No description available.

No description available.

<p>The objective of this thesis was to investigate the effect of dietary enzymatically treated yeast (ETY) in weanling pigs and evaluate the effect of ETY in broiler chickens during a coccidia challenge. Two studies were carried out to investigate this objective.</p> <p>The first experiment examined the effect of ETY on the growth performance, nutrient digestibility, immune response, and gut health of weanling pigs. A total of 192 weanling pigs (6.0 ± 1.04 kg) were allocated to 4 corn, soybean-based diets with increasing concentrations of ETY (0, 1, 2, or 4 g/kg) for a 43-d trial. There were 8 replicate pens (4 replicate pens per sex) and 6 pigs per replicate for each dietary treatment. The experiment was set up as a randomized complete block design. Dietary ETY supplementation did not affect the growth performance of weanling pigs. The ATTD of neutral detergent fiber (NDF) linearly increased (P < 0.05) at d 28. The concentrations of serum antioxidant and antibody markers increased (P < 0.05) from d 14 to d 43; a linear increase (P < 0.05) in catalase was observed on d 14 with increasing ETY supplementation in the diets. The inclusion of ETY in the diet did not affect the mRNA abundance of anti-inflammatory markers in the ileal mucosa of pigs but increased (P < 0.01) glutathione peroxidase 4. Ileal villus height (VH) and villus height to crypt depth (VH:CD) ratio were greater (P < 0.05) in pigs fed ETY supplemented diets relative to control pigs. However, jejunal VH and the VH:CD ratio was not affected by ETY inclusion in the diet. Pigs fed diets with increasing ETY levels had higher (P < 0.05) ileal digesta butyrate concentration relative to control pigs, but not propionate or acetate. </p> <p>The second experiment examined the effect of ETY on the growth performance, nutrient digestibility, and intestinal health of broiler chickens during a coccidia challenge. From d 1 to 14 post hatching, 480 broiler chickens (49.9 ± 3.95 g) were allocated to 3 corn-soybean meal-based diets with increasing concentrations of ETY (0, 1, or 2 g/kg). There were 16 replicate cages and 10 birds per cage. The experiment was designed as a randomized complete block design with body weight (BW) used as a blocking factor. On d 14 post hatching, the birds were combined and re-randomized within each of the 0, 1, or 2 ETY g/kg experimental diets. Following this, the number of birds was reduced to 8 birds per cage with 8 replicate cages. Each of the 3 diet groups was split into a challenge or no-challenge group. This resulted in a 3 × 2 factorial arrangement of treatments with 3 experimental diets and 2 challenge states. The BW ratio before re-randomization was maintained across all treatments during the reallotment. On d 15 post hatching, the birds in the challenge group were orally gavaged with 1 mL solution containing 25,000, 25,000, and 125,000 oocysts of E. maxima, E. tenella, and E. acervulina, respectively. The birds belonging to the no-challenge group were orally gavaged with 1 mL phosphate buffered saline. Data were analyzed using the MIXED procedure of SAS, and polynomial contrasts were used to estimate the linear and quadratic effects of ETY. The coccidia challenge (CC) decreased (P < 0.01) the BW gain, feed intake, and G:F of broiler chickens from d 14 to 21. Increasing supplementation of dietary ETY improved (P < 0.05) the G:F of birds. Also, the CC reduced (P < 0.01) the apparent total tract utilization of dry matter (DM), nitrogen (N) and gross energy (GE). The CC reduced (P < 0.01) the apparent metabolizable energy (AME) and the nitrogen corrected apparent metabolizable energy (AMEn) of diets fed to broiler chickens. On d 21, dietary ETY linearly increased (P < 0.01) the apparent ileal digestibility of DM, N, and GE in broiler chickens. The CC increased (P < 0.01) the mRNA gene expression of TNFα, IL-1β, IL-10, and IL-6. There was a tendency (P < 0.1) for ETY to reduce IL-1β expression in broiler chickens on d 21. Additionally, ETY supplementation increased (P < 0.05) the gene expression of occludin in the ceca of broiler chickens but not claudin 1. Serum catalase increased (P < 0.05) with increasing supplementation of dietary ETY in broiler chickens on d 21. Dietary ETY linearly increased (P < 0.05) the ileal villus height to crypt depth ratio and ileal goblet cell count and density in broiler chickens. The ileal and excreta oocyst counts decreased (P < 0.01) with increasing supplementation of dietary ETY in coccidia-challenged broiler chickens on d 21. </p> <p>In summary, ETY inclusion in diets of weanling pigs partially reduced reactive oxygen species damage and enhanced intestinal health without negatively affecting growth performance. Hence, ETY could be favorable in attenuating some of the deleterious effects of post-weaning stress in weanling pigs. Dietary ETY also reduced oxidative damage, improved growth performance, enhanced nutrient utilization, and augmented intestinal development in broiler chickens. However, the inclusion of ETY did not mitigate the adverse effects of a coccidia challenge in broiler chickens. Therefore, further studies may be necessary to investigate the prospect of ETY as a dietary strategy for combating coccidiosis.</p> <p><br></p>

