Fatty acid levels in the muscle tissue of eight beef cattle breeds

The objective of the study was to compare the chemical composition and fatty acid profile in ten clinically healthy bulls of similar weight from eight meat cattle breeds. The animals were raised by extensive grazing under the same geographical conditions. Significant differences were observed between the monitored genotypes in terms of the dry matter content, nitrogenous matter and fats (P ≤ 0.05) in the musculus longissimus thoracis. The concentration of fats ranged from 68.5 ± 18.81 g (Galloway cattle) to 171.6 ± 43.3 g (Aberdeen Angus) per kg of dry matter. The total content of unsaturated fatty acids ranged from 20.0 ± 2.25 g (Aberdeen Angus) to 42.4 ± 7.87 g (Gascon); the total sum of monounsaurated fatty acids ranged from 17.0 ± 2.26 g (Aberdeen Angus) to 33.8 ± 3.61 g (Gascon); and the total sum of polyunsaturated fatty acids ranged from 3.0 ± 1.42 g (Aberdeen Angus) to 5.1 ± 3.99 g (Limousin) per 100 g of fat. The total content of n-6 fatty acids ranged from 2.4 ± 1.28 g (Aberdeen Angus) to 4.2 ± 3.59 g (Limousin) and the total content of n-3 fatty acids from 0.5 ± 0.16 g (Salers) to 1.1 ± 0.04 g (Gascon) per 100 g of fat. The properties we studied may predict the biological, dietetic, and culinary value of the meat. Musculus longissimus thoracis, MUFA, PUFA, n-6 PUFA, n-3 PUFA Along with vegetable oils, lipid sources in human nutrition also include fats of animal origin. Findings regarding the presence of fatty acids in vegetable and animal fats have nutritional, dietary and health implications for both people and animals. These effects include the physiological functions of fats in the living organism as well as the functions of individual fatty acids (FA) in the study of diets and in the prevention and treatment of diseases related to a temporary deficiency or increased intake. In this regard, attention is also given to the lipid component in beef (Scollan et al. 2006), where the need to increase the ratio of n-3 polyunsaturated fatty acids (PUFA) has been emphasized (Griel et al. 2006; Kris-Etherton 2007). It is generally accepted that the concentration of FA in the meat of food animals significantly depends on the content of their diet (Aldai et al. 2008). Several authors (Enser et al. 1998; Duynisveld et al. 2006; Ponnampalam et al. 2006; Garcia et al. 2008; Smith et al. 2009; Daley et al. 2010; Yüksel et al. 2012; Turner et al. 2015) have studied the presence of FA in beef in relation to the diet. These studies compared diets based on grazing and grain-fed beef. Grazing increased the amount of the precursors of vitamins A and E, as well as antioxidants such as glutathione and superoxide dismutase (Daley et al. 2010). In particular, vitamin E maintains the PUFA concentration in beef and contributes to ensuring its quality during processing (Wood et al. 2004). Calf meat on pasture had a higher percentage of saturated fatty acids (SFA), PUFA and n-3 PUFA and a lower percentage of intramuscular fat, monounsaturated fatty acids (MUFA), and n-6 PUFA than animals that were fed with corn while grazing or fed a dose of corn, soybean ACTA VET. BRNO 2018, 87: 285-291; https://doi.org/10.2754/avb201887030285 Address for correspondence: Prof. Ing. Eva Straková, Ph.D. University of Veterinary and Pharmaceutical Sciences Brno Faculty of Veterinary Hygiene and Ecology, Department of Animal Nutrition Palackého tř. 1946/1, 612 42 Brno, Czech Republic Phone: +420 541 562 672 E-mail: strakovae@vfu.cz http://actavet.vfu.cz/ and alfalfa (Garcia et al. 2008). Yüksel et al. (2012) discovered that a diet based on grazing had a favourable impact on the FA profile in meat. However, the resulting meat was darker and tougher. The relationships between cattle breeds, their nutrition, the presence of fatty acids in intramuscular fat and the quality of meat have been studied by various researchers (Holló et al. 2001; Dannenberger et al. 2003; Raes et al. 2003; Garcia et al. 2008; Xie et al. 2012; Liu et al. 2015). For example, Garcia et al. (2008) report that the diet had a greater influence on the composition of the fatty acids of