Excessive flavour in lamb meat is undesirable for consumers and can prompt purchase resistance. Volatile indoles responsible for off-flavours accumulate more in the fat of lambs on pasture than on grain and are enhanced when lambs graze alfalfa. Here, we investigated whether barley supplementation of lambs grazing alfalfa influences meat sensory quality. Using three groups of 12 male Romane lambs, we compared three feeding regimes: alfalfa grazing (AG), alfalfa grazing + daily supplementation with barley (29 g/kg live weight0.75, AGS) and stall feeding with concentrate and hay (SF). As some of the compounds involved in meat sensory traits may act as dietary biomarkers, we also investigated potential implications for meat authentication. Although barley represented 38% of the diet in AGS lambs, it did not offer any advantage for animal average daily gain or parasitism level. Animal performance, carcass weight and fatness did not differ between feeding regimes. Dorsal fat firmness tended to be greater in AG than AGS and greater in AGS than SF. Skatole and indole concentrations in perirenal and dorsal fat were lower in SF lambs than in AG and AGS lambs (P<0.01 to P<0.0001), but did not differ between AG and AGS lambs. Yellowness, chroma and hue angle of perirenal fat were lower in SF lambs than in AG and AGS lambs (P<0.001), but did not differ between AG and AGS lambs. Absolute value of the mean integral for both perirenal fat and subcutaneous caudal fat (AVMIPF and AVMISC), quantifying the intensity of light absorption by carotenoids in perirenal and subcutaneous caudal fat, respectively, were lower in SF lambs than in AG and AGS lambs (P<0.0001 for both comparisons), but did not differ between AG and AGS lambs. Meat colour was unaffected by the treatment. We confirm that lambs grazing alfalfa accumulate high levels of volatile indoles in their fat, but we show that barley supplementation to lambs grazing alfalfa is not effective in reducing fat volatile indoles concentration and excessive odour/flavour in the meat. We also confirm that both perirenal fat skatole concentration and AVMIPF are of interest for discriminating lambs that grazed alfalfa from lambs that were stall-fed, and we show that they are not effective for discriminating supplemented from non-supplemented grazing lambs.

Avaliou-se como o padrão de deslocamento e de utilização de estações alimentares podem ser afetados por alturas de manejo de 4, 8, 12 e 16 cm numa pastagem nativa. Utilizou-se um delineamento inteiramente casualizado, com quatro tratamentos e duas repetições no tempo e no espaço. Os animais experimentais foram avaliados por meio de testes de pastejo de 45 minutos, para determinação dos número de bocados, número de estações alimentares e número de passos, utilizando-se contadores, com exceção do número de bocados, que foi registrado pelo aparelho IGER Behaviour Recorder. Observou-se correlação positiva entre altura do pasto e massa de forragem e correlação negativa entre alturas do pasto e densidade de forragem. As variáveis avaliadas diferiram entre bezerras e ovelhas. O número de estações alimentares por minuto diminuiu de forma quadrática com o aumento da altura do pasto. O número de bocados por estação alimentar visitada e o tempo por estação alimentar aumentaram de forma quadrática com o aumento da altura do pasto e foram afetados negativamente pela baixa densidade de forragem nos estratos superiores das maiores alturas do pasto. Na altura de 12 cm, as bezerras executaram mais bocados por estação alimentar e permaneceram mais tempo em cada estação alimentar; o mesmo foi observado na altura de 8 cm para as ovelhas. À medida que menos estações alimentares foram utilizadas, como resposta às variáveis anteriores, os animais andaram mais a passos mais lentos. Em alturas do pasto entre 8 e 12 cm, os animais permanecem mais tempo pastejando nas estações alimentares e percorrem distâncias maiores à procura de novos locais para o pastejo.

The present study was conducted to assess carcass features, physicochemical and sensory parameters of meat from steers finished on three types of pastures: natural pasture; natural pasture improved, fertilized and oversown with winter species; and annual summer grassland. The experiment was conducted from December 14, 2009 to November 30, 2010, with treatments distributed in a completely randomized design with a different number of replicates. Animals were used as experimental units. Experimental animals were Aberdeen Angus steers with twenty months of initial age and 354±27.4 kg of live weight, on average. The highest average daily gains were obtained for the annual summer grassland. There was no effect of treatments on carcass conformation. The highest carcass yield was obtained on the improved natural pasture. Forequarter yield, side cut yield and longissimus muscle area were similar between the pastures. Moisture and total lipids were not affected by the pasture. Thawing and cooking losses were higher in improved natural pasture and lower in sorghum pasture. Regardless of the treatment, the meat had luminosity ranging from intermediate to dark, high in red, high in yellow, and considered within the normal range for beef. Meat of higher shear force was found in natural pasture, and lower shear force was observed in meat from annual summer grassland. Average live weight daily gain explained 18% of the shear force. Sensory evaluation by duo-trio test showed differences between samples from distinct pastures in flavor. All the studied systems allow for desirable characteristics in carcass and meat