O processo de abate de suínos envolve diversas operações que podem influenciar a qualidade microbiológica das carcaças. Sendo assim, a compreensão do processo de abate sobre os aspectos microbiológicos é necessário para a implementação e avaliação de pontos críticos de controle. O controle microbiológico do processo de abate deve envolver a determinação da prevalência de patógenos e dos níveis de microrganismos indicadores de qualidade e higiene. Assim, este estudo teve como objetivo analisar a influência das etapas de abate sobre os níveis microbiológicos das carcaças. Adicionalmente, avaliar se existe correlação entre a presença de patógenos (Salmonella spp. e Listeria monocytogenes) e microrganismos indicadores (aeróbios mesófilos, coliformes totais, Escherichia coli e Enterobacteriaceae). Uma alta soroprevalência de Salmonella foi encontrada nos suínos ao início do abate (57,49 %). Enquanto a prevalência de Salmonella nas carcaças na etapa inicial do abate foi de 26,67 % e na etapa final de 1,11 %. L. monocytogenes somente foi detectada após as etapas de lavagem final e resfriamento, com uma prevalência de 21,11 e 8,89 %, respectivamente. Os níveis de aeróbios mesófilos, Enterobacteriaceae, coliformes totais e Escherichia coli no início do processo de abate foram de 4,25 ± 0,37; 1,25 ± 0,38; 1,10 ± 0,35 e 0,86 ± 0,36 log UFC/cm2, respectivamente. Já no final do processo os níveis foram menores variando entre 0,16 a 2,70 log UFC/cm2. A etapa que resultou na maior redução microbiana foi a escaldagem. A depiladeira é uma etapa crítica, onde os níveis de contaminação aumentaram significativamente em relação ao início do processo (p < 0,05). A evisceração não se mostrou uma etapa crítica sobre o aumento dos níveis microbianos. Contrariamente, a etapa de lavagem final, apresentou um aumento significativo (p < 0,05) sobre os níveis de aeróbios mesófilos, coliformes totais, E. coli e enterobactérias (0,30; 0,36; 0,27 e 0,42 log UFC/cm2, respectivamente), Salmonella spp. e L. monocytogenes. O resfriamento das carcaças contribui significativamente para a redução dos níveis microbiológicos, trazendo-os para níveis inferiores a todas as etapas do processo, exceto para a etapa de escaldagem. Dos quatro grupos de indicadores avaliados, nenhum apresentou correlação com a presença de Salmonella spp. e L. monocytogenes (p <0,05). Os resultados obtidos indicam a existência de etapas da cadeia de produção que se apresentam como críticas do ponto de vista sanitário, o que implica na necessidade de implementação de ações no processo para reduzir os níveis microbiológicos. / The pig slaughter process involve different steps that can influence the microbiological quality of carcasses. At this, the understanding of the slaughter process on the microbiological aspects is necessary for the implementation and evaluation of critical control points. The microbiological control of the slaughter process should involve the evaluation of pathogens prevalence and levels of quality and hygiene indicator microorganisms. This study aimed at investigating the influence of steps slaughter process on the microbiological levels of pig carcasses, and evaluate if there is correlation between pathogens (Salmonella spp. and Listeria monocytogenes) and indicators (aerobic mesophilic counts, total coliforms, Escherichia coli and Enterobacteriaceae) microorganisms. A high Salmonella soroprevalence in pigs were founded before the slaughter (57.49 %). While the Salmonella prevalence in carcasses at the initial stage of the slaughter was 26.67 % and in the final stage 1.11 %, L. monocytogenes was detected only in the final washing and cooling steps, with a prevalence of 21.11 and 8.89 %, respectively. The aerobic mesophilic counts, Enterobacteriaceae, total coliforms and E. coli levels in initial steps of slaughter process were 4.25 ± 0.37; 1.25 ± 0.38; 1.10 ± 0.35 and 0.86 ± 0.36, respectively. At the end of slaughter process the results were lower (ranging from 0.16 at 2.70 log CFU/cm2). The step that most reduced microbiological levels was the scalding. The dehairing was a critical step that led to a significant increase of microorganisms levels in the process (p < 0.05). The evisceration not proved to be a critical step on the increase of microbial levels, differently of the final washing, which showed significant increases (p < 0.05) over the levels of aerobic counts, total coliforms, E. coli and enterobacterias (0.30; 0.36; 0.27 and 0.42 log respectively) and Salmonella spp. and L. monocytogenes. The chilling contributes significantly to the reduction of microbiological levels of carcasses, bringing them to levels below the all process stages, with the exception of scalding. No correlation between the hygiene indicator microorganisms used and presence of Salmonella spp. and L. monocytogenes were obtained (p < 0.05). The results show that steps in the process are critical to the sanitary profile, which implies the need to implement actions in the process to reducing the microbiological levels.

