ABSTRACT The objective of this study was to evaluate the association of polymorphisms in the diacylglycerol acyltransferase ( DGAT ) and leptin ( LEP ) genes with the performance, carcass characteristics, meat quality, and lipid profile of Nellore cattle. A total of 100 intact male Nelore cattle were used to analyze the performance, carcass, physicochemical and centesimal composition, and fatty acid profile of beef. To identify the polymorphisms, the PCR–single-strand conformation polymorphism (SSCP) technique was applied to genomic DNA extracted from muscle tissue. The SSCP technique revealed the presence of four band patterns for the DGAT gene (AC, AD, AE and BB) with five alleles (A, B, C, D and E). For the LEP gene, five band patterns (AA, AB, AC, BB and BC) with three alleles (A, B and C) were observed. For the LEP gene, the AB genotype was associated with higher backfat thickness and ribs weight, while the BB genotype was associated with lower ribs yield; higher hindquarter yield was associated with AC and BB genotypes. Higher contents of C17:0, C18:0 and lower contents of C18:2ω6C, total polyunsaturated fatty acids, total ω6 and ratio of polyunsaturated and saturated fatty acids (PUFA/SFA) were verified for the AC genotype of the LEP gene. The AC and AA genotypes of the LEP gene were associated with higher means of C15:0 and C18:1ω9t. For the DGAT gene, the highest C24:0 content was associated with the AE genotype and the lowest with the AD and BB genotypes. Polymorphisms in the DGAT and LEP genes influence carcass parameters and the lipid profile of the meat of Nellore cattle.

RESUMO Objetivou-se com este estudo avaliar a associação do polimorfismo dos genes da Diacilglicerol Aciltransferase ( DGAT) e Leptina – (L EP ) em relação ao desempenho, características de carcaça, qualidade de carne e perfil lipídico de bovinos Nelore. Para o estudo, foram utilizados um total de 100 bovinos nelores machos inteiros e avaliado os parâmetros de desempenho, composição da carcaça, composição físico-química, centesimal e perfil lipídico da carne. Para identificação dos polimorfismos foi utilizada a técnica de PCR-SSCP a partir da extração do DNA genômico do tecido muscular. A técnica de SSCP revelou a presença de quatro padrões de banda para o gene DGAT (AC, AD, AE e BB) com cinco alelos (A, B, C, D e E) e, para o gene LEP foram verificados cinco padrões de bandas (AA, AB, AC, BB e BC) com três alelos (A, B e C). Para o gene LEP, o genótipo AB foi associado a maior espessura de gordura subcutânea e peso do corte ponta de agulha, enquanto o genótipo BB foi associado a menor rendimento do corte ponta de agulha; maior rendimento do corte traseiro foi associado aos genótipos AC e BB. Maiores teores de C17:0, C18:0 e menores de C18: 2ω6C, total de ácidos graxos poli-insaturados, total de ω6 e a relação de ácidos graxos poli-insaturados e saturados (POL/SAT) foram verificados para o genótipo AC do gene LEP. Os genótipos AC e AA do gene LEP foram associados a maiores médias de C15:0 e C18:1ω9t. Para o gene DGAT, os maiores teores de C24:0 foram associados o genótipo AE e o menores aos genótipos AD e BB. A ocorrência de polimorfismo nos genes DGAT e LEP revelaram influência destes sobre parâmetros de carcaça e perfil lipídico da carne de bovinos Nelore.

Abstract The objective of this work was to evaluate the replacement of choline chloride supplementation by herbal choline in the diet of nursery piglets. The experimental design was randomized complete blocks (initial weight and sex) with 80 piglets, in five treatments, with eight replicates. The treatments consisted of: negative control, basal diet supplemented with 300 mg kg-1 choline via choline chloride, basal diet supplemented with 600 mg kg-1 choline via choline chloride, basal diet supplemented with 100 mg kg-1 herbal choline, and basal diet supplemented with 200 mg kg-1 herbal choline. Zootechnical performance data, blood parameters, and economic viability were analyzed. Herbal choline supplementation increases the body weight and daily feed intake of nursery piglets. The supplementation with 100 mg kg-1 herbal choline presents the highest return on investment. Herbal choline can be used as a source of choline supplementation in the diet of nursery piglets to replace choline chloride.

