosity levels. The MUC4 gene had a negative FIS value, indicating outbreeding at this locus. The MUC20, MUC13 and TFRC genes had a positive FIS value, indicating inbreeding at these loci. Overall, the studied population was outbred. Imported pigs in TFRC and MUC20 deviated from Hardy-Weinberg equilibrium (HWE). All breeds were in HWE at the MUC4 and MUC13 genes. There was no linkage disequilibrium observed amongst the analysed loci. iv A total of 109 piglets of three breeds (Large White, indigenous and crossbred) aged 3-5 weeks, were investigated for the susceptibility to E. coli F4, PAA strains and EAST-1 toxin. Adhesion tests were conducted on pig intestinal cells, which were viewed under a phase contrast microscope. Three phenotypes were identified as, adhesive, weakly adhesive and non-adhesive. There was a significant association (P <0.05) between breed and level of adherence of the F4 and PAA strains. Highest frequencies of adhesion phenotypes were observed in the indigenous pigs for both F4 and PAA E. coli strains. Large White pigs had the lowest frequency of non-adhesion in F4 and PAA E. coli strains. The F4 strain had a higher (P <0.05) level of adherence compared to PAA and EAST-1 in Large White pigs. Age of pigs had a significant effect on the level of E. coli adherence in indigenous and crossbred pigs (P <0.05). Adhesion of F4 and EAST-1 was higher in weaned indigenous and crossbred pigs, respectively, than in suckling piglets. There was no significant difference between F4 adhesion and the genotypes at all four candidate genes genotypes. The study showed that both imported and local pig populations carry receptors and are susceptible to F4, PAA and EAST-1 E. coli infections. Indigenous pigs were less susceptible than Large White to E. coli infection. Although polymorphic and segregating in the populations, the MUC4 g.8227G>C and MUC20 g.191C>T mutations were not associated with the adhesion phenotypes and cannot be used in the selection of susceptible animals. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.