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The influence of sire selection index on the intramuscular fat fatty acid profile of their progeny

The nutritional value of beef meat is related to its fatty acid composition and the amount of intramuscular fat (IMF). In a two-year experiment, 50 steers sired by five Simmental sire with different selection indices (SI) were used to evaluate the effects of sire on carcass characteristics and fatty acid composition. To test the variability in measured parameters among fattening bulls, they were divided into three groups according to EUROP conformation class and EUROP fat grade. Protein content of longissimus dorsi (LD) linearly increased with increasing SI, while LD fat decreased. All important fatty acid (FA) varied significantly among different sires ; nevertheless these differences were not related to sire SI. Live weight, cold carcass weight, C18:1n9, monounsaturated fatty acids (MUFA) and 18:1/18:0 ratio increased with increasing EUROP conformation score, while C20:4n6 and saturated fatty acids (SFA) decreased. Higher EUROP fat grade was related to increase in cold carcass weight, % of total lean meat, C18:1n9, MUFA and C18:1/C18:0 and decrease in % total bone, SFA, C18:3n3 and C20:4n6. Polyunsaturated fatty acid content was positively correlated to LD protein content and negatively correlated to MUFA content. Principal component analyses revealed that polyunsaturated fatty acids (PUFA) and n6/n3 ratio are directly opposite to MUFA content. Parameters that represent negative impact on health are independent and in opposition to PUFA and MUFA content. These results suggested a genetic variation in FA synthesis and IMF content among progeny of different sires which may enable us to select for increased PUFA content and decreased health lipid indices and potentially atherogenic fatty acids.

fatty acid ; chemical composition ; genetic variation ; beef ; sire

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