Resumo O objetivo deste trabalho foi avaliar a substituição da suplementação de cloreto de colina por colina herbal na dieta de leitões na creche. O delineamento experimental foi em blocos ao acaso (peso inicial e sexo) com 80 leitões, em cinco tratamentos, com oito repetições. Os tratamentos consistiram em: controle negativo, dieta basal com suplementação de 300 mg kg-1 de colina via cloreto de colina, dieta basal com suplementação de 600 mg kg-1 de colina via cloreto de colina, dieta basal com suplementação de 100 mg kg-1 de colina herbal e dieta basal com suplementação de 200 mg kg-1 de colina herbal. Dados de desempenho zootécnico, parâmetros sanguíneos e viabilidade econômica foram analisados. A suplementação de colina herbal aumenta o peso corporal e o consumo diário de ração em leitões na creche. A suplementação com 100 mg kg-1 de colina herbal apresenta o maior retorno sobre o investimento. A colina herbal pode ser utilizada como fonte de suplementação de colina na dieta de leitões na creche, para substituir o cloreto de colina.

Abstract The objective of this work was to determine the fatty acid profile of artisanal Minas cheese from seven certified regions in the state of Minas Gerais, Brazil. A total of 78 samples were collected in regions where the producers were registered by Instituto Mineiro de Agropecuária. For lipid profile determination, different cheese varieties from the following regions were analyzed: Canastra, Serro, Araxá, Serra do Salitre, Triângulo Mineiro, Campo das Vertentes, and Cerrado. The lipid profile of Serra do Salitre and Araxá cheeses was similar in caproic acid (C6:0), total polyunsaturated fatty acids, and ratio of polyunsaturated and saturated fatty acids. In the other regions, lipid profile differed due to associations with specific fatty acids, such as those of the cheeses from Triângulo Mineiro with C20:5n3, of Cerrado with C20:4n6, of Canastra with C8:0, of Serro with C22:2 and C22:6n3, and of Campo das Vertentes with C17:0, C18:0, and C20:0. The fatty acid profile and nutritional indices related to the lipid profile of artisanal Minas cheeses differ according to the region of origin. The content and profile of omega 3 fatty acids are significant parameters to differentiate artisanal Minas cheeses. Serro artisanal Minas cheese presents superior nutritional indices concerning fatty acid profile than the other studied cheeses.

Resumo O objetivo deste trabalho foi determinar o perfil de ácidos graxos em queijos minas artesanais provenientes de sete regiões certificadas no estado de Minas Gerais, Brasil. Um total de 78 amostras foram coletadas em regiões com produtores cadastrados pelo Instituto Mineiro de Agropecuária. Para determinar a composição lipídica, foram analisadas diferentes variedades de queijo das seguintes regiões: Canastra, Serro, Araxá, Serra do Salitre, Triângulo Mineiro, Campo das Vertentes e Cerrado. A composição lipídica dos queijos da Serra do Salitre e de Araxá foi similar em ácido caproico (C6:0), total de ácidos graxos poli-insaturados e razão entre ácidos poli-insaturados e saturados. Nas outras regiões, a composição lipídica diferiu devido a associações com ácidos graxos específicos, como as dos queijos das regiões do Triangulo Mineiro com C20:5n3, do Cerrado com C20:4n6, da Serra da Canastra com C8:0, do Serro com C22:2 e C22:6n3 e de Campo das Vertentes com C17:0, C18:0 e C20:0. O perfil de ácidos graxos e os índices nutricionais relacionados ao perfil lipídico dos queijos minas artesanais diferem de acordo com a região de origem. O teor e o perfil de ácidos graxos ômega 3 são parâmetros importantes para diferenciar os queijos minas artesanais. O queijo minas artesanal do Serro apresenta melhores índices nutricionais quanto ao perfil de ácidos graxos que os demais queijos estudados.

