The effect of corn supplementation on α-tocopherol concentration and oxidative stability in three muscles of grass-fed Holstein bulls

Abstract

Context Lipids are important in improving the flavour and aroma of beef and increasing its tenderness and juiciness. However, it is generally accepted that lipid oxidation is the main process responsible for deterioration of meat quality during storage. Naturally occurring antioxidants in pasture play an important role in protecting beef from oxidation. Aims The effects of feeding Holstein bulls grass alone or grass supplemented with high-energy ground corn on α-tocopherol content and oxidative stability of beef were investigated. Methods Thirty-three Holstein bulls, 15 months of age, fed grass alone after weaning were randomly divided into three groups and fed for 85 days as follows: (1) grass ad libitum only, (2) grass ad libitum and supplemented with 4 kg/day ground corn; (3) grass ad libitum and supplemented with 8 kg/day ground corn. Samples from three different muscles, longissimus thoracis, semitendinosus and supraspinatus, were analysed for α-tocopherol content and two oxidation parameters: reactive thiobarbituric acid substances (TBARS) and ferric reducing antioxidant power (FRAP). Key results Levels of α-tocopherol ranged from 2.7 to 3.1 μg/g in beef from animals fed only grass, whereas levels of 1.9–2.5 μg/g were observed in beef from animals supplemented with ground corn. Inclusion of corn in the bulls’ diets resulted in lower α-tocopherol and FRAP levels (P < 0.05) and higher TBARS content (P < 0.05) in the three muscles studied. Conclusions Supplementation of grass-fed bulls with ground corn resulted in muscles having less vitamin E and a reduced antioxidant capacity. Implications To produce high-quality beef, grass-fed Holstein cattle should be fed high-energy forages such as corn. However, this supplementation decreases the oxidative stability of the meat, most likely due to a reduction in the amount of α-tocopherol ingested via the grass.