O processo de abate de suínos envolve diversas operações que podem influenciar a qualidade microbiológica das carcaças. Sendo assim, a compreensão do processo de abate sobre os aspectos microbiológicos é necessário para a implementação e avaliação de pontos críticos de controle. O controle microbiológico do processo de abate deve envolver a determinação da prevalência de patógenos e dos níveis de microrganismos indicadores de qualidade e higiene. Assim, este estudo teve como objetivo analisar a influência das etapas de abate sobre os níveis microbiológicos das carcaças. Adicionalmente, avaliar se existe correlação entre a presença de patógenos (Salmonella spp. e Listeria monocytogenes) e microrganismos indicadores (aeróbios mesófilos, coliformes totais, Escherichia coli e Enterobacteriaceae). Uma alta soroprevalência de Salmonella foi encontrada nos suínos ao início do abate (57,49 %). Enquanto a prevalência de Salmonella nas carcaças na etapa inicial do abate foi de 26,67 % e na etapa final de 1,11 %. L. monocytogenes somente foi detectada após as etapas de lavagem final e resfriamento, com uma prevalência de 21,11 e 8,89 %, respectivamente. Os níveis de aeróbios mesófilos, Enterobacteriaceae, coliformes totais e Escherichia coli no início do processo de abate foram de 4,25 ± 0,37; 1,25 ± 0,38; 1,10 ± 0,35 e 0,86 ± 0,36 log UFC/cm2, respectivamente. Já no final do processo os níveis foram menores variando entre 0,16 a 2,70 log UFC/cm2. A etapa que resultou na maior redução microbiana foi a escaldagem. A depiladeira é uma etapa crítica, onde os níveis de contaminação aumentaram significativamente em relação ao início do processo (p < 0,05). A evisceração não se mostrou uma etapa crítica sobre o aumento dos níveis microbianos. Contrariamente, a etapa de lavagem final, apresentou um aumento significativo (p < 0,05) sobre os níveis de aeróbios mesófilos, coliformes totais, E. coli e enterobactérias (0,30; 0,36; 0,27 e 0,42 log UFC/cm2, respectivamente), Salmonella spp. e L. monocytogenes. O resfriamento das carcaças contribui significativamente para a redução dos níveis microbiológicos, trazendo-os para níveis inferiores a todas as etapas do processo, exceto para a etapa de escaldagem. Dos quatro grupos de indicadores avaliados, nenhum apresentou correlação com a presença de Salmonella spp. e L. monocytogenes (p <0,05). Os resultados obtidos indicam a existência de etapas da cadeia de produção que se apresentam como críticas do ponto de vista sanitário, o que implica na necessidade de implementação de ações no processo para reduzir os níveis microbiológicos. / The pig slaughter process involve different steps that can influence the microbiological quality of carcasses. At this, the understanding of the slaughter process on the microbiological aspects is necessary for the implementation and evaluation of critical control points. The microbiological control of the slaughter process should involve the evaluation of pathogens prevalence and levels of quality and hygiene indicator microorganisms. This study aimed at investigating the influence of steps slaughter process on the microbiological levels of pig carcasses, and evaluate if there is correlation between pathogens (Salmonella spp. and Listeria monocytogenes) and indicators (aerobic mesophilic counts, total coliforms, Escherichia coli and Enterobacteriaceae) microorganisms. A high Salmonella soroprevalence in pigs were founded before the slaughter (57.49 %). While the Salmonella prevalence in carcasses at the initial stage of the slaughter was 26.67 % and in the final stage 1.11 %, L. monocytogenes was detected only in the final washing and cooling steps, with a prevalence of 21.11 and 8.89 %, respectively. The aerobic mesophilic counts, Enterobacteriaceae, total coliforms and E. coli levels in initial steps of slaughter process were 4.25 ± 0.37; 1.25 ± 0.38; 1.10 ± 0.35 and 0.86 ± 0.36, respectively. At the end of slaughter process the results were lower (ranging from 0.16 at 2.70 log CFU/cm2). The step that most reduced microbiological levels was the scalding. The dehairing was a critical step that led to a significant increase of microorganisms levels in the process (p < 0.05). The evisceration not proved to be a critical step on the increase of microbial levels, differently of the final washing, which showed significant increases (p < 0.05) over the levels of aerobic counts, total coliforms, E. coli and enterobacterias (0.30; 0.36; 0.27 and 0.42 log respectively) and Salmonella spp. and L. monocytogenes. The chilling contributes significantly to the reduction of microbiological levels of carcasses, bringing them to levels below the all process stages, with the exception of scalding. No correlation between the hygiene indicator microorganisms used and presence of Salmonella spp. and L. monocytogenes were obtained (p < 0.05). The results show that steps in the process are critical to the sanitary profile, which implies the need to implement actions in the process to reducing the microbiological levels.

