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Submitted 2020-07-24 | Accepted 2020-09-16 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.282-289 A common practice to improve meat quality is aging under controlled conditions, which results in improved tenderness, a key factor in the consumer acceptance of beef meat. Among other traits, the tenderness and the effect of ageing are also genetically determined. Therefore, a trial was performed to assess the effect of ageing in the progeny of young bulls included in the routine breeding program for Simmental breed in Slovenia. In the trial, 127 young bulls were included, and the shear force of grilled Longissimus thoracis muscle was measured fresh and after three weeks of ageing. There was a significant difference between the fresh and aged muscle in shear force, but growth and other carcass traits did not affect it as it was expected. We assume that after enlarging the number of animals, the data will be usable to be included in the genetic evaluation of the breeding program for Simmental breed in Slovenia. Keywords: Longissimus thoracis, beef, ageing, shear force References Carvalho, M. E. et al. (2014). Heat shock and structural proteins associated with meat tenderness in Nellore beef cattle, a Bos indicus breed. Meat Science, 96, 1318-1324. https://doi.org/10.1016/j.meatsci.2013.11.014 Dikeman, M. and Devine, C. (2014). Encyclopedia of Meat Sciences. Academic Press. Dikeman, M. E. et al. (2005). Phenotypic ranges and relationships among carcass and meat palatability traits for fourteen cattle breeds, and heritabilities and expected progeny differences for Warner-Bratzler shear force in three beef cattle breeds. Journal of Animal Science, 83, 2461-2467. https://doi.org/10.2527/2005.83102461x Florek, M. et al. (2007). Changes of physicochemical properties of bullocks and heifers meat during 14 days of ageing under vacuum. Polish Journal of Food and Nutrition Sciences, 57(3), 281–287. Hanzelkova, S. et al. (2011). The effect of breed, sex and aging time on tenderness of beef meat. Acta Veterinaria Brno, 80, 191-196. https://doi.org/10.2754/avb201180020191 Harper, G. S. (1999). Trends in skeletal muscle biology and the understanding of toughness in beef. Australian Journal of Agricultural Research, 50, 1105-1129. https://doi.org/10.1071/AR98191 Holloway, J. W. and Wu, J. (2019). Tenderness Intrinsic Character. In: Red Meat Science and Production. Springer, Singapore. https://doi.org/10.1007/978-981-13-7860-7_5 Koohmaraie, M. et al. (2002). Meat tenderness and muscle growth: Is there any relationship? Meat Science, 62, 345-352. https://doi.org/10.1016/S0309-1740(02)00127-4 Lawrence, T. E. et al. (2001). Evaluation of electric belt grill, forced-air convection oven, and electric broiler cookery methods for beef tenderness research. Meat Science, 58(3), 239–246. https://doi.org/10.1016/S0309-1740(00)00159-5 Miller, M. F. et al. (1995). Retail consumer acceptance of beef tenderized with calcium chloride. Journal of Animal Science, 73, 2308-2314. https://doi.org/10.2527/1995.7382308x Purslow, P. P. (2005). Intramuscular connective tissue and its role in meat quality. Meat Science, 70, 435-447. https://doi.org/10.1016/j.meatsci.2004.06.028 Sazili, A. Q. et al. (2004). The effect of altered growth rates on the calpain proteolytic system and meat tenderness in cattle. Meat Science, 66, 195-201. https://doi.org/10.1016/S0309-1740(03)00091-3 Shackelford, S. D., Koohmaraie, M. and Wheeler, T. L. (1995). Effects of slaughter age on meat tenderness and USDA carcass maturity scores of beef females. Journal of Animal Science, 73, 3304-3309. https://doi.org/10.2527/1995.73113304x Splan, R. K. et al. (2002). Estimates of parameters between direct and maternal genetic effects for weaning weight and direct genetic effects for carcass traits in crossbred cattle. Journal of Animal Science, 80(12), 3107-3111. https://doi.org/10.2527/2002.80123107x Wall, K. R. et al. (2019). Grilling temperature effects on tenderness, juiciness, flavor and volatile aroma compounds of aged ribeye, strip loin, and top sirloin steaks. Meat Science, 150, 141–148. https://doi.org/10.1016/j.meatsci.2018.11.009 Wulf, D. M. et al. (1996). Genetic influences on beef Longissimus palatability in Charolais- and Limousin-sired steers and heifers. Journal of Animal Science, 74, 2394-2405. https://doi.org/10.2527/1996.74102394x Yancey, J. W. S., Wharton, M. D. and Apple, J. K. (2011). Cookery method and end-point temperature can affect the Warner-Bratzler shear force, cooking loss, and internal cooked color of beef longissimus steaks. Meat Science, 88, 1–7. https://doi.org/10.1016/j.meatsci.2010.11.020 Zwambag, A. et al. (2013). Heritability of beef tenderness at different aging times and across breed comparisons. Canadian Journal of Animal Science, 93, 307312. https://doi.org/10.4141/CJAS2012-100