Abstract An experiment was conducted to evaluate the effects of increasing concentrations of crude glycerin, with or without ractopamine, in the diet of finishing barrows on carcass characteristics and pork quality. The experimental design was a randomized complete block, in a 4 x 2 factorial scheme, with four concentrations of crude glycerin (0, 100, 150, or 200 g/kg) and two concentrations of ractopamine (0 or 10 mg/kg). There was no interaction between the crude glycerin concentrations and the ractopamine use as well as there was no isolated effect of the dietary crude glycerin concentration for all the evaluated traits. However, the dietary ractopamine increased the hot (p = 0.021) and cold (p=0.020) carcass weight, the hot carcass yield (p = 0.038), the shear force (p = < 0.0001), lightness (L* index) (p = 0.043), hue angle (h*) (p = 0.026), and C16:1 (p = 0.023) concentration in the loin. Moreover, the dietary ractopamine decreased the red content (a* value) (p = 0.043), the activity of C16-C18 elongase (p = 0.037) and the C18:0 (p = 0.021) concentration in the loin. The inclusion of up to 200 g/kg crude glycerin in the diet of finishing pigs may be used as a partial substitute for dietary corn, combined or not with 10 mg/kg ractopamine, without impair the evaluated carcass characteristics and the quality of the loin.

Abstract This research study aimed to evaluate the influence of sexual maturity on meat quality parameters in chickens raised in a free-range system. The fully randomized design (FRD) used a (2x2) factorial scheme, with two sexes (male and female) and two categories of sexual maturity (immature and mature). Ninety birds (45 females and 45 males) belonging to the Label Rouge (Pescoço Pelado) strain were slaughtered at five different ages (70, 90, 120, 150, and 180 days). The physicochemical parameters, centesimal composition and shelf life of the meat were assessed. In both breast and leg cuts, sexual maturity promoted an increase in shear force and affected the meat color by increasing its redness (a*). Moisture was higher in leg meat after sexual maturity. In both breast and leg cuts, ether extract was higher in sexually mature females. Sexual maturity also caused a decrease in tenderness and shorter shelf life of the meat.

ABSTRACT This study aimed to evaluate the effects of zinc oxide and a low level of encapsulated zinc oxide, with or without dietary fiber, on the performance and intestinal health of weaned piglets. A total of 112 piglets were used, divided into four treatment groups: basal diet with zinc oxide (ZnO); basal diet with zinc oxide and dietary fiber (ZnO+DF); basal diet with encapsulated low zinc oxide (LZnOE); and basal diet with LZnOE and DF (LZnOE+DF). Piglets were challenged with E . coli K88 + , weighed weekly and the fecal score was evaluated daily. One pig per pen was slaughtered to evaluate the production of volatile fatty acids, intestinal microbial populations, intestinal morphology, and digestibility. The encapsulated zinc resulted in lower body weight and average daily gain, but, when associated with dietary fiber, had similar results to zinc oxide. Until 49 days of age, zinc oxide reduced diarrhoea ( p < 0.05). At 63 days of age the piglets subjected to LZnOE+DF treatment had lower diarrhoea than the pigs subjected to LZnOE treatment but higher than the ZnO and the ZnO+DF groups. Final weight and incidence of diarrhoea of pigs receiving LZnOE was worse than ZnO. LZnOE associated with DF provided the same final weight of piglets from the ZnO group.

RESUMO O objetivo com o trabalho foi avaliar a viabilidade econômica da suplementação de L-arginina em dietas para matrizes suínas durante a fase de lactação. Um estudo de caso descritivo foi realizado para identificar a viabilidade econômica da suplementação de L-arginina na ração de lactação, em relação à dieta controle, sobre o desempenho produtivo de matrizes suínas hiperprolíficas e suas leitegadas. O estudo foi realizado em uma granja comercial localizada no estado de Minas Gerais. Analisou critérios de viabilidade como o produto físico marginal (MPPg) e margem bruta (GM) no cenário de eficiência técnica e econômica, que foram comparados com o GM no grupo controle. A eficiência técnica foi estabelecida em 0,71% de L-arginina no consumo diário de ração de acordo com trabalho de campo prévio realizado pelos autores, enquanto a eficiência econômica obtida neste estudo foi de 0,43% de suplementação. A relação entre o preço da L-arginina e o preço de venda dos leitões determinou diretamente a viabilidade econômica, comparado ao grupo controle. Assim, considerando inicialmente o preço de um leitão como R$ 9,76/kg, o custo da L-arginina não deve exceder 6,61 vezes esse valor; isto é, estima-se em até R$ 64,50. Portanto, ao preço final de L-arginina de R$ 54,88, um leitão deve ser vendido ao preço de R$ 8,30/kg para tornar a suplementação de L-arginina na dieta de matrizes suínas em fase de lactação economicamente viáveis.