No / Gas chromatography (GC), GC-mass spectrometry (GC-MS) and GC-combustion-isotope ratio MS (GC-C-IRMS) analyses of absorbed and surface lipid residues preserved in potsherds were used to explore the extent of pig product processing exploitation in the later British Neolithic Grooved Ware tradition. Assessments were made regarding whether porcine lipids were associated with specific Grooved Ware traits, i.e. decoration, substyle, geographical area and type of site. Two hundred and twenty-two Grooved Ware potsherds were analysed, 70% of which contained lipid concentrations considered significant (>5 μg g−1). All the lipid residues were dominated by animal fats, although plant and beeswax were also detected in a small number of extracts. δ13C values of the major fatty acid components of degraded animal fats (C16:0 and C18:0) were determined for 126 extracts and used to assign ruminant or porcine origins to the residues; 16% of these were found to have a predominantly porcine isotope signature. Statistical associations with pig exploitation were shown to exist with substyle, geographical area and site type, whereas, no relationship was seen between decoration and the type of commodity processed. Intact triacylglycerols were preserved in 19% of the sherds; half of these had distributions consistent with the identifications based on δ13C values, the remainder differed either due to the presence of mixed commodities or because lower molecular weight homologues had been lost due to degradation. In addition to the detection of pig exploitation, results from lipid residue analysis showed a good correlation with faunal assemblages, suggesting that stable isotope analysis may be used as a proxy for animal exploitation at sites where bones have not survived.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Joel M. DeRouchey / Steven S. Dritz / A total of 9,979 pigs were used in 11 experiments to quantify production responses under field conditions in growing pigs to PCV2 vaccination, biofuel co-products and dietary supplemental enzymes. Experiments 1 and 2 were conducted to determine the efficacy of a commercial 2-dose Porcine Circovirus Type 2 (PCV2) vaccine. Growth performance and mortality (P < 0.05) of vaccinated pigs improved compared to non-vaccinated pigs in both experiments with the vaccine causing a greater increase in ADG in vaccinated barrows than vaccinated gilts in Exp. 2. Experiment 3 compared the efficacy of 1-dose and 2-dose commercial PCV2 vaccines, where vaccinated pigs had greater ADG (P < 0.05) than vaccinated pigs regardless of vaccine type. The 2-dose group was heavier (P < 0.05) than the control group while the 1-dose group was intermediate. Therefore, PCV2 vaccines were efficacious under field conditions. Experiments 4, 5, and 6 were conducted to evaluate de-oiled corn dried distillers grains with solubles (dDGS) in grow-finish pigs. In Exp. 4, analyzed CP and AA content were higher, but lysine digestibility and energy content were lower in dDGS than traditional dried distillers grains with solubles (DDGS). In Exp. 5, 0 to 30% dDGS in nursery diets did not affect growth performance (P > 0.52). In Exp. 6, 0 to 30% dDGS reduced (linear; P < 0.01) ADG and ADFI, tended to improve (linear; P > 0.07) G:F, decreased (linear; P < 0.01) carcass yield, and increased (linear; P < 0.01) fat iodine values. Experiment 7 was conducted to determine the AA digestibility and energy concentration of novel high-CP distillers co-products from corn (HPC-DDG) and sorghum (HPS-DDGS). Digestibility of AA was higher for HPC-DDG but lower in HPS-DDGS than traditional DDGS. Both co-products had lower energy than traditional DDGS. Finally, Exp. 8, 9, 10, and 11 were used in a meta-analysis to evaluate supplementary dietary enzymes in pigs. Supplemental enzymes, alone or in combination, did not improve grow-finish pig performance (P > 0.58) regardless of dietary DDGS level. In conclusion, these experiments provide important empirical data to quantify production responses of various interventions and dietary ingredients under actual field conditions.

