Fat Deposition, Fatty Acid Composition, and Its Relationship with Meat Quality and Human Health

The consumer’s profile has changed, and in recent years, there has been a greater concern for the nutritional quality of meat, especially in relation to fat that compose it. The meat fat composition can contribute to the onset of cardiovascular disease. On the other hand, fat is an essential component in the human diet, as well as providing energy; it contains essential fatty acids (FAs) that must be present in food. The meat nutritional properties are largely related to its fat content and fatty acid composition. In addition, fat gives flavor to food, helps in the absorption of vitamins, and plays an important role in the immune response, for humans, and animals. The fat nutritional and sensory quality in meat that is determined by the fatty acid composition can affect the degree of fat saturation, the storage stability, and flavor. There are several factors that can influence the fatty acid composition, such as animals’ species, breed, sex, and diet, causing various changes in carcass, as well as in tissues and chemical meat composition

Sexual condition effects on performance, carcass traits and beef quality of feedlot crossbred Angus x Nellore cattle

Objetivou-se avaliar a influência da condição sexual sobre o desempenho, características de carcaça e qualidade da carne de bovinos Angus x Nelore, terminados em confinamento. Foram utilizados 176 bovinos, com idade média de 20 meses, pertencentes ao Programa Brasileiro de Carne Angus Certificada, divididos em quatro condições sexuais (CS): 32 machos não castrados (NC), 48 machos castrados cirurgicamente (CC), 48 machos imunocastrados (IM) e 48 fêmeas (F). Para a imunocastração dos bovinos, foram utilizadas três doses de uma vacina anti-GnRH. Os animais foram confinados durante 190 dias, com a mesma dieta, composta de 80% de concentrado e 20% de volumoso na matéria seca. Ao final deste período, os bovinos foram abatidos. Durante o abate, foi calculado o rendimento de carcaça quente (RCQ) e avaliado o pH. Na desossa, foi avaliada no m. Longissimus a área de olho de lombo (AOL), espessura de gordura subcutânea (EGS) entre a 12ª e 13ª costelas, marmorização, cor e pH. Foram coletadas amostras de 2,54 cm de espessura do m. Longissimus, embaladas a vácuo e maturadas por zero (sem maturação), 7 e 14 dias, a 2°C para análises de maciez objetiva (FC) e subjetiva, perdas por cocção (PPC), teor de extrato etéreo (EE) e perfil de ácidos graxos. Utilizou-se o procedimento MIXED do programa SAS® e a significância foi declarada quando P ≤ 0,05. Os machos NC apresentaram maior peso vivo final, ganho de peso médio diário, AOL e maiores valores de pH em relação às demais condições sexuais (P < 0,01). Para PCQ, os machos NC e IM apresentaram valores mais elevados do que machos CC e fêmeas (P < 0,01). Por outro lado, as fêmeas apresentaram maior EGS em relação às demais categorias (P < 0,01). O escore de marmorização foi maior na carne das fêmeas e machos CC do que dos machos NC e IM (P < 0,01), no entanto, a carne dos machos CC apresentou maior escore de gordura intramuscular Prime do que a carne das fêmeas. Para RCQ não houve diferença entre as CS. Houve maior PPC na carne dos machos CC (P < 0,01) e a carne das fêmeas apresentou maior teor de EE em relação às demais categorias (P = 0,0248). Houve interação entre CS e dias de maturação para os valores de FC (P = 0,0002) e para os valores de L* (P = 0,0118) e b* (P = 0,0113). A maturação influenciou a cor da carne, em função da CS e ambas favoreceram a maciez da carne de todas as CS avaliadas, especialmente de machos NC e fêmeas. A CS influenciou todos os atributos avaliados na análise sensorial (P < 0,05). A carne de fêmeas e animais castrados, sejam imunocastrados ou castrados por método cirúrgico, apresentaram melhor aceitação pelos consumidores na análise. Adicionalmente, a carne das fêmeas apresentou PAG mais favorável à saúde humana, enquanto a carne dos machos NC apresentou um perfil de AG menos saudável (P < 0,05). A imunocastração pode ser uma alternativa à castração cirúrgica, pois os resultados associados à melhoria na qualidade da carne de