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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.

This study assessed whether the meat tenderness of broilers raised in a free-range system varies by sex, lineage, and age at the time of slaughter. Physicochemical parameters were measured to adequately assess breast and thigh muscle morphometry, including shear force (SF), muscle fibre diameter (MD), histological connective tissue (HCT) content, and total and soluble collagen contents (TCC and SCC, respectively). The experiment was conducted with a completely randomized design using two lineages (Pescoço Pelado and Paraíso Pedrês), with specimens of both sexes raised in a free-range system. Randomly selected broilers were slaughtered at 65, 75, 85, and 95 days old. A total of 192 birds were analysed. SF values correlated positively with age. The highest SF values were measured in thighs of the Pescoço Pelado lineage. Age also showed a positive correlation with MD and HCT content of the breast regardless of lineage. Gender did not have any significant correlation with physical parameters; although, higher values were measured in thighs of the Paraíso Pedrês than in those of the Pescoço Pelado lineage. There were no significant differences among treatments regarding the SCC and TCC of thighs and breasts. Principal component analysis (PCA) revealed relationships between SF and the rest of the measured attributes. PCA showed that age was positively correlated with the SF, MD, and HCT content of thighs and breasts. In contrast, SCC and TCC had negative correlations. The greatest breast and thigh MD values were associated with the least tender meat. Thus, age at the time of slaughter proved to be the most significant parameter impacting the physical characteristics of muscle morphometry and meat tenderness of breasts and thighs of broilers raised in a free-range system. RESUMO: Objetivou-se com este estudo avaliar os fatores relacionados a maciez da carne de frangos criados em sistema alternativo. Para o experimento foi avaliado a força de cisalhamento, diâmetro das fibras musculares do peito e da coxa, conteúdo de tecido conjuntivo através de histologia e teor de colágeno solúvel e total. O experimento foi executado em delineamento inteiramente casualizado (DIC) com uso de duas linhagens (Pescoço Pelado e Paraíso Pedrês) de ambos os sexos (macho e fêmea) e abatidos em quatro idades (65, 75, 85 e 95 dias), criados em sistema alternativo, sendo utilizado um total de 192 aves. Para força de cisalhamento (FC), ocorreu aumento nos valores em ambos os cortes em função da idade de abate e houve interação entre linhagem e sexo, com as maiores médias para os machos da linhagem Pescoço Pelado e diferença entre sexo para Paraíso Pedrês. A idade de abate influenciou o diâmetro das fibras musculares e o conteúdo de tecido conjuntivo do peito e da coxa, havendo aumento linear destes parâmetros em função da idade ao abate. O sexo não afetou o diâmetro das fibras musculares da coxa, enquanto na linhagem Paraíso Pedrês foram verificadas maiores médias em relação à Pescoço Pelado. A análise de componentes principais demonstrou a relação entre a força de cisalhamento e as demais variáveis analisadas. Assim, o aumento do diâmetro das fibras musculares do peito e da coxa também está relacionado à redução da maciez da carne de frangos caipiras, conjuntamente com o aumento da quantidade de tecido conjuntivo, teor de colágeno total e redução de sua solubilidade.

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.