Wool production oriented sheep keeping is the most important rural activity in Patagonia, Argentina, followed by goat and at a lower extent cattle production. The existing perception on the smallholder production systems from most decision makers (e.g., policy) is that they are marginal, with low productivity and have negative returns. Since the Argentinean economic scenario has changed drastically in the last decade, the aim of this study was to analyze the economic and productive contribution of different livestock species in smallholdings. The results showed that the post-1990's economic scenario turned most smallholder livestock systems to have positive economic performance, but there were still productive restrictions that limited to fully benefit from these favorable circumstances. Goats were the most profitable livestock due to their higher productive performance, followed by sheep and cattle, with poorer performances. A strong cooperation between the intervention programs and research institutions is recommended to overcome the current production bottlenecks, by focusing on cattle and sheep production systems.

'Mal seco' is an almost invariably fatal disease of horses in Argentina and Chile, which resembles grass sickness, a dysautonomia of horses in Europe. The aetiology of mal seco remains unknown. An attempt to reproduce the disease was made by feeding horses with Festuca argentina, a plant considered to be toxic to animals and which was consistently found in the diet of nine horses suffering from mal seco. Three horses were fed with F argentina ad libitum for 28 days. The plant was infected with an endophytic fungus, whose morphological characteristics were in agreement with descriptions of Acremonium chlamydosporioides. No clinical abnormalities were observed in two of the horses, but one died on the fifth day of the trial after becoming incoordinated, unsteady and ataxic in the fore- and hindlimbs. No gross changes were observed post mortem in any of the horses, with the exception of a small number of Fasciola hepatica in the liver of the horse which died, and a moderate number of Gasterophilus species in the stomach of all three horses. No histopathological changes were observed in any of the organs examined, including several autonomic ganglia, brain including most brain stem nuclei, spinal cord, liver, kidney, stomach and small and large intestine. The results of this study suggest that F argentina is either not implicated in the aetiology of mal seco or produces its effects only when they are triggered by other unknown factors.

PALABRAS CLAVE ADICIONALESInteracciones planta-herbívoro. Terpenos. Calidad de carne. Cordero patagónico. ADDITIONAL KEYWORDSPlant-herbivore interactions. Terpenes. Meat quality. Patagonian lamb. RESUMENEn Patagonia, la ganadería ovina es una de las principales actividades económicas, pero la calidad de la carne de cordero se ve afectada por el sabor desagradable que toma a causa de la ingesta de neneo (Mulinum spinosum (Cav.) Persoon, Apiaceae) que es una planta predominante, y muy accesible para el ganado en primavera-verano. Para detectar los animales afectados antes de su sacrificio, se ensayaron técnicas fitoquímicas en diferentes órganos de la planta y del animal buscando correspondencias. Se estudiaron 2 grupos (uno con neneo como componente de la dieta y el otro no) de 6 animales cada uno a los que se extrajeron muestras de carne, grasa, hígado, orina y sangre. Los compuestos responsables del efecto del neneo pertenecen al grupo de los terpenos/esteroles, el único presente tanto en las flores de neneo, como en la orina de los corderos. Los tejidos animales fueron inadecuados para detectar el neneo siendo la orina el medio más apropiado para ello. Se propone un protocolo con la intención de generar una herramienta que permita desarrollar tecnologías de bajo costo para superar la dificultad, que queda a disposición de investigadores y productores para su puesta a prueba, con el fin de detectar un posible sabor desagradable previo al sacrificio, evitando así la consecuente pérdida económica. SUMMARYIn Patagonia, sheep farming constitutes one of the major economic activities, but the quality of lamb meat is seriously affected by a disagreeable taste found in its tissues, derived from the ovine intake of neneo (Mulinum spinosum (Cav.) Persoon, Apiaceae), predominant in grazing lands easily accessed by sheep during the warm seasons. With the aim of detecting the affected animals before their slaughter, phytochemical testing techniques were applied on different organs of the plant and animal accordingly, in order to identify matches. We studied two groups (one had neneo in their diet while the other did not) of six animals each, of which were extracted samples of meat, fat, liver, urine and blood. The compounds responsible for the effect of neneo belong to the terpene/sterol group, the only present in the flowers of neneo as in the urine of lambs. Various animal tissues were inadequate to detect the presence of neneo in lambs, only urine has been identified as the most suitable to examine the metabolites. A protocol, to experiment with it, was proposed, with the aim of generate a useful tool for the development of low-cost technologies. This protocol is available to researchers and producers to put to the test, with the aim of detecting a disagreeable taste in the animals before their slaughter and avoiding the consequent economic loss. INTRODUCCIÓNLa calidad de la carne es uno de los determinantes para su consumo, y entre los

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