ABSTRACT The objective of this study was to evaluate the economic viability of L-arginine supplementation in diets for sows during the lactation phase. A descriptive case study was carried out to identify the economic viability of the supplementation of L-arginine in the lactation ration, in relation to the control diet, on the productive performance of hyper prolific sows and their litters. The study was carried out on a commercial farm located in the state of Minas Gerais. It analyzed feasibility criteria such as the marginal physical product (MPPg) and gross margin (GM) in the scenario of technical and economic efficiency, which were compared to the GM in the control group. Technical efficiency was established at 0.71% of L-arginine in daily feed intake according to previous fieldwork by the authors, while economic efficiency obtained in this study was 0.43% supplementation. The relationship between the L-arginine price and the sale price of the piglets directly determined the economic viability, compared to the control group. Thus, initially considering the price of a piglet as R$ 9.76/kg, the cost of L-arginine should not exceed 6.61 times this value; that is, it is estimated at up to R$ 64.50. Therefore, at the final price of L-arginine of R$ 54.88, a piglet should be sold at a price of R$ 8.30/kg to make the supplementation of L-arginine in the diet of lactation-phase swine economically possible.

ABSTRACT The intestinal gene expression of RelA/p65 (NF-κB), insulin growth factor 1 (IGF-1), glucose transporter 2 (GLUT2), and Na+/dependent glucose transporter 1 (SGLT1) were evaluated in response to benzoic acid, yeast culture, L-glutamine, and oregano essential oil, using an ex vivo model. Six piglets weighing approximately 20 kg each were sacrificed, and their jejunum was collected and segmented into five 2-cm explants. Each explant was immersed in cell culture medium according to one of the following treatments: control (without additive), 0.5% benzoic acid, 1% yeast culture, 1% L-glutamine, and 0.015% oregano oil. Gene expression was evaluated using RT-PCR. Yeast culture up-regulated the gene expression of RelA/p65, IGF-1, GLUT2, and SGLT1 in comparison with control. In addition, jejunal exposure to L-glutamine and oregano oil increased mRNA levels of GLUT2 compared with the control treatment. Exposure to oregano oil increased intestinal SGLT1 gene expression, while benzoic acid reduced SGLT1 expression compared with the control. Feed additives can differently modulate the gene expression of immune response, gut development, and glucose absorption in jejunal explants. These findings can contribute for a better understanding of the trophic action of these feed additives into the diets to optimize animal performance.

ABSTRACT The objective of this study was to evaluate the effect of L-arginine supplementation in lactation diets on the productive and reproductive performance of pluriparous sows and their litters. Seventy-six sows of the same genetic line were assigned to four treatments in a completely randomized design with 19 replicates. The experimental unit was the sow and its respective litter. Treatments comprised a control diet (no L-arginine supplementation) and other three diets obtained by top dressing the control diet with 0.5, 1.0, and 1.5% of L-arginine. L-arginine supplementation had no effect on any performance variables, body condition, milk production, or weaning-estrus interval. There was a quadratic effect on percentage of protein and fat in milk as well as on the daily production of these components. Protein and fat percentage declined during lactation. Adding L-arginine to the diet had a quadratic effect on piglet weight at 13 and 21 days, the optimal level of L-arginine supplementation being estimated as 0.64% and 0.71%, respectively. L-arginine supplementation had a quadratic effect on the weight gain of piglets during the first 13 days and on total period of lactation, the optimal level of L-arginine supplementation being estimated as 0.60% and 0.70%, respectively. Supplementing lactation diets with 0.70% of L-arginine, corresponding to 45 g day−1, improves the weight gain of piglets by improving the nutritional quality of sow milk.

