Iván Peña

FEEDING DRY OLIVE CAKE MODIFIES SUBCUTANEOUS FAT COMPOSITION IN LAMBS, NOTING CAKE RESISTANCE TO DEGRADATION AND PEROXIDATION

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.

Feeding extruded linseed to dairy ewes under extensive grazing conditions

The aim of this trial was to evaluate the effect of dietary supplementation of extruded linseed on the milk and cheese fatty acid (FA) profiles of ewes under extensive grazing conditions. Over 26 days, a group of nine lactating ewes (Latxa × Milchaf × Corriedale) in mid-lactation were managed under grazing conditions and given supplements during each manual milking (0830 and 1800 h) of 50% corn and 50% oats (500 g ewe -1 milking -1 ; 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. El objetivo de este ensayo fue evaluar el efecto de suplementar extruido de linaza en el perfil de acidos grasos de leche y queso de ovejas en pastoreo extensivo. Durante 26 dias, un grupo de nueve ovejas lactantes (Latxa × Milchaf × Corriedale) fueron manejadas en pastoreo extensivo y suplementadas durante cada ordeno manual (830 y 1800 h) con 50% maiz + 50% avena (500 g oveja -1 ordeno -1 ) durante los primeros 6 dias (control; TC), de los dias 7 al 20 se suplementaron con 25% maiz + 25% avena + 50% extruido de linaza (500 g/oveja/ordeno) (extruido de linaza; TEL), y finalmente, del dia 21 al 26 las ovejas fueron alimentadas con TC. El contenido de acidos grasos saturados en leche fue reducido (3,6%) mientras que los acido grasos monoinsaturados, polinsaturados y n-3 fueron incrementados (7, 10 y 25%) en aquellas ovejas alimentadas con TEL. Se observo una correlacion de acido rumenico con acido vaccenico (R 2 =0,68) en leche de ovejas alimentadas con TEL. Los quesos elaborados de ovejas alimentadas con TEL, aumentaron su contenido de n-3 y acidos grasos poliinsaturados (21 y 7%). En conclusion, el suplementar ovejas en pastoreo extensivo con extruido de linaza puede ser una alternativa que puede resultar en la elaboracion de quesos con un valor nutricional mas saludable desde el punto de vista humano. Ademas resulta necesario investigar mas sobre el uso del extruido de linaza bajo las mismas condiciones con periodos mas largos de experimentacion usando un diseno estadistico mas apropiado.

Micropropagation of Peatland Bryophytes from Tierra del Fuego

Abstract There exists an increasing pressure on peatland ecosystems in southern South America due to extensive exploitation of Sphagnum and peat. A way to avoid the loss of bryophyte diversity is the establishment of micropropagation protocols. In South America only few studies have assessed the tissue culture of native bryophytes under axenic conditions. The main objective of our work was to assess different conditions to propagate bryophytes, focusing on species from fuegian peatland ecosystems. Four fertile species of mosses (Sphagnum fimbriatum, Conostomum pentastichum, Warnstorfia fluitans, Polytrichastrum longisetum) and one liverwort (Blepharidophyllum densifolium) in vegetative state were collected in bogs of Cape Horn Biosphere Reserve. Cultures were initiated from protonemata obtained after spore germination and from gametophyte fragments. Explants were exposed to four different culture media. Coverage area of the in vitro explants and the number of regenerated shoots were quantitative variables measured after 12 weeks of culture. Overall, small pieces of protonemata (ca 1 mm2) were a suitable explant for the micropropagation of mosses, whereas liverwort regeneration was successfully achieved from apical portions of stems. Media with low mineral concentration or supplemented with a mixture of IBA/BA produced statistically similar effects on the coverage area of mosses. Low mineral medium systematically induced the regeneration of elongated shoots in mosses and liverworts, and the combination of sucrose and IBA/BA systematically induced the production of calli in mosses and liverwort species. This study provides new insights into the propagation of species from poorly known peatland ecosystems of southern South America.