The aim of the present study was to evaluate the effect of different production systems on fatty acids (FA) composition of three beef muscles (longissimus thoracis, semitendinosus and diaphragmae). The first group (MGSC) included 8 bulls of Slovenian Brown breed that were fattened with maize, grass silage and concentrates. The second group (MCS) included 8 bulls of Slovenian Simental breed that were fattened with maize silage, ensiled corn grain and concentrates. The third group (GS) included 6 Limousine × Simmental crossbreed bulls that have been fattened on pasture in cow-calf production system until slaughter. In fourth group (G) 8 bulls of Slovenian Simmental breed were fattened on pasture from spring to autumn when they were slaughtered. Bulls from MSC and MGSC had similar carcass weight (316 kg, 308 kg, respectively), whereas bulls from GS had the lightest (215 kg) and bulls from G the heaviest carcass weight (371 kg). Carcass fatness was similar for bulls in MSC, MGSC and G groups and slightly lower in GS group. The percentage of saturated FA differed among groups only in semitendinosus muscle. Bulls from G and GS had lower percentage of monounsaturated FA (MUFA) and higher percentage of polyunsaturated FA (PUFA) in all three muscles. Bulls from grazing production systems had higher n-3 PUFA values in all muscles and higher n-6 PUFA values in semitendinosus and diaphragmae. Bulls fattened on pasture had lower n-6/n-3 ratio in all three muscles. Bulls from GS had a higher percentage of conjugated linolenic acid in comparison to MGSC and MCS groups in all muscles except in semitendinosus where percentage of CLA was higher only from MGSC group.

The aim of the study was to determine fatty acid composition in meat of Cika and Simmental bulls from two different fattening technologies. The herd of 39 young bulls was housed during the winter time and fed the same total mixed ration diet (TMR) based on corn and grass silage with a limited amount of concentrates. In the spring bulls of both breeds were divided into two subgroups. Bulls in the first subgroup (10 Cika, 9 Simmental; S-INT) were fattened indoors with the semi-intensive TMR. Bulls in the second subgroup (10 Cika, 10 Simmental; G+S-INT) were put on all-day grazing in the pasture. After grazing period bulls were housed under the same conditions as the first subgroup. Samples of M. longissimus dorsi were collected from the right carcass side to determine the total fat content and the fatty acid composition. The breed significantly influenced fatty acid composition in meat. The beef of Simmental bulls resulted in higher percentage of PUFA and lower percentage of SFA and MUFA. Higher percentage of n-3 and n-6 PUFA was determined in meat of Simmental bulls but the n-6/n-3 ratio was lower in Cika bulls meat. The fattening technology had less effect on FA composition in meat. The second grazing period produced higher percentage of SFA, beneficially lower values of n-6/n-3 ratio and higher values of long-chain C20-22n-3 PUFA. Higher CLA percentage was determined in beef from S-INT group.

1. This study examined the effect of α-tocopherol (α-T), sweet chestnut wood extract (SCW) and their combination on oxidative stress in vivo and oxidative stability of meat in broilers given diets rich in PUFA. 2. A total of 60 male broilers were individually caged and divided into 6 groups of 10. The C-PALM group received a diet with 7·5% palm fat and the other 5 groups with 7·5% linseed oil. The linseed oil groups were either un-supplemented (C-LIN) or supplemented with α-T or/and SCW as follows: αT-85 (C-LIN diet + 68 IU vit E as all-rac-α-T/kg), αT-200 (C-LIN diet + 183 IU vit E as all-rac-α-T/kg), SCW (C-LIN diet + 3 g SCW/kg) and αT-SCW (C-LIN diet + 68 IU vit E as all-rac-α-T/kg + 3 g SCW/kg). Different parameters of oxidative stress were measured. 3. Linseed oil induced DNA fragmentation and malondialdehyde (MDA) formation, while α-T reduced both parameters, and SCW reduced the DNA damage. A combination (αT-SCW) also reduced plasma MDA. Larger antioxidant capacity of lipid soluble compounds were recorded in groups αT-85, αT-200 and αT-SCW than in the controls but there were no differences between these groups in antioxidant enzymes and total antioxidant status. A combination (αT-SCW) increased tocopherol concentrations in breast muscle and in comparison to the C-LIN group MDA concentrations were reduced in groups αT-85, αT-200 and αT-SCW. 4. It can be concluded that neither of the α-T concentrations were able to prevent all the negative effects of lipid oxidation in vivo and only high concentrations of α-T improved the stability of meat. With the exception of DNA damage, SCW had no impact on in vivo and in vitro measured markers of oxidative stress but may have a sparing or regenerating effect on α-T.