<p>The United States is ranked third for global pork production as well as first in pork exports according to the USDA Economic Research Service in 2019. The majority of the commercial pork production in the United States applies some form of confinement system with environmentally adapted facilities. However, with information and easy media access to the US consumers, news and reports on different farming practices and potential issues in the animal industry have come under the spotlight. Consumers are becoming more interested in knowing what goes on behind the scenes of the commercial animal industry and where and how their food is produced. Whether it is due to personal beliefs, ethical concerns, novelty-seeking, eating experience, or choice of lifestyle, consumers are demanding diversity in their meat purchasing options. Although the commercial pork industry has shifted to fewer and larger farms in the last 40 years, small specialty farms such as heritage breed pork are on the rise to form a niche market. Large Black pig is a pasture-raised heritage breed originating in England, and it remains one of the rarest British pig breeds. Due to differences in husbandry, pasture-raised Large Black pigs consume a relatively high forage diet compared to corn-based diet used in commercial swine production. Although heritage pork has been lauded to have unique and superior quality, enhanced eating experience, and is often sold at a premium price, there are very little data on pork quality of Large Black pig compared to Duroc-sired breeds which are commonly used in commercial pork production. The purpose of this study is to fill the dearth and investigate differences in pork processing characteristics between commercial Duroc-sired and Large Black genetic lines fed high forage or commercial diets.</p><p> The study contained a total of 50 pigs: 25 Duroc-sired (DS) and 25 Large Black sired (LB) pigs. After all the pigs were weighed, the pigs were randomly assigned with heavy and light weights as blocks to two dietary treatments: Fiber (FIB) and Control (CON); and the feeding trial lasted a total of 126 days. There were 14 Large Black pigs fed fiber diet (LB FIB); 11 Large Black pigs fed control diet (LB CON); 14 Duroc-sired pigs fed fiber diet (DS FIB) and 11 Duroc-sired pigs fed control diet (DS CON). Pigs were fed either a control Corn-Soybean Meal-DDGS based diet or a high fiber diet with wheat middlings and dehydrated alfalfa meal replacing corn and soybean meal in the control diet. Diets were fed over six 21 days phases with fibrous ingredient levels increasing from 8.5 to 30 percent of the diet with sequential dietary phase from 1 to 6. Pigs were harvested at a common age with some variations in body weight between genetics (DS 125 ± 2.23 kg, LB 99 ± 2.28 kg; <i>P</i> < 0.001). Individual batches of 80% lean : 20% fat sausage patties with seasoning (136g per patty) were made from the shoulder of each pork carcass. PVC packaging was applied to each batch of sausage patties. Fat smear was noted on day 0 with a fat smear scale of 1 (excessive far smearing) to 8 (clear fat particle definition). Color parameters that include lightness (L*), redness (a*), yellowness (b*), and lipid oxidation (2-Thiobarbituric acid reactive substances, TBARS) due to retail display effect were measured at days 0, 3, and 7 by placing packaged sausage patties under the retail display lighting. Boneless bellies were removed and weighed (fresh weight) from each pig and measurements for belly thickness, length, and firmness were recorded. Fresh bellies were injected to 110% fresh weight, thermally processed (62°C), and cooled (1°C internal temperature). Cooked weight was obtained before slicing. Belly processing yield was calculated as a percentage using (cooked weight / fresh weight) x 100. Adobe Photoshop was used to perform visual image analysis for bacon slice length (SL; cm), slice area (SA; cm²), and slice lean area (LA; %), one 0.64 cm bacon slice was obtained from 25, 50, and 75% distance respectively from the blade end of each cooked bellies for the analysis. RStudio (1.2.1335) was used to analyze data with breed and diet as fixed effects and least square means separated at (<i>P</i> < 0.05).