Isótopos estáveis para traçabilidade e qualidade de carne de cordeiro

Abstract

Analytical and non-invasive methods and inert animal health capable of identifying the feed provided to sheep are necessary, since in addition to acting as physical markers of the diet, detecting what was actually provided to the animals, still allows leverage the productive chain, providing greater visibility the final quality of the products. The objective of this study was to use stable isotopes of carbon and nitrogen to determine the diets supplied to lambs, in vivo and postmortem, by analysis of wool, blood and feces and meat, describing which sample is most suitable for traceability and in addition, the effect of diets on the quality of the meat. The experiment was carried out at the Ovinocultura Laboratory of the Federal University of Santa Maria (UFSM). Twenty-two uncastrated male lambs were randomly distributed in 2 finishing systems, with 4 distinct diets, with eight replicates in each: Rapegrass (Lolium multiflorum), characterizing the diet C3; Confinement of Tifton Hay (Cynodon spp.) + Maize (Zea mays), exclusively for the C4 diet; (Alya sativa) confinement with soybean meal (Glycine Max) and confinement of Alfalfa Hay (Medicago sativa), ad libitum, both with exclusive diets C3. The animals were kept confined until they obtained 30 kg of live weight. The identification of the diets by the analysis of stable isotopes of carbon (δ13C) was determined by analysis of wool, blood and faeces collected every 15 days and later analyzed in the mass spectrometer of isotopic ratios. After the slaughtering, the meat isotopic and sensorial analyzes were carried out by trained panel of ovine meat. The experimental design was completely randomized, in a factorial scheme. There was complete isotope differentiation of diets. Thus the stable isotope analysis of δ13C and δ15N is an effective tool for traceability. Through the δ13C and δ15N isotopes, the diets characterized with C3 and C4 plants, as well as food, pasture and confinement systems were differentiated. The variation of δ13C determines enriched or depleted foods of δ13C. The C4 species present a relative δ13C enrichment, differing significantly from the treatments, with C3 diets. The analysis of the δ15N allowed to distinguish the separation of the systems, in this way the system composed by Azevém pasture presents a higher natural concentration of 15N. Therefore, the isotopic values of δ13C and δ15N allow differentiation and certification of diets and sheep production systems, demonstrating slow dietary markers such as wool and faithful diets such as faeces. For sensorial analysis 32 samples were used, 8 per treatment, samples from the cut of longissimus dorsi. The evaluations were carried out by a group of 11 trained people, who were instructed to describe the perceived attributes. The quality of animas meat in ryegrass pasture stands out because it presents the lowest lipid content and recommended protein content for sheep meat. The sensory attributes of the flesh were influenced directly by the termination systems. The acceptability of the judges, proves the preference of meat consumption to pasture. The most characteristic characteristic odor is present in the meat of the animals fed on ryegrass pasture, while the meat of the animals confined with maize presents the greatest softness.