Chemical composition and fatty acids profile on Longissimus muscle of crossbred bulls fed with sugar cane or sorghum silage and finished with 3.4 or 4.8 mm of fat thickness

Abstract

This study was carried out to evaluate the chemical composition and fatty acid profile of Longissimus muscle of cattle from three genetic groups (ZEB - Zebu, LIZ - Limousin vs. Zebu and ANZ - Angus vs. Zebu) fed sorghum silage + 1.0% of body weight of concentrate or sugar cane + 1.2% of body weight of concentrate and were slaughtered at one of two fat thickness levels (3.4 or 4.8 mm fat thickness). Were used 36 bulls with age 21 months and weighing 330 ± 44.0 kg finished in feedlot after 115 or 147 days. There were no differences in moisture content (74.09%), ash (0.99%), protein (21.61%), total lipids (1.69%) and total cholesterol (37.83 mg/100 g of muscle) among the genetic groups and diets. The Longissimus muscle of animals slaughtered at 3.4 mm of fat thickness had higher moisture content (75.40%) and ash (1.03%) when compared to slaughtered 4.8 mm (72.78 and 0.96%, respectively). Genetic groups LIZ showed higher concentrations of eicosapentaenoic acid (0.45%) and omega 3 (0.98%) compared to ZEB (0.18 and 0.62%, respectively) and ANZ (0.25 and 0.70%, respectively). The diet consists of sugar cane resulted in increased deposition of fatty acid palmitoleic (3.07%) in relation to diet composed of sorghum silage (2.57%). This result was obtained due to higher activity of the enzyme ?⁹desaturase C16 in animals fed with sugar cane. Sorghum silage increased the deposition of acid 22:4 n-6 (0.14%) compared to sugar cane (0.10%). The fat thickness levels of the carcasses had no effect on fatty acid composition, except for the ratio omega 6/omega 3. The slaughter of animals with 3.4 mm of fat thickness provided the best ratio omega 6/omega 3 (7.33 vs. 8.63). The chemical composition and fatty acid profile of Longissimus muscle of animals analyzed in this study show little variation in terms of genetic groups, diets and fat thickness levels.