</p><p> Results showed that only diet was significant for patty fat smear (<i>P </i>= 0.0104), CON patties had better particle definition than FIB patties. Difference for patty color L* (<i>P </i>= 0.0051), a* (<i>P </i>< 0.0001) and b* (<i>P </i>< 0.0001) were found for days of retail display. Breed was significant in L* (<i>P </i>< 0.0001) and a* (<i>P </i>< 0.0001) with DS patties being lighter and less red than LB patties. Days under retail display (<i>P </i>< 0.0001) and breed x diet interaction (<i>P </i>= 0.0014) were found in lipid oxidation. DS CON had the least amount of lipid oxidation throughout retail display time. Breed and diet were significant for both belly thickness and length. LB (<i>P </i>= 0.0263) and CON (<i>P </i>< 0.0001) bellies were thicker than DS and FIB bellies respectively. DS (<i>P </i>< 0.0001) and CON (<i>P </i>= 0.0045) bellies were longer than LB and FIB bellies respectively. A breed x diet interaction (<i>P </i>= 0.0527) was observed in belly firmness and LB CON had the firmest bellies. Processing yield was found to be greater in DS bellies (<i>P </i>= 0.0014) than LB bellies. Breed effect had a tendency (<i>P </i>= 0.065) on SL, DS slices were longer. CON had greater SA (<i>P </i>< 0.0048) than FIB slices. DS slices had significantly higher LA (<i>P </i>< 0.0001) than LB slices.</p> The study provided novel insights into the differences in processing characteristics between the DS and LB genetic lines as well as the effect of diet on each breed. Results such as thicker and firmer belly, lower LA in LB were expected since LB is a minor swine breed that has not undergone intense genetic selection for percent lean meat. Overall, each breed had a better product when fed their accustomed diet (FIB for LB, CON for DS) such as less lipid oxidation in sausage patties for DS CON compared to LB CON. Although LB fits into the niche market of heritage breed pork, future studies in management systems, processing methods, and genetic improvement should be considered to improve product quality to better meet modern consumer demands.

<p>In recent years conservation of minor livestock breeds has been faced with numerous challenges attributed to decreasing national herd sizes, as well as differences in reproduction and growth. One such minor swine breed, the Large Black pig (LB), is increasingly attractive to small farmers due to their foraging abilities and carcass characteristics. Therefore, the LB pigs have been used in niche pork production systems which market pasture-raised pork products. The LB breed is critically endangered, maintaining a registered breeding population of less than 400 animals, with increasing prevalence of inbreeding and genetic drift. Therefore, the LB breed could benefit from a genetic importation to increase genetic diversity in a national herd with rapidly decreasing animal numbers. A genetic importation would require frozen semen to be brought in from another country for use in breeding U.S. pigs. Frozen-thawed semen (FTS) presents challenges for swine due to the reduced motile sperm cells which negatively impacts fertility. Therefore, the present study evaluated the utilization of FTS in a genetic importation for the LB pig. </p><p>A genetic importation occurred in 2016 where semen from the United Kingdom was used on various farms in the U.S. but resulted in zero piglets born. Therefore, 16 LB sows were donated to Purdue University for research into improving estrous and ovulation synchronization to facilitate FTS utilization. Four breeding replicates were performed where following 14 days of Matrix feeding, OvuGel® was administered at 144 h following last Matrix feeding (LMF) or 96 h in post-weaned sows and two FTS inseminations occurring at: 30 and 36 h, 17 and 23 h, 24 and 30 h, and 24 and 32 h after OvuGel® for replicates 1-4, respectively. Approximately 2.64±0.3 billion motile sperm cells per insemination were utilized in replicates 1-3 with American LB FTS, with replicate 4 utilizing 0.34±0.03 billion motile sperm cells of imported FTS. Follicle diameter (<i>P</i>=0.260), ovulation within 48 h of OvuGel® (<i>P</i>=0.411), and weight prior to breeding (<i>P</i>=0.681) did not influence conception rate, however expression of estrus was determined to significantly influence conception rate (<i>P</i>=0.043). Seventy-five LB piglets were weaned across the first three breeding replicates, with parity 2 sows observed to have larger litter sizes than parity 1 sows (<i>P</i>=0.066).