Thesis (MPhil (Animal Sciences. Livestock Industry Management: Pig Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: This mini-thesis describes the pig industry in South Africa which consists of a commercial intensive sector and an extensive sector that is also known as the small scale sector. Challenges in such as, marketing, feed, housing and genetics of small scale farmers are discussed. The objective of this study is to identify the problems experienced by the emerging/small scale pig farmers and to benchmark the production parameters of these farmers. Data was collected using questionnaires, telephone and site visits to farms/projects. The data collection was grouped into descriptions of small scale piggeries, feeding strategies, management programs, production parameters, regional constraints, marketing, comparisons between stud and commercial piggeries. The results were arranged into the following manner: general, regional constraints, description of small scale piggery facilities, feeding strategies of small scale farmers, management programs in small scale piggeries, production parameters of small scale piggeries in the Limpopo province, production parameters of stud and commercial piggeries, and the management strategy in a commercial piggery. Those piggeries having 5-30 sow units were interviewed. Results indicate that small scale farmers were found not to be sustainable in their production. The small scale farmers have no understanding of the pig industry, genetics and breeding of pigs, feeding strategies, and marketing channels for pigs. Typical problems experienced are: marketing is only done once or twice a year and not regularly as with any commercial piggery – a main problem identified here was access to the formal market. Typical production problems experienced were long farrowing intervals, small litter sizes, late weaning periods and low weaning percentages. This was attributed not only to mismanagement but also to bad infrastructure. Small scale piggeries typically have low cost sty’s that have inadequate floors, walls, roofing and very few of the piggeries has sufficient fresh water. Another problem experienced was poor growth which could be directly linked to the nutrition of the pigs. Most of the feed fed consisted of kitchen waste as balanced diets were perceived to be too expensive whilst access to suppliers, and transport (of both feed and pigs off to market) was generally lacking. Another major problem identified by the producers was insufficient scientific help from Government. Most producers also mentioned that they would welcome a mentorship program and help with the marketing and sourcing of funds. None the less, the pig owners all indicated that they wish to continue farming with pigs and that with the right help, they would be able to be successful. / AFRIKAANSE OPSOMMING: Hierdie werkstuk beskryf die vark industrie in Suid-Afrika wat bestaan uit ‘n kommersiële intensiewe en ekstensiewe sektor wat ook bekend staan as die klein-skaal sektor. Uitdagings soos bemarking, voer, behuising en genetika van klein-skaalse boere word bespreek. Die doel van die studie is om die probleme te identifiseer wat ervaar word deur die opkomende/klein-skaalse boere asook om die produksie-parameters van die boere te bepaal. Data was versamel deur middel van vraelyste, telefoonoproepe asook besoeke aan die boere/projekte. Die dataversameling was op verdeel in beskrywings van klein-skaalse vark eenhede, voerstrategieë, bestuursprogramme, produksie-parameters, distriksbeperkings, bemarking, en vergelykings tussen stoet- en kommersiële-eenhede. Die resultate was gesorteer op die volgende manier: algemeen, distriksbeperkings, beskrywing van klein-skaalse varkeenhede, produksie-parameters van klein-skaalse varkeenhede in die Limpopoprovinsie, produksieparameters van stoet- en kommersiële varkeenhede, en die bestuurstrategie in ’n kommersiële varkeenheid. Ondehoude is gevoer met dié eenhede wat tussen 5-30 soê het. Resultate wys dat klein-skaalse boere nie volhoubaar is in hul produksie nie. Die klein-skaalse boere het geen kennis van die vark bedryf, genetika en teel van varke, voerstrategieë en bemarking van varke nie. Tipiese probleme wat ervaar word is: bemarking word slegs een of twee keer per jaar gedoen en nie gereeld soos met kommersiële eenhede nie – die hoof probleem wat geïdentifiseer is die toegang tot die formele mark. Tipiese produksieprobleme wat hier geïdentifiseer is, was lang kraam intervalle, klein werpsel groottes, laat speenperiodes en lae speenpersentasies. Dit was as gevolg van nie net misbestuur nie, maar ook as gevolg van slegte infrastruktuur. Klein-skaalse vark eenhede het gewoontlik goedkoop varkhokke met onvoldoende bevloering, mure, en dakke en baie min van die eenhede het genoegsame vars water gehad. Nog ’n probleem wat ondervind is, was die slegte groei van die varke wat direk gekoppel kan word aan die voeding van die varke. Meeste van die voer het bestaan uit kombuisvullis omdat gebalanseerde rantsoene beskou was as te duur, terwyl daar oor die algemeen ’n te kort was aan toegang tot verskaffers en vervoer (van beide voer en varke na die mark). Nog ’n groot probleem wat geïdentifiseer is deur die produsente was dat daar ’n tekort is aan wetenskaplike hulp van die Regering. Meeste van die produsente het ook genoem dat hul ’n mentorskapprogram sal verwelkom asook hulp met bemarking en befondsing. Nie te min, die varkeienaars het almal aangetoon dat hul graag met die varkboerdery sou wil aangaan en dat met die regte hulp sou hul suksesvol kan wees.