The aim of this study was to compare recommendations for vitamin E supplementation regarding high polyunsaturated fatty acid intake and to compare the bioactivity of RRR- and all-rac-α-tocopherol with respect to oxidative stress in vivo and the oxidative stability of broiler meat. Fifty male broilers were divided into 5 groups. All groups received diets with a high inclusion of fat (7.5%), one with palm fat and the others with linseed oil, which were either unsupplemented or supplemented with vitamin E to contain in total 85 or 200 IU of vitamin E as all-rac-α-tocopherol and 85 IU as RRR-α-tocopherol. Oxidative stress in vivo was studied by measuring the DNA damage; measuring malondialdehyde (MDA) in plasma, liver, and breast muscle; and analyzing the antioxidant capacity of the lipid-soluble compounds, total antioxidant status of plasma, and antioxidant enzyme assays. The tocopherols in plasma, liver, and breast muscle were also analyzed. In vitro oxidative stability was studied by measuring MDA in fresh, stored, and heat-treated breast meat. Linseed oil, as opposed to palm fat, induced DNA fragmentation and MDA formation. Both forms and concentrations of vitamin E reduced DNA damage and breast muscle MDA. The groups receiving 200 IU of all-rac-α-tocopherol and 85 IU of RRR-α-tocopherol had much higher values for antioxidant capacity of lipid-soluble compounds than did the controls. No differences were observed in the values of antioxidant enzymes. The α-tocopherol levels in tissues and plasma were significantly influenced by the level of α-tocopherol supplementation. Malondialdehyde formation in meat from the vitamin E-supplemented groups was decreased in comparison with that from the control linseed oil group. We conclude that both vitamin E concentrations were insufficient to prevent all harmful effects of lipid oxidation in vivo and that both were equally effective. On the contrary, to ensure good stability of meat lipids, higher vitamin E supplementation is needed, especially after heat treatment. The results of in vivo oxidative stress and meat lipid oxidation confirmed the currently accepted bioactivity of the RRR-α- to all-rac-α-tocopherol ratio of 1.39 in in vivo and in vitro systems.

The objective of the present study was to determine the effect of linseed oil supplementation on performance, fatty acid composition and oxidative status of rabbits. Twelve male SIKA rabbits were divided into two groups. The control group (n = 4) received commercial diet and the linseed group (n = 8) received commercial diet containing 9% of linseed oil, which was sprayed onto the pellet. Rabbits were slaughtered at 115 days of age, 52 dazs after the start of the experiment. Live weight, weight gain, feed intake and feed efficiency were recorded. The fatty acid composition of muscle, adipose tissue and liver was determined by the in situ transesterification method and gas chromatography-flame ionisation detection (GC-FID). In order to evaluate the oxidative status of rabbits, the malondialdehyde (MDA) concentration in plasma, liver and muscle were measured. The results show that it is possible to enhance proportion of n-3 polyunsaturated fatty acids (PUFA) in rabbit's muscle, adipose tissue and liver by adding linseed oil in the diet without detrimental effect on productive performance. Linseed oil addition improved fatty acid composition in all tissues by increased PUFA proportion and decreased proportion of saturated and monounsaturated fatty acid. Linseed oil also reduced n-6/n-3 PUFA ratio in all tissues. However, linseed oil addition led to significantly higher MDA concentrations in plasma, liver and muscle. Since PUFA are highlz susceptible to oxidation, further research is needed to focus on protecting animal and their products from lipid oxidation by adding various natural antioxidants to the diet. V poskusu smo preučevali vpliv dodatka lanenega olja v krmo na proizvodne lastnosti, maščobnokislinsko sestavo in oksidacijski status kuncev. Dvanajst kuncev slovenske mesne linije SIKA smo razdelili v dve skupini. Kontrolna skupina (n = 4) je uživala standardno krmo, poskusna skupina (n = 8) pa standardno krmo z dodatkom 9 % lanenega olja, ki smo ga nanesli na pelete. Kunce smo zaklali pri starosti 115 dni, 52 dni po začetku poskusa. V času poskusa smo zapisovali maso živali, prirast, zauživanje in izkoristek krme. Maščobnokislinsko sestavo mišic, maščobnega tkiva in jeter smo določili z in situ transesterifikacijo in kapilarno plinsko kromatografijo. Za določitev oksidacijskega statusa kuncev smo izmerili koncentracijo malondialdehida (MDA) v plazmi, jetrih in mišici. Rezultati so pokazali, da lahko z dodatkom lanenega olja v krmo kuncev povečamo dele n-3 večkrat nenasičenih maščobnih kislin (VNMK) v mišici, maščobnem tkivu in jetrih brez negativnih učinkov na proizvodne lastnosti. Dodatek lanenega olja je izboljšal maščobnokislinsko sestavo s povečanjem deleža VNMK in zmanjšanjem deleža nasičenih in enkrat nenasičenih maščobnih kislin, kar je znižalo tudi razmerje n-6/n-3 VNMK v vseh tkivih. Dodatek lanenega olja je značilno povečal koncentracijo MDA v plazmi, jetrih in mišici. Ker so VNMK zelo podvrene oksidaciji, so potrebne nadaljnje raziskave, v katerih se bo potrebno osredotočiti na zaščito živali in njihovih produktov pred lipidno oksidacijo z dodajanjem različnih naravnih antioksidantov v krmo.