bovinos cruzados Angus x Nelore, são similares aos encontrados para os machos CC. Entretanto, vale ressaltar que os bovinos CC produzem carne com maior deposição de gordura intramuscular do que os IM e que os custos financeiros da imunocastração devem ser levados em consideração para a produção da carne. Ainda, as diferenças no perfil de ácidos graxos podem indicar que a CS pode impactar o valor nutricional da carne em termos de saúde humana.The goal of this work was to evaluate sexual condition effects on performance, carcass traits, and meat quality of a feedlot Angus x Nellore cattle. Were used 176 cattle, 20 months of age, from the Brazilian Certified Angus Beef Program, assigned into four sexual conditions: 32 bulls, 48 steers, 48 immunocastrated, and 48 heifers. The immunocastrated were obtained by vaccinating three times with anti-GnRH vaccine. Animals were fed ad libitum with a highgrain diet containing 80% concentrate. At the end of the experimental period (190 days) the animals were harvested. At the slaughter were collected data related to the carcass yield and pH values. After slaughter, were evaluated in Longissimus muscle, the rib eye area, and subcutaneous fat thickness between the 12th and 13th ribs, marbling score, color, and pH. Vacuum packaged steaks (2.54 cm thick) from the Longissimus muscle were collected, aging for zero, 7, and 14 days at 2°C and stored at -18°C until analysis of meat quality. Statistical analyzes were performed using the proc MIXED SAS® program (version 9.2). Bulls presented increased final body weight, average daily gain, rib eye area, and pH values when compared with the other sexual conditions (P < 0.01). For hot carcass weight, bulls and immunocastrated had higher values compared to steers and heifers (P < 0.01). Interestingly, heifers presented higher subcutaneous fat thickness compared to the other categories (P < 0.01). Heifers and steers presented increased intramuscular fat scores compared to the bulls and immunocastrated; however, beef from steers presented higher marbling Prime scores when compared with beef from heifers. Beef from steers had higher cooking loss (P < 0.01) and beef from heifers presented higher ether extract content when compared with other sexual conditions (P = 0.0248). There was interaction between sexual condition and aging time for Warner Bratzler Shear Force (WBSF) values (P = 0.0002), L* (P = 0.0118) and b* (P = 0.0113) values. The period of aging affected beef color, depending of the sexual condition. In addition, all cattle categories evaluated had beef tenderness improved by the aging process and sexual condition, especially beef from bulls and heifers. Sexual condition had main influence in all beef sensorial attributes (P < 0.05). Beef from heifers, steers, and immunocastrated cattle had better consumer´s acceptability in sensory analysis then the beef from bulls. Additionally, beef from heifers presented favorable fatty acid profile for human healthy, while beef from bulls had an unfavorable fatty acid profile (P < 0.05). In conclusion, immunocastration can be an alternative to surgical castration, since it improves meat quality with results like those for Angus x Nellore steers. However, it is important to highlight that the steers produce high intramuscular fat deposition then the immunocastrated, and the cost of immunocastration should be taken into consideration for the beef cattle production. Additionally, the difference on fatty acid profile can indicate that the sexual condition can impact the nutrition values of the meat

Análise da expressão de genes associados à adipogênese e composição da gordura intramuscular em bovinos Angus X Nelore de diferentes condições sexuais