Female reproductive performance is a critical component of sustainable pig production systems. There is abundant evidence of genetic variation in these traits among pig breeds. The aims of this study were to identify quantitative trait loci (QTL) affecting reproductive traits and to identify and characterise positional candidate gene(s) underlying the QTL. A Large White - Meishan F2 population was scanned for QTL with effects on reproductive traits. This analysis revealed 13 putative QTLs on seven different chromosomes with effects on five different traits: ovulation rate (OR), teat number (TN), prenatal survival (PS), total born alive (TBA) and litter size (LS). QTL for PS and LS on chromosome 8 were fine mapped and Secreted Phosphoprotein 1 (SPP1) confirmed as a candidate gene. A genome-wide association study was performed on a diverse population of different breeds and crosses lines, for reproductive traits including LS, TBA, number of stillborn piglets, and number of mummified piglets. Fourteen SNPs were found significantly associated with reproductive traits. The functional study of SPP1 examined the hypothesis that differences in foetal growth may be associated with the effectiveness of conceptus attachment, as measured by SPP1 expression. Patterns of SPP1 mRNA and protein expression in placental and uterine tissues supplying the smallest and a normal-sized foetus from the same uterus were examined in Large White-Landrace (LW-LR), Large White (LW) and Meishan (MS) females 40 and 45 of pregnancy. The smallest LW-LR foetuses tended to have a higher level of SPP1 mRNA in endometrium tissue compared to the normal-sized foetuses. However, placenta expression was higher in the normal-sized foetuses compared to the smallest ones. SPP1 protein levels in normal sized foetuses were significantly higher than in the smallest litter mates for all the tissues. Significantly higher levels of SPP1 mRNA and protein were found in MS compared to LW. In both breeds, significant differences between sizes were found in some tissues, with similar expression patterns in respect to size, for both mRNA and protein in endometrial tissues when compared to contemporary LW. In placenta, the direction of the expression differed between breeds, with a higher expression of mRNA and protein in the normal-sized MS foetuses and in the smallest sized LW foetuses. The comparison of SPP1 expression between different foetal sizes and different breeds revealed associations between breed, foetal size, and SPP1 protein, factors implicated in PS and LS. These results together with the genetic evidence indicate that the potential role of SPP1 in placental and foetal development merits further investigation.

