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The purpose of this experiment was to determine the extent to which lamb carcass quality and fat composition could be altered by applying a dry olive cake-based ration instead of a conventional ration or pasture feeding. Three treatments were compared in a completely randomized experiment using 36 single male Suffolk Down lambs with an initial age and live weight of 80 d and 25 kg, respectively. The three treatments were: (a) suckling lambs kept with their mothers on annual Mediterranean grassland (GRAZE); (b) weaned stall-fed lambs on a control ration (CONC); and (c) weaned stall-fed lambs on an olive cake-based ration (CAKE). At the end of the 28-d experimental period, lambs were slaughtered, carcass quality evaluated, and samples of subcutaneous fat analyzed for fatty acids. Treatments did not differ in weight gain or carcass weight and quality, but highly significant differences were found in several fatty acid contents. CAKE animals had reduced palmitic acid as well as increased oleic and stearic acid contents. Atherogenic and thrombogenic indices improved with cake feeding. Principal component and discriminant analyses clearly differentiated treatments suggesting they could be applicable for traceability purposes. A laboratory experiment demonstrated that with or without added vitamin E, the dry olive cake did not alter its lipid properties with increased storage time.

R.R. Vera, C. Aguilar, and R. Lira. 2009. Differentiation of sheep milk and cheese based on their quality and composition. Cienc. Inv. Agr. 36(3):307-328. Traditional sheep production for meat and wool for meat and wool among small and medium-sized Chilean farmers has low profi tability. Therefore, there is interest in producing value-added, differentiated products. One alternative is the production of sheep milk and cheese. This article analyzes and discusses existing alternatives for modifying milk and cheese compositions with the aim of differentiating these products. Also, analytical techniques that allow the chemical characterization of milk and cheese are briefl y mentioned. The main international thrusts are focused on the modifi cation of the content and composition of milk fatty acids and on the identifi cation of volatile compounds, terpenes, polyphenols and other analytes that allow differentiation of cheese types on the basis of aroma, taste and fl avor and that would help in ensuring traceability.

RESUMENEfecto de la inclusión de aceite de oliva lampante en la dieta de ovejas sobre el perfil de ácidos grasos de leche y queso El objetivo de este estudio fue evaluar el efecto de la inclusión de aceite de oliva lampante en la dieta de ovejas sobre el perfil de ácidos grasos de leche y queso. Nueve ovejas fueron utilizadas en un diseño de CuadradoLatino 3 × 3. Las dietas fueron suplementadas con 0 (control; T0), 36 (T1) y 88 (T2) g de aceite de oliva lampante por kg de materia seca de alimento. La ingesta, la producción de leche y la composición de leche (grasa y proteína) no se vieron afectados por los tratamientos. Los ácidos oleico y vaccénico incrementaron (P < 0.05) gradualmente mientras que los ácidos grasos saturados y el índice aterogénico disminuyeron (P < 0.05) en leche y queso a medida que la inclusión de aceite de oliva lampante se incrementó en la dieta. En conclusión, la inclusión de aceite de oliva lampante en dietas de ovejas lactantes aumenta la concentración de ácidos grasos monoinsaturados y disminuye la de los saturados en leche y queso con posibles efectos benéficos sobre la salud humana. PALABRAS CLAVE: Aceite de oliva -Ácidos grasosLeche -Oveja -Queso. SUMMARY Effect of dietary inclusion of lampante olive oil on milk and cheese fatty acid profiles of ewesThe objective of this experiment was to evaluate the effect of a dietary supplementation of lampant olive oil on the fatty aid profiles of the milk and cheese of ewes. Nine lactating ewes were used in a 3 × 3 Latin square design. Dietary treatments were supplemented with 0 (control; T0), 36 (T1) and 88 (T2) g of lampante olive oil/kg of dry matter intake (DM). DM, milk yield and milk composition (fat and protein) were not affected by dietary treatments. Oleic and vaccenic acids gradually increased (P < 0.05) and the saturated FA and atherogenicity index decreased (P < 0.05) in milk and cheese as the concentration of lampante olive oil was increased in dietary rations. Overall, the supplementation of lampante olive oil in the diets of lactating ewes increased monounsaturated FA and decreased saturated FA concentrations in milk and cheese, thus improving their quality from the human health standpoint.

; control, TC) for the first 6 days. From day 7 to 20, the supplement was 25% corn, 25% oats and 50% extruded linseed (500 g ewe -1 milking -1 ) (extruded linseed; TEL). From day 21 to 26, the ewes were fed TC. The saturated FA content in milk was reduced (3.6%), and the monounsaturated, polyunsaturated and n-3 FA (7, 10 and 25%, respectively) were increased when the ewes were supplemented with extruded linseed. A correlation between rumenic acid with vaccenic acid (R 2 =0.68) was found in the milk fat from ewes fed TEL. In cheese obtained from TEL, the contents of n-3 and polyunsaturated FA were increased (21 and 7%, respectively). In conclusion, a supplement of extruded linseed in ewes under grazing conditions could be an alternative lipid source to produce cheese with additional nutritional value. However, the effect of extruded linseed supplementation in ewes under the same conditions with longer experimental periods and a more suitable statistical design must be investigated.