Cattle growth, muscle adipose tissue and fatty acid composition in different muscles, are significantly affected by gender and influenced by a variety of hormonal factors, affecting the quality of the carcass and the beef. As the adipogenesis is a complex biological process to regulate fat cell metabolism, it can be regulated by hormones and influenced by factors such as different fat deposits, the gender status and diet of cattle. Therefore, it is important to understand the molecular mechanisms involved in adipogenesis in different muscles and gender, since the deposition of fat in these animals is different, to employ new tools to add greater value to meat production. However, the present study evaluated the association of fatty acid (FA) composition and adipogenesis-related genes in the longissimus (LO) and triceps brachii (TB) muscles of feedlot Angus x Nelore cattle. A total of 150 cattle was confined for 150 days and assigned to three genders, namely, heifers, bulls, and steers, and fed the same diet. Immediately after slaughter, samples of LO and TB muscles were collected for RNA and protein extraction. Twenty-four hours after slaughter, were measured the fat thickness and marbling score between the 12th and 13th ribs and collected samples of the muscles for analyses of total lipids determination and fatty acid composition. The experimental design was completely randomized, with 50 repetitions per treatment, and each animal was considered an experimental unit. The statistical analyses were performed by the proc MIXED SAS® (version 9.3) for the meat quality traits and JMP14 Software (SAS Institute) for the gene expression analyses. There was difference in the carcass traits related to fat deposition (P ≤ 0.05). The fat thickness and marbling score were higher in heifer carcasses than in carcasses of bulls and steers. Similarly, only gender status affected the content of total lipids (P ≤ 0.05), where meat from heifers presented increased values compared to steers and bulls. There was a difference in the total saturated FAs (SFAs) by gender and muscle type (P ≤ 0.05). The meat from bulls had higher levels of SFAs compared to heifers and had no differences in relation to meat from steers. Among muscle types, total SFAs increased in LO muscle compared with TB, independent of gender. The FAs 14:0 and 16:0 were affected by muscle type only, and higher levels were detected in the LO muscle (P ≤ 0.05). There were differences in gender for total monounsaturated FAs (MUFAs; P ≤ 0.05). Meat from bulls had lower levels of MUFAs compared with the other genders. The levels of the major FA of total MUFAs, 18:1 n-9c, were higher in the LO muscle than in the TB muscle, independent of gender (P ≤ 0.05). The total polyunsaturated FAs (PUFAs), total n-3, total n-6, PUFA:SFA ratio, health index and FAs 18:2 n-6c, 20:3 n-3, and 22:4 n-6 were higher in TB than in LO muscle (P < 0.05). Otherwise, the atherogenicity and thrombogenicity indexes were higher in the LO muscle (P ≤ 0.05). Regarding the transcript levels, there was an effect of muscle type on the expression of the CEBPa and LPL (P ≤ 0.05) genes, both of which had higher expression in TB muscle. Gender affected the transcript level of ACC (P ≤ 0.05). This gene was increased in bulls, intermediate in steers, and decreased in heifers. Additionally, gender and muscle type interactions were observed for the transcript levels of FABP3, TPM2, and TPM3 (P ≤ 0.05). There was difference for tropomyosin (TPM) protein abundance between muscles only in bulls (P ≤ 0.05), where the greater TPM abundance was in the TB. Additionally, cattle gender status affected the TPM abundance evaluated in LO and TB muscles (P ≤ 0.05). The LO muscle of steers showed higher TPM abundance than bulls and heifers, while the TB muscle of bulls showed higher TPM abundance than the other genders. The cattle gender status modulated the transcripts levels of ACC gene, content of total lipids, total SFAs, total MUFAs, and carcass traits, while the muscle type affected the transcripts of CEBPa and LPL genes, total SFAs, total PUFAs, total n-3 and n-6, besides important FAs, showing a gender and muscle specific effect. In addition, a modulation of TPM in formation and accumulation of lipids was observed, related to the greater subcutaneous fat thickness and marbling score in heifers and steers, and a modulation of this same protein in muscle development, indicated by the lower fat deposition in the carcass of bulls. Furthermore, there is a different lipid profile within each muscle, where the TB muscle is more favorable to human health than the LO, and beef from heifers stands out than the other