<p style="text-align: justify; ">Glavni cilj ovog rada je bio da se razviju i optimizuju objektivni i merljivi&nbsp;indikatori biolo&scaron;kih rizika po bezbednost mesa trupova, kao i da se &ndash; na osnovu&nbsp;kvalitativne ocene rizika - objektivno sagledaju i uporede performanse glavnih strategija&nbsp;za upravljanje tim rizicima na klanicama za goveda i svinje.<br />Ispitan je potencijal haptoglobina goveda i svinja, podeljenih u grupe na osnovu&nbsp;njihove pred-istorije ili nalaza tokom inspekcije mesa, kao indikatora za njihovu rizičnu&nbsp;kategorizaciju pre klanja u pogledu prisustva patolo&scaron;kih lezija. Svaka životinja je bila&nbsp;podvrgnuta aktuelnoj zvaničnoj inspekciji mesa i određen je nivo haptoglobina u krvnom&nbsp;serumu. I u svinja i u goveda, srednje vrednosti koncentracije haptoglobina su bile&nbsp;značajno vi&scaron;e u grupama kod kojih su detektovane abnormalnosti u odnosu na grupe ovih&nbsp;životinja bez nađenih promena, ali takva korelacija nije utvrđena na nivou individualne<br />životinje. Studija je ukazala da određivanje srednjeg nivoa haptoglobina u grupa životinja&nbsp;namenjenih klanju može da služi kao dodatni, objektivni indikator op&scaron;te prihvatljivosti&nbsp;zdravstvenog statusa i/ili farme porekla životinja, u okviru analize informacija iz lanca&nbsp;hrane kao dela premortalne inspekcije. Ovo je važno zbog dono&scaron;enja odluke o&nbsp;sprovođenju pojednostavljene ili detaljnije postmortalne inspekcije određenih životinja ili&nbsp;grupa životinja na klanicama.&nbsp;U pogledu indikatora rizika od mikrobiolo&scaron;ke kontaminacije obrađenih goveđih&nbsp;trupova, ispitana je mogućnost kori&scaron;ćenja numeričke ocene vizuelne čistoće goveda pre&nbsp;klanja. Vizuelno je ocenjena čistoća kože goveda (na skali od 1 do 4), a zatim su na&nbsp;obrađenim trupovima određeni nivoi generičke mikrobiote i prisustvo Escherichia coli&nbsp;O157. Utvrđena je globalna korelacija između vizuelne čistoće kože i nivoa generičke&nbsp;mikrobiote na obrađenim trupovima, ali su se ti nivoi značajno razlikovali samo između&nbsp;trupova vrlo prljavih goveda (kategorija 4) i svih drugih manje prljavih ili čistih&nbsp;(kategorije 1, 2 i 3). U pogledu vizuelne čistoće goveda i prisustva Escherichia coli O157&nbsp;na obrađenim trupovima, jasna korelacija nije utvrđena. Potvrđena je opravdanost&nbsp;kori&scaron;ćenja sistema vizuelne ocene čistoće goveda i korisnost ove ocene kao jednog od&nbsp;indikatora nivoa rizika od mikrobiolo&scaron;ke kontaminacije obrađenih trupova u pogledu&nbsp;generičke mikrobiote.&nbsp;Takođe, ispitana je mogućnost kori&scaron;ćenja kvantitativnog odnosa između nivoa&nbsp;ulazne (na koži) i finalne (na obrađenim trupovima) mikrobiolo&scaron;ke kontaminacije kao&nbsp;potencijalnog indikatora za rizičnu kategorizaciju goveđih i svinjskih klanica u pogledu&nbsp;njihovih performansi u redukciji rizika od mikrobiolo&scaron;ke kontaminacije mesa. Na&nbsp;kožama i trupovima goveda i svinja su određeni nivoi generičke mikrobiote i prisustvo&nbsp;najznačajnijih patogena u lancu goveđeg (Escherichia coli O157) i svinjskog mesa&nbsp;(Salmonella). Rezultati su pokazali da je odnos statusa kože i obrađenog trupa u pogledu&nbsp;nivoa generičke mikrobiote precizniji i pouzdaniji u diferencijaciji performansi procesne&nbsp;higijene klanica, u poređenju sa zvaničnim aktuelnim kriterijumima procesne higijene&nbsp;navedenim u legislativi Evropske Unije. S druge strane, rezultati su ukazali da kori&scaron;ćenje&nbsp;prevalencije patogena kao parametra u karakterizaciji procesne higijene klanica nije&nbsp;korisno.&nbsp;Pored toga, upoređeni su potencijalni doprinosi glavnih dana&scaron;njih strategija u&nbsp;upravljanju biolo&scaron;kim rizicima za bezbednost mesa na klanicama za goveda i svinje -&nbsp;aktuelne inspekcije mesa i procesne higijene klanice - ukupnom osiguranju biolo&scaron;ke&nbsp;bezbednosti mesa. Kvalitativno su ocenjeni rizici po zdravlje ljudi od alimentarnih&nbsp;hazarda povezanih sa goveđim ili svinjskim mesom, koje je moguće kontrolisati jednom&nbsp;od ove dve strategije na klanicama. Poređenjem nivoa ocenjenih rizika, utvrđeno je da&nbsp;adekvatna procesna higijena danas značajno vi&scaron;e doprinosi ukupnoj biolo&scaron;koj&nbsp;bezbednosti mesa trupova goveda i svinja u odnosu na aktuelnu inspekciju mesa. Ipak, u&nbsp;globalnom sistemu bezbednosti mesa, obe navedene strategije moraju da imaju specifičnu&nbsp;ulogu, shodno oceni rizika od hazarda koje kontroli&scaron;u.