RESUMO O objetivo com este estudo foi avaliar as características de desempenho, carcaça, qualidade de carne, perfil de ácidos graxos e alterações hepáticas de bovinos suplementados com caroço de algodão (CA) em terminação. Utilizou-se 100 animais da raça Nelore, sendo divido em dois grupos de 50 animais, sendo para o grupo 1 foi incluído CA na forma de grão inteiro na dieta (15% de inclusão) e para o grupo 2, foi fornecido uma dieta controle. Os animais permaneceram em confinamento durante 88 dias e as dietas fornecidas foram isoproteícas e isoenergéticas, na proporção de Concentrado: Volumoso de 60:40. Ao final do período experimental, os animais foram encaminhados para abate sendo coletadas amostras de fígado para análise histológica. Após resfriamento de 24 horas a ± 1°C, foram realizadas avaliações de carcaça e de cortes principais, pH e coleta de amostras do músculo Longissimus para realização das análises físico- química, de composição centesimal, perfil de ácidos graxos e índice de oxidação. A inclusão do CA na dieta proporcionou animais com maior peso ao abate, ganho de peso diário, rendimento de dianteiro. Porém, os animais apresentaram reduzidos rendimentos de carcaça, peso de traseiro e costelas, sem alterar os parâmetros como área de olho de lombo e cobertura de gordura subcutânea. Houve aumento dos valores de amarelo (b*) e umidade, com redução de pH final com uso do CA. Não houve influência do uso de CA em relação aos parâmetros histológicos avaliados no fígado. A inclusão de 15% de CA promoveu melhoria no desempenho dos bovinos em confinamento, com redução do peso do traseiro e adequados aspectos de qualidade de carne, perfil de ácidos graxos e conservação.

SUMMARY The objective of this study was to evaluate the performance, carcass, meat quality, fatty acid profile and liver alterations of cattle supplemented with cottonseed feedlot. It used 100 Nelore cattle, being divided into two groups of 50 animals, which received a cottonseed (CS) in grain form by the diet in the proportion of 15% and the other group was provided with control diet without CS in the feedlot for 88 days. The diets were isoprotein and isoenergetic and concentrate:roughage ratio of 60:40. The animals were slaughter in the end of experimental time and the collection of liver samples for histological analysis. After cooling 24 hours at ± 1°C were conducted evaluation of carcass and major cuts, final pH and collected muscle samples longissimus to carry out the physicochemical analyzes (Color, Cooking Loss, Pigments and Shear Force), chemical composition, fatty acid profile and oxidation. The inclusion of CS in the diet provided animals with higher slaughter weight, daily weight gain, Hindquarter, however, the animals showed reduced carcass yield, forequarter weight and Thin flank, without changing the parameters as rib-eye area and backfat thickness. There was an increase of the yellow values (b*) and moisture with the final pH reduction. There was no influence of the use of cottonseed in relation to histological parameters evaluated in the liver. The cottonseed in the feeding feedlot cattle promoted improvement in animal performance, despite the reduction of the forequarter weight, with appropriate aspects of meat quality, fatty acid profile and conservation.

