Nutritional characterisation of sheep meat in pastoral system

Mineral, heme iron, vitamin B12 and fatty acid content of longissimus thoracis muscle of different genotypes: Doctoral thesis abstract

Resumo

The content of macroelements, Ca, Mg, Na and K, trace minerals such as Se, Co, Zn, Cu, Mn, total iron (TFe), heme iron (HFe) and non-heme iron (NHFe) and vitamin B12 and the fatty acid composition of the glycerolipids and glycerophospholipids of the longissimus thoracis muscle were determined. The animals were bred from different genetic biotypes produced in Uruguay, Merino Dohne (MD), Highlander® (H), Corriedale Pro (CPRO), Corriedale (C), Australian Merino x Corriedale cross (CxMA). The animals were all under the same conditions on pasture. The Merino Dohne breed had the highest calcium concentration (66.6±6.3 mg.kg^-1), Highlander and Merino Dohne had significantly (P<0.05) higher manganese concentrations (304.1±26.0 and 308.7±23.6 µg.kg^-1 g, respectively) than the other breeds. There were no significant differences in vitamin B12 concentrations among the breeds of lambs. The HFe and HFe/TFe ratio was higher (P<0.05) in the Corriedale and Corriedale Pro breeds (15.7±0.6 and 15.4±0.7 mg.kg^-1 and 81.7±2.8% and 76.0±2.2%, respectively) and, consequently, lower NHFe, relative to the other groups. A higher Zn content was also obtained in Corriedale (32.6±1.3 mg.kg^-1). The results showed no substantial differences between breeds in the fatty acid composition of the meat, except for relevant fatty acids such as C16:0 (MD, C), C18:3n3 (H, C) and CLA (H, CPRO, CxAM) for glycerolipids. Also, C18:1 (H, CPRO and CxAM), C18:2n6 (H, CxAM) and C18:3n3 (H, C) for glycerophospholipids. There are also other differences, such as anteiso fatty acid content (RM, MD) and the ratio of hypocholesterolemic/hypercholesterolemic index (MD, C). MD showed lower Δ-9 desaturase enzyme for fatty acid metabolism activities for C16:0 than C, CPRO and CxAM. In addition, H showed lower Δ-6 desaturase enzyme activity than C, and both MD and CxAM showed lower elongase enzyme activity than C.