&nbsp;Svekupno, ova studija je pružila naučnu osnovu za dalje unapređenje savremenog,&nbsp;longitudinalnog i integrisanog sistema biolo&scaron;ke bezbednosti goveđeg i svinjskog mesa,&nbsp;kao i za kori&scaron;ćenje nekih novih indikatora biolo&scaron;kih rizika u tom sistemu. Istovremeno,&nbsp;ukazala je i na potrebu i smer za dalja/dublja istraživanja za optimizaciju i&nbsp;implementacije tog modernog sistema i predloženih indikatora rizika u praksi.</p> / <p> The main aim of this work was to develop and optimize objective and measurable<br /> indicators of biological risks for the safety of carcass meat, and to - based on qualitative<br /> risk assessment - identify and objectively compare performances of the main risk<br /> management strategies in cattle and pig abattoirs.<br /> The potential of haptoglobin as an indicator of animal pre-slaughter risk<br /> classification regarding the presence of pathological lesions was investigated in cattle and<br /> pigs which were divided into groups, based on their pre-history or meat inspection<br /> findings. Each animal was subjected to the current official meat inspection and blood<br /> serum haptoglobin level determination. In both cattle and pigs, the mean haptoglobin<br /> concentrations were significantly higher in groups with abnormalities than in those<br /> without, but such a correlation was not been established at the level of individual animals.<br /> The study indicated that the mean haptoglobin level in groups of animals intended for<br /> slaughter can be used as an additional, objective indicator of general health status of<br /> animals and/or appropriateness of farm of their origin, when analysing the food chain<br /> information as a part of the ante-mortem inspection. This is important in deciding<br /> whether to perform simplified or detailed post-mortem inspection of certain animals or<br /> groups of animals at abattoirs.<br /> The numerical assessment of cattle cleanliness before slaughter was evaluated as a<br /> risk indicator of dressed beef carcasses&rsquo; microbial contamination. Cattle hide cleanliness<br /> was visually assessed (on a scale of 1 to 4) and levels of generic microbiota and<br /> occurrence of Escherichia coli O157 on dressed carcass were determined. A global<br /> correlation was found between the visual hide cleanliness and generic microbiota levels<br /> on dressed carcasses, but these levels significantly differed only between very dirty cattle<br /> (category 4) and all other less dirty or clean cattle (categories 1, 2 and 3). Regarding the<br /> visual cattle cleanliness and the presence of Escherichia coli O157 on dressed carcasses,<br /> a clear relationship was not determined. The validity of cattle cleanliness visual<br /> assessment system and usefulness of this as an indicator of risk of generic microbiota<br /> contamination of dressed carcasses was confirmed.<br /> Also, the quantitative relationship between the levels of incoming (hide/skin) and<br /> final (dressed carcasses) microbiological contamination was evaluated as an indicator for<br /> risk categorization of cattle and pig abattoirs in terms of their performances in reducing<br /> the risk of microbiological contamination of meat. Levels of generic microbiota and<br /> occurrence of the major pathogens in beef (Escherichia coli O157) and pork chain<br /> (Salmonella) were determined on hides/skins and dressed carcasses. The results showed<br /> that the ratio between generic microbiota levels on dressed carcasses and hides/skins is<br /> more precise and more reliable in the differentiation of process hygiene performances of<br /> abattoirs, compared to the official current process hygiene criteria laid down in the<br /> European Union legislation. On the other hand, the results indicated that the prevalence<br /> of pathogens is not useful as a parameter in the characterization of abattoir process<br /> hygiene.<br /> Additionally, potential contributions of the main current strategies in biological<br /> meat safety risk management in cattle and pig abattoirs - the current meat inspection and<br /> abattoir process hygiene - in ensuring the overall biological safety of meat were<br /> compared. Human health biological foodborne risks associated with beef or pork that can<br /> be controlled by one of the two strategies at abattoirs were qualitatively assessed.