genders for presenting better carcass traits and FA composition more favorable to human health.A condição sexual dos bovinos influencia o seu crescimento, assim como a formação do tecido adiposo muscular, a composição de ácidos graxos em diferentes músculos e vias de adipogênese, sendo estas influenciadas por uma variedade de sinais hormonais, o que afeta diretamente as características da carcaça e a qualidade da carne. Desta forma, o presente estudo analisou a influência da condição sexual (CS) dos bovinos sobre a expressão dos genes associados à adipogênese, assim como avaliou o perfil de ácidos graxos dos músculos longissimus (LO) e triceps brachii (TB) de bovinos Angus x Nelore. Foram confinados 150 bovinos, divididos em três CS (50 fêmeas, 50 machos não castrados e 50 castrados). O delineamento experimental considerado foi inteiramente casualizado, com 50 repetições por grupo e cada animal foi considerado como uma unidade experimental. Os animais foram mantidos nas mesmas condições de manejo, recebendo alimentação ad libitum utilizando-se a mesma dieta, composta de 86% de concentrado e 14% de volumoso na matéria seca. Após 150 dias de confinamento, os animais foram abatidos aos 16 meses de idade. Durante o abate, imediatamente após a esfola foram coletadas amostras dos músculos LO e TB para extração de RNA e proteína. Durante a desossa foi avaliada a espessura de gordura subcutânea e o escore de marmorização no músculo longissimus, entre a 12ª e 13ª costelas e coletadas amostras dos dois músculos para análise de quantificação de lipídeos totais e composição de ácidos graxos. Os dados estatísticos referentes à qualidade de carcaça e carne foram analisados pelo proc MIXED do programa SAS (versão 9.3) e os referentes aos resultados de expressão gênica pelo programa JMP14® (SAS Institute). A CS afetou as características de carcaça avaliadas (P ≤ 0,05). A espessura de gordura subcutânea e o escore de marmorização foram maiores na carcaça das fêmeas em comparação às dos machos não castrados e castrados. Houve diferença no conteúdo de lipídeos totais somente entre as CS (P ≤ 0,05), com maior conteúdo na carne das fêmeas, seguida da carne dos machos castrados e não castrados. O total de ácidos graxos saturados (AGS) foi influenciado pela CS e pelo tipo de músculo (P ≤ 0,05), sendo que a carne dos bovinos não castrados apresentou maior concentração de AGS do que a carne das fêmeas. O total de AGS no músculo LO foi maior que o TB, independente da CS. Já os ácidos graxos (AG) 14:0 e 16:0 foram afetados apenas pelo tipo de músculo, e concentrações mais elevadas foram detectadas no músculo LO (P ≤ 0,05). O fator CS afetou o total de AG monoinsaturados (AGMI) (P ≤ 0,05), sendo a maior concentração observada na carne de fêmeas e castrados do que na carne de não castrados. Já a concentração do 18:1 n-9c (oleico) foi influenciada pelo tipo de músculo, com maior concentração no músculo LO em comparação ao TB (P ≤ 0,05). Houve efeito do tipo de músculo para o total de AG poli-insaturados (AGPI), total de n-3, total de n-6, proporção AGPI:AGS, os AG individuais 18:2 n-6c, 20:3 n-3, 22:4 n-6 e o índice de saúde. As concentrações foram maiores no TB em comparação ao LO (P ≤ 0,05). Por outro lado, os índices de aterogenicidade e trombogenicidade foram maiores no músculo LO (P ≤ 0,05). Com relação aos níveis de transcritos, houve efeito do tipo de músculo na expressão dos genes CEBPa e LPL (P ≤ 0,05), ambos com maior expressão no músculo TB. Já a CS influenciou o nível de transcritos do ACC (P ≤ 0,05) e o gene foi mais expresso nas fêmeas em relação aos machos castrados. Foi observada interação entre CS e tipo de músculo para os genes FABP3, TPM2 e TPM3 (P ≤ 0,05). Houve diferença na abundância da proteína tropomiosina (TPM) entre os músculos, mas somente dentro da condição sexual machos não castrados (P ≤ 0,05), com maior abundância no músculo TB em comparação ao LO. Adicionalmente, a CS afetou a abundância da TPM avaliada nos músculos LO e TB (P ≤ 0,05). O músculo LO dos machos castrados apresentou maior abundância da TPM do que os machos não castrados e fêmeas, enquanto o TB dos machos não castrados apresentou maior abundância do que as demais CS. A