</p> <p>Large Black and Duroc-sired (DS) crossbred pigs from replicates 1 and 2 farrowing were fed corn and soybean meal based finishing diets supplemented with (FIB) or without alfalfa and wheat middlings (CON). Following 6 dietary phases through finishing, 25 LB and 25 DS pigs were slaughtered at similar ages for digestive organ dissection and carcass measurements. Loin muscles were evaluated for fresh pork quality and instrumental color and tenderness. LB pigs had a reduced ADG (<i>P</i><0.0001) and G:F (<i>P</i><0.0001) compared to DS pigs. Pigs fed FIB resulted in reduced ADG (<i>P</i>=0.020) and reduced G:F (<i>P</i>=0.007). At slaughter LB pigs were 26.4 kg lighter than DS pigs (<i>P</i><0.0001), and pigs that were fed FIB had lighter live weights (<i>P</i>=0.002) than pigs fed CON. LB pigs had 28.5±1.3 cm² smaller longissimus muscle area (<i>P</i><0.0001), yielding 2.0 cm more 10^th rib back fat than DS pigs (<i>P</i><0.0001). CON pigs had heavier HCW (<i>P</i><0.0001) than FIB pigs, however FIB pigs had greater percent lean (<i>P</i>=0.015). LB pigs had significantly reduced percent lean than DS pigs (<i>P</i><0.0001). LB pigs had loins with reduced drip loss (<i>P</i>=0.009) and cooked shear force values (<i>P</i><0.0001). Overall, the growth and carcass composition of the pigs was most affected by genotype, and to a lesser extent than the type of diet fed. </p> <p>In conclusion, the genetic importation of LB semen was successful as ½ blood piglets were created for dispersal into the U.S. LB herd. Improvements in FTS utilization in this heritage breed contributed to the successful creation of live-born pigs. Additionally, growth and carcass information was obtained for LB breeders to use in understanding and marketing of this heritage breed of pigs.</p>

O objetivo desse trabalho foi avaliar a qualidade do produto final relacionado ao manejo pré-abate de suínos, que permitiu analisar os procedimentos e o cumprimento das normas de bem-estar animal. O manejo pré-abate é definido como o conjunto de práticas com os animais desde a propriedade até o frigorífico. Os procedimentos pré-abate estão diretamente relacionados a perdas relacionadas à qualidade da carne e perdas econômicas em todo o sistema produtivo. Foram avaliados 144 animais, em um período de seis dias de abate com relação à capacidade de retenção de água, pH inicial e final e coloração. Posteriormente, os resultados foram analisados com relação os defeitos tecnológicos como PSE e DFD. Conclui-se que o manejo inadequado influenciou na qualidade dos produtos. / The objective of this work was to evaluate the quality of the final product related to the pre-slaughtering of pigs, which allowed the analysis of procedures and compliance with animal welfare standards. Pre-slaughter management is defined as the set of practices with the animals from the property to the slaughterhouse. Pre- slaughter procedures are directly related to losses related to meat quality and economic losses throughout the production system. A total of 144 animals were evaluated over a six day slaughter period in relation to water retention capacity, initial and final pH, and staining. Subsequently, the results were analyzed with regard to technological defects such as PSE and DFD. It was concluded that improper handling influenced the quality of the products.

O objetivo desse trabalho foi avaliar a qualidade do produto final relacionado ao manejo pré-abate de suínos, que permitiu analisar os procedimentos e o cumprimento das normas de bem-estar animal. O manejo pré-abate é definido como o conjunto de práticas com os animais desde a propriedade até o frigorífico. Os procedimentos pré-abate estão diretamente relacionados a perdas relacionadas à qualidade da carne e perdas econômicas em todo o sistema produtivo. Foram avaliados 144 animais, em um período de seis dias de abate com relação à capacidade de retenção de água, pH inicial e final e coloração. Posteriormente, os resultados foram analisados com relação os defeitos tecnológicos como PSE e DFD. Conclui-se que o manejo inadequado influenciou na qualidade dos produtos. / The objective of this work was to evaluate the quality of the final product related to the pre-slaughtering of pigs, which allowed the analysis of procedures and compliance with animal welfare standards. Pre-slaughter management is defined as the set of practices with the animals from the property to the slaughterhouse. Pre- slaughter procedures are directly related to losses related to meat quality and economic losses throughout the production system. A total of 144 animals were evaluated over a six day slaughter period in relation to water retention capacity, initial and final pH, and staining. Subsequently, the results were analyzed with regard to technological defects such as PSE and DFD. It was concluded that improper handling influenced the quality of the products.