intramuscular fat than the breed. In three breeds (Holstein, Simmental, and Chinese LongDong Yellow Cattle), Liu et al. (2015) proved that the presence of fatty acids differed in fat of the musculus longissimus thoracis and in kidney fat. In contrast, Holló et al. (2001) stated that the proportion of saturated, monoand polyunsaturated FA were not significantly influenced by the breed (Hungarian Simmental, Holstein-Friesian) or by live weight. Intramuscular fat in beef is very important in terms of taste and tenderness; especially its intercellular ratio, which is divided between muscle fibre in vein-like patterns and forms the so-called marbled meat (Steinhauser et al. 2000). Lipophilic substances, which are released with heat and contribute to the meat’s smell and taste (Ingr 2011), are contained in the muscle fat. Jiang et al. (2011) observed the effect of fatty acids, noting a negative influence on the meat’s taste for eicosapentaenoic acids (C20:5n3). Literary data on the presence of FA in the fat of modern beef cattle breeds are hard to find, and a comparison of several breeds with the same diet, same husbandry practices, and in a single location is very rarely done. The presented work should contribute to existing knowledge and attest whether different genotypes of cattle raised by extensive grazing under the same geographical conditions influence the chemical composition of the fat component (especially in relation to the presence of individual groups of FA) in the muscles of contemporary breeds. Materials and Methods The subject of observation was eight beef cattle breeds recognized in the Czech Republic: Aberdeen Angus (AA), Blonde d’Aquitaine (BA), Limousin (Lim), Gascon cattle (Gas), Meat Simmental (MS), Salers (Sal), Galloway cattle (Gall) and Czech multi-colored (Čs). Animals of the selected breeds were raised in the same region of Southern Bohemia (Křišťanov) by extensive grazing. Their diet was based on the intake of grasslands, and their winter diet consisted of hay and straw. Ten clinically healthy bulls of similar weight between the ages of 16 to 18 months were chosen from each beef cattle breed. After slaughtering, a 500-g muscle sample was taken from the musculus longissimus, pars thoracis. The samples were taken from the left half of the body between areas 1 to 10 of the thoracic vertebrae, then the samples were chilled, frozen and gradually analyzed. The muscle samples were provided by the producer ZEFA Volary, Czech Republic. The dry matter, nitrogenous matter, fat, gross energy (AOAC 2006) and fatty acids were determined in a laboratory. The muscle sample was homogenized, dried at 105 °C under prescribed conditions, and the dry matter was determined. The content of nitrogen was determined using the Kjeldahl method on a Buchi analyzer (Centec automatika, Czech Republic), and the content of nitrogenous matter (crude protein) was calculated by multiplying the value of nitrogen by the coefficient of 6.25. Fat was determined by the ANKOMXT10 Fat Analyzer (O.K. SERVIS BioPro, Czech Republic). Combusted heat was determined by a combusted sample in the calorimetric bomb in an oxygen atmosphere in the Leco (USA) calorimeter. The extraction of fat from the muscle to determine fatty acids was performed according to Hara and Radin (1978). In addition, the standard ČSN EN ISO 129661, 12966-2 was used. Fatty acid esters were detected by gas chromatography using a Gas Chromatograph GC2010 analyzer (Shimadzu, Japan) with a flame ionisation detector and evaluated in the GC PostRun program. Some fatty acids in the muscle sample reached very low values below the detection limit, therefore only certain selected fatty acids were monitored. Samples were converted to the content of the given fatty acid in the sample (g/100 g of fat). To ensure more accurate reproducibility, all the results are presented in muscle dry matter (g/kg of dry matter). The obtained results were processed by the statistical program Unistat CZ version 5.6 for Excel, in which the mean values and their differences were evaluated by multiple comparison by Tukey-HSD test at the significance level of P ≤ 0.05. 286