CS modulou os níveis de transcritos do ACC, conteúdo de lipídeos totais, total de AGS, total de AGMI e as características de carcaça, enquanto o tipo de músculo afetou os transcritos dos genes CEBPa e LPL, total de AGS, total de AGPI, total de n-3 e n-6, além de importantes AG, demonstrando efeito especifico da CS e o tipo de músculo. Adicionalmente, foi observada uma modulação da tropomiosina na formação e acúmulo de lipídeos, relacionada a maior espessura de gordura subcutânea e escore de marmorização nas fêmeas e machos castrados, e uma modulação desta mesma proteína no desenvolvimento muscular, apontada pela menor deposição de gordura na carcaça de machos não castrados. Além disso, há um perfil lipídico diferente dentro de cada músculo, onde o TB é mais favorável à saúde humana do que o LO, e a carne bovina de fêmeas se destaca das demais condições sexuais por apresentar melhores características de carcaça e composição de AG mais favorável à saúde humana

Genetic parameter for meat fatty acid profile of Nelore cattle finished in feedlot

The aim of this study was to estimate (co)variance components and genetic parameters (heritability and genetic correlations) for meat fatty acid composition in Nellore cattle. The fatty acids analyzed were: conjugated linoleic acid - CLA (C18:2 trans-10 cis-12), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1 cis-9), linoleic acid (C18:2 cis- 9-12) and linolenic acid (C18:3). A total of 751 Nellore bulls, finished in feedlot for at least 90 days, with average age at slaughter of 24 months were used. The animals belong to eight farms located in the Southeast, Northeast and Midwest regions, of São Paulo State, which comprise three specific genetic breeding programs. The fatty acid determination was carried out at the Laboratory of Meat Science (LCC), Department of Animal Production and Nutrition FMVZ/USP. Samples from theLongissimus muscle were collected 48 hours after slaughter. The determination of meat fatty acid profile was performed by the method of Folch et al. (1957) and Kramer et al. (1997). Fatty acids were quantified by gas chromatography (GC-2010 Plus - Shimadzu AOC 20i auto sampler) using SP-2560 capillary column (100 m × 0.25 mm in diameter with 0.02 mm thickness, Supelco, Bellefonte, PA). To estimate the (co) variance components and genetic parameters, the model included the additive genetic effect as random effect, and the fixed effects of the contemporary group and animal's age at slaughter as a covariable (linear effect). The model used for the estimation of the  included random direct genetic effect, the fixed effect of the GC, and the animal's age at slaughter as a covariate (linear effect).The (co)variance components and genetic parameters were estimated by Bayesian inference with a linear multi-trait animal model, using the GIBBS2F90 program. The convergence of the data was verified using the R software package analyzed with the Bayesian Output Analysis (BOA) of the R 2.9.0 software (The R Development Core Team, 2009). Heritability estimates obtained for the fatty acids analyzed were: 0.52; 0.26; 0.68; 0.57; 0.46 and 0.41 for CLA, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, respectively. The genetic correlation estimates between the palmitic acid (C16: 0) with stearic acid, oleic acid, linoleic acid, linolenic acid and CLA showed the following values: 0.14; 0.39; -0.09; -0.33; 0.34. The genetic correlation estimates between the stearic acid with oleic acid, linoleic acid, linolenic acid and CLA were 0.24, -0.06, -0.21 and 0.22, respectively. For the oleic acid, the genetic correlation estimates were -0.04, -0.02 and -0.02, with the linoleic acid, linolenic acid and CLA, respectively. The genetic correlation estimated between the linolenic acid and CLA was close to zero. Most of the genetic correlations estimates between fatty acids were low to moderate. The heritability estimates for fatty acids were moderate to high, indicating that these traits would respond rapidly to selection. The genetic correlation estimates between fatty acids with different degrees of saturation suggest that indirect selection to improve the meat fatty acid composition is possible