* Manufacturing output up 19.7 pct in Oct from Sept * Manufacturing output up 9.1 pct y/y, beats forecast * Chile copper output up 1.4 pct in Oct to 476,202 tonnes SANTIAGO, Nov 29 (Reuters) - Chilean manufacturing production surged in October, beating expectations on the back of extra working days and a pick-up in already buoyant domestic demand, the government said on Thursday. Manufacturing output leapt a seasonally adjusted 19.7 percent in October from September and grew a stronger-than-forecast 9.1 percent from a year earlier. A Reuters poll saw the index bouncing back in October by 2.7 percent from a year earlier after a sharp fall in September, partly because of a greater number of working days in the month and a low base of comparison. October had five more working days than a holiday-packed September in Chile, fueling the leap in manufacturing. Analyzing the 9.1 percent manufacturing rise in October versus the year-earlier month, the INE statistics agency said: "At the local level, manufacturing production was favored by a positive calendar effect, with three more working days versus October 2011, and also by an increase in domestic and external demand for various products, strongly highlighting increased production of food and beverages." Export-dependent Chile has so far fared better than expected amid fears of a slowdown on the back of slowing demand from top trade partner China. The Andean country's economy expanded 5.7 percent in the third quarter from a year earlier. Chile produced 476,202 tonnes of copper in October, a 1.4 percent rise from the same month a year earlier on improved mineral ore grades and increased production at some of the nation's new mines, the government also said on Thursday. World No.1 copper producer Chile is struggling with stubbornly dwindling ore grades in many of its aging, tired deposits though new and expanded deposits have helped increase output this year. Compared with September, output of the metal grew 2.6 percent. Copper production expanded 3.8 percent to clock 4.46 million tonnes between January and October. Analysts have called into question Chile's aim of producing 5.4 million tonnes of copper this year, deeming it overambitious. A recovery in the world No. 1 copper mine, Escondida, majority owned by BHP Billiton Ltd, as well as higher output from Anglo American Plc's disputed Los Bronces mine are boosting Chile's production. But slipping ore grades and operational problems have dented output. Production at state copper giant Codelco and world's No. 3 copper mine, Collahuasi are down year-on-year.