Made available in DSpace on 2015-03-26T13:55:27Z (GMT). No. of bitstreams: 1 texto completo.pdf: 443777 bytes, checksum: aa47df0593f4494e3ed6277403324b28 (MD5) Previous issue date: 2007-02-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this study was mapping QTL on pig chromosomes 16, 17 and 18 and associate them to performance, carcass, internal organs, viscera, carcass cuts and meat quality traits. A F2 population was produced by crossing two naturalized Brazilian Piau sires and 18 commercial dams (Landrace x Large White x Pietrain). The population was genotyped for 11 microsatellite markers. After the genotype scoring, it was constructed the linkage map for these markers in the population. The microsatellites markers were considered appropriate for quantitative trait analysis. It was analyzed their values for observed heterogosity (Ho), expected heterozigosity (He) and polymorphic information content (PIC). The evaluation of the four loci amplified in the SSC16 found average values of Ho, He; and PIC of 0,67, 0,57 and 0,50, respectively. In the SSC17 the average values for Ho, He and PIC of 0,72, 0,61 and 0,56, respectively for the four amplified loci. And in the SSC18, average values of Ho, He and PIC were 0,67, 0,63 and 0,59, respectively for each one of three loci. Data were analyzed by multiple regressions by F2 mapping method using the QTLEXPRESS software. Eleven QTL were mapped and not yet described in the literature: teat number, cooking loss, redness, lower backfat thickness after last lumbar vertebrae, bacon depth, heart weight and lung weight on SSC16. QTL for weight at 63 and 77 days of age were assigned on chromosome 17. QTL for weight at 21 days of age and slaughter age were identified on SSC18. Four QTL Already described in another populations were also identified: weight at 21 days of age on SSC16, backfat thickness after last lumbar vertebrae and after the last rib (at 6,5 cm from the midline ) on SSC17 backfat thickness after last lumbar vertebrae and after the last rib (at 6,5 cm from the midline) and total loss on SSC18. The generated information of significant QTL is useful for future studies dealing with fine mapping to identify genes that could provide a better understanding of the production traits in pigs. / O objetivo ao realizar este trabalho foi o mapeamento de QTL nos cromossomo 16,17 e 18 de suínos e a associação destes a característica de desempenho, de carcaça, órgãos internos e vísceras, de cortes de carcaça e de qualidade de carne. Foi construída uma população F2 provenientes do cruzamento de dois varrões da raça naturalizada Brasileira Piau com 18 fêmeas da linha comercial (Landrace x Large White x Pietrain). Foram utilizados onze marcadores microssatélites distribuídos nos SSC16, SSC17 e SSC18. Com o resultado da genotipagem foi construído o mapa de ligação específico dos marcadores para a população desenvolvida. Os marcadores de microssatélites foram considerados adequados para estudos de características quantitativas, quando foram analisadios os valores de heterozigosidade observada (Ho), heterozigosidade esperada (He) e conteúdo de informação polimórfica (PIC). A avaliação dos quatro locos amplificados no SSC16 forneceu valores das médias da Heterozigosidade observada (Ho) e esperada (He); e do Conteúdo de informação polimórfica (PIC) de 67,62%, de 57,71% e 0,50, respectivamente. No SSC17 foram encontrados os resultados das médias de Ho, He e PIC de 72,20%, 61,40% e 0,56, respectivamente para os 4 locos utilizados. E no SSC18, o valor das médias de Ho, He e de PIC foram 67,80% 63,54% e 0,59, respectivamente utilizando 3 locos. Foi utilizado o método de regressão por intervalo de mapeamento, e as análises foram realizadas por meio do programa QTLEXPRESS. Foram detectados 11 QTL não descritos na literatura: número de tetas, índice de vermelho; perda por cozimento, menor espessura de toucinho na região acima da última vértebra lombar na linha dorso-lombar, espessura de bacon, peso do coração e do pulmão no SSC16; peso aos 63 dias de idade e peso aos 77 dias de idade no SSC 17; peso aos 21 dias e idade de abate no SSC18; e quatro QTL já descritos em outras populações foram também identificados, como para peso aos 21 dias de idade no SSC16, espessura de toucinho medida imediatamente após a última costela, a 6,5 cm da linha dorso-lombar no SSC17, espessura de toucinho medida imediatamente após a última costela, a 6,5 cm da linha dorsolombar e perda total no SSC18. As informações dos QTL significativos encontrados servem como base de estudos futuros de mapeamento fino para identificação de genes permitindo o melhor entendimento das características de produção em suínos.

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.