RESUMO: O objetivo deste estudo foi avaliar os efeitos da adição do óleo essencial de aroeira ( Schinus terebinthifolius Raddi) na dieta de suínos sobre as características físicas, composição química e oxidação lipídica da carne. Setenta e dois leitões recém-desmamados (5,7±0,8kg) foram utilizados em um experimento em blocos completos casualizados com quatro tratamentos, seis repetições por tratamento e três animais por unidade experimental (baia). Os animais foram alimentados com uma dieta basal suplementada com 0, 500, 1,000 ou 1,500mg kg-1 de óleo essencial de aroeira durante 35 dias. Ao final do experimento, um animal por unidade experimental (16,4±2,2kg) foi abatido para coleta do músculo Longissimus dorsi para fim de análises. Não houve efeito (P>0,05) do óleo essencial de aroeira sobre cor, pH, perda de peso por cozimento e força de cisalhamento. A inclusão de níveis crescentes do óleo essencial de aroeira na dieta aumentou linearmente (P<0,05) o conteúdo de ácidos graxos saturados do músculo dos suínos, principalmente, as concentrações de mirístico (C14:0) e esteárico (C18:0). Para as análises de TBARS, a inclusão de óleo essencial de aroeira reduziu, significativamente, a produção de compostos secundários da oxidação lipídica nas amostras de carne crua (P<0,001) e imediatamente após o cozimento (P<0,001). Entretanto, durante oito dias de armazenamento refrigerado, a adição do óleo essencial de aroeira não protegeu eficientemente (P>0,05) os lipídios da oxidação. Portanto, o óleo essencial de aroeira, adicionado às dietas para suínos, aumentou o conteúdo de ácidos graxos saturados e reduziu a oxidação lipídica na carne fresca e logo após cozimento, sem ocorrer efeitos sobre os parâmetros físicos da carne.

ABSTRACT: The purpose of this study was to evaluate the effects of feeding pigs with diets containing increasing levels of Brazilian red pepper essential oil ( Schinus terebinthifolius Raddi) on the physical attributes, fatty acid profile and oxidative stability of precooked meat. Seventy-two weanling pigs (5.7±0.8kg) were allotted in a completely randomized block design experiment with four treatments, six replicates per treatment, and three animals per experimental unit (pen). Animals were fed with a basal diet supplemented with 0, 500, 1,000, or 1,500mg kg-1 Brazilian red pepper essential oil during the 35-d experimental period. At the end of the experiment, one animal per experimental unit (16.4±2.2kg) was slaughtered to sample Longissimus dorsi muscle for analysis. Dietary supplementation of Brazilian red pepper had no effect (P>0.05) on pork meat color, pH, cooking loss and shear force. Inclusion of essential oil in the diet provided a linear increase (P<0.05) of the saturated fatty acids content of L. dorsi, especially myristic (C14:0) and stearic (C18:0) fatty acids. Utilization of essential oil in pig diets reduced significantly the production of secondary lipid oxidation compounds measured as TBARS in raw pork meat (P<0.001) and immediately after cooking (P<0.001). However, during 8-d storage assay, the addition of essential oil in the diet did not protect pork meat lipids from oxidation. Therefore, Brazilian red pepper added to pig diets increased the saturated fatty acids content and reduced lipid oxidation in fresh meat and short-term heat treatment without affecting pork meat physical attributes.

Foi conduzido um experimento para avaliar a adição de butirato de sódio, extratos vegetais e nucleotídeos sobre desempenho, pH do conteúdo digestório, morfometria dos órgãos e histologia do epitélio intestinal de leitões desmamados. Foram utilizados 90 leitões, com idade média de 21 dias e peso médio inicial de 6,35±0,34kg. Os leitões foram distribuídos em um delineamento em blocos casualizados completos, com cinco tratamentos, seis repetições por tratamento e três animais por unidade experimental. As dietas experimentais consistiam de: Controle - dieta basal sem antibiótico; Antibiótico - dieta basal com 40mg kg-1 de sulfato de colistina; Aditivo: 1000, 1500 e 2000mg kg-1 de uma combinação de butirato de sódio + extrato vegetal + nucleotídeos. No 35o dia de experimentação, foi eutanasiado um animal por gaiola (unidade experimental) para avaliar o pH do conteúdo digestório, morfometria de órgãos e histologia do epitélio intestinal. Não foram observadas diferenças (P>0,05) para desempenho, pH do conteúdo digestório, morfometria de órgãos e histologia do epitélio intestinal por meio das análises de polinômios ortogonais ou mesmo pelos contrastes. A combinação de butirato de sódio, extratos vegetais e nucleotídeos não melhorou as características produtivas de leitões desmamados.