<br /> Comparing the levels of assessed risks, it was concluded that adequate process hygiene<br /> currently contributes significantly more to the overall biological safety of beef and pork<br /> VIII<br /> carcasses than current meat inspection. However, in the global meat safety assurance<br /> system, both of these strategies must have a specific role, according to the risk<br /> assessment of hazards which they individually control.<br /> Overall, this study has provided a scientific basis for the further development of<br /> contemporary, longitudinal and integrated risk management system for biological safety<br /> of beef and pork, as well as the use of some new indicators of biological risk in such a<br /> system. At the same time, it has indicated the needs and directions for further and more<br /> intensive research to optimize and implement that modern system and the proposed risk<br /> indicators in practice.</p>

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

Certaines stratégies alimentaires sont actuellement considérées pour remplacer l’usage des antimicrobiens dans les fermes porcines. Les objectifs de cette étude étaient d'évaluer l'effet de la granulométrie et de la texture des aliments sur les concentrations d'acides gras volatils intestinaux, la composition des populations pathogènes et commensales d’E. coli et sur les performances de croissance des porcs. Des porcs d'engraissement (n= 840) ont reçu l'une des six diètes suivantes: moulée texturée 500, 750 et 1250 µm et moulée cubée 500, 750 et 1250 µm. Le gain de poids a été mesuré à chaque changement de formulation de moulée. À l'abattoir, les contenus du caecum et du côlon de 165 porcs ont été échantillonnés pour le dénombrement des E. coli par PCR quantitatif (qPCR) et pour la quantification des AGV. Le gène yccT a été utilisé pour dénombrer les E. coli totaux. Une diminution du taux de conversion alimentaire a été associée avec la moulée cubée et/ou la moulée de 500 µm. Les concentrations d’acide propionique et butyrique, et ce tant au niveau du caecum que du côlon, étaient plus élevées chez les porcs recevant de la moulée texturée que chez ceux recevant de la moulée cubée. Du point de vue de la granulométrie, les concentrations caecales et du côlon d’acide butyrique étaient plus élevées chez les porcs alimentés avec de la moulée de 1250 µm que chez ceux recevant de la moulée de 500 µm. D'autre part, les niveaux intestinaux d’E. coli totaux étaient plus élevés pour les porcs nourris avec de la moulée cubée que pour ceux ayant reçu de la moulée texturée. Les résultats ont montré que la moulée texturée est associée à des performances de croissance plus faibles mais à des changements intestinaux favorables. / Natural approaches, such as dietary modifications, are now being considered to replace antimicrobials for the control of bacterial infections in pigs. The objectives of this study were to assess the effect of feed size and texture on intestinal Volatile fatty acids profiles and concentrations, E. coli populations, and on growth performance. Fattening pigs (n=840) received one of six different diets: mash feed 500, 750 and 1250 µm and pellet feed 500, 750 and 1250 µm. Weight gain of pigs was monitored for each diet formulation over the fattening period. At the slaughterhouse, caecal and colon contents from 165 pigs were sampled for enumeration of E. coli by quantitative PCR (qPCR) and for acetic, propionic and butyric acid quantification. The yccT gene was used to enumerate total E. coli. A decrease in feed conversion associated with pellet texture and/or 500 µm particle size was observed for each diet formulation. In addition, caecal and colon propionic acid concentrations and caecal and colon butyric acid concentrations were lower for pigs receiving pellet rather than mash feed. Moreover, caecal (p=0,0208) and colon (p=0,0006) butyric acid concentrations were higher for pigs receiving a feed with a 1250 µm rather than 500 µm particle size. For total E. coli enumeration, caecal (p=0,01) and colon (p=0,04) yccT gene copies were higher for pigs receiving pellet rather than for those receiving mash feed. Taken together, results showed that mash feed is associated with favourable intestinal changes (VFA levels) and with a reduction of E. coli in the pig.