An experiment was conducted to evaluate the addition of sodium butyrate, plant extracts and nucleotides on weanling pig performance, digestive content pH, organ morphometry, and intestinal epithelial histology. A total of 90 piglets at 21 days of age and an average initial weight of 6.35±0.34kg were used. The piglets were distributed in a randomized complete block design with five treatments, six replicates, and three animals per experimental unit. The treatments consisted of the following: Control: basal diet without antibiotic; Antibiotic: basal diet with 40mg kg-1 colistin sulfate and Additive: 1000, 1500 and 2000mg kg-1 of a combination of sodium butyrate + plant extracts + nucleotides. The experiment lasted 35 days, at which time one animal was slaughtered to assess pH of the digestive contents, morphometry of the organs and histology of the intestinal epithelium. No differences were found (P>0.05) in the performance, pH of the digestive contents, morphometry of the organs or histology of the intestinal epithelium by the analysis of orthogonal polynomials or contrasts. The combination of sodium butyrate, plant extracts and nucleotides not improved the productive characteristics of weanling pigs.

This study evaluated the effect of ractopamine (RAC) on the performance of finishing pigs and the meat quality of these animals. Seventy crossbred pigs (35 barrows and 35 females) selected for high gain of lean meat, with initial weight of 77.1±0.32 kg were distributed in randomized blocks with five treatments (0, 5, 10, 15, and 20 ppm RAC in the diet) and seven replications during 28 days. The experimental unit was represented by a male and a female pig. Regarding the performance variables, there was a linear increase in final weight with increasing levels of RAC, as well as in average daily weight gain. An improvement in feed conversion was observed for animals fed RAC, and the optimal level - estimated by the LRP model - was ~ 5 ppm. For feed intake, no significant effect on intake of digestible lysine and energy intake was observed. Carcass yield responses increased linearly with the RAC dose. Ash content, color component b* and loss drip linearly decreased with increasing doses of RAC. There was also a significant difference in the percentage of ether extract and crude protein in the loin, and treatment with 20 ppm RAC showed a lower amount of protein and larger amounts of lipids. Moisture content, color component L*, weight loss by cooking and defrosting, shear force and pH were not affected by the treatment. Concerning the lipid oxidation, there was no effect of RAC on the concentration of TBARS (thiobarbituric acid reactive substances) under cooling and under freezing. Thus, all ractopamine levels improve performance compared with control and do not negatively affect the quality of fresh, chilled or frozen pig meat.

The aim of this article was to evaluate the in vivo mechanism of action through which ractopamine reduces the amount of adipose tissue in carcass of animals fed diets supplemented with this drug. Literature search was carried out, using the keywords Ractopamine, lipogenesis, lipolysis, fatty acid and adipose tissue. The scoring system was designed for the adequacy of the methodology. A total of eight papers were found - all published in the English language. The determination of lipolysis and lipogenesis was carried out using different methods - from the quantification of non-esterified fatty acids in the blood to molecular analyses of adipose tissue. The review analysis suggested that, at least in the pigs, the use of this drug reduced lipid deposition in the carcass due to a greater inhibition of lipogenesis than an increase in lipolysis.

Performance and carcass and cut yield of finishing pigs of three sexual categories fed diets with different levels of ractopamine were studied. Forty-eight hybrid animals (initial weight of 92.1±2.4 kg) were distributed in a completely randomised design in 3 × 2 factorial arrangement (three sexual categories: surgically castrated males, two females and immunologically castrated males - with or without 10 ppm of ractopamine), totalling six treatments and eight repetitions with one animal per experimental plot during 28 days. Ractopamine improved weight gain and feed conversion of all sexual categories. The best results were obtained with immunologically castrated males, which, in turn, had lower carcass yield and backfat thickness in the belly. In the absence of ractopamine, depth and loin eye area were higher in females but no differences in these variables were observed between categories when this additive was used. Ractopamine increased the sirloin yield in all sexual categories. There was no difference in bonus index. Ractopamine improves the performance of pigs of 92 to 125 kg. Immunologically castrated males have the best performance responses to ractopamine, but with losses in carcass yield, loin characteristics and backfat thickness of the belly.