Commodities trader and mining group Glencore Xstrata reported year-on-year production growth across most asset classes in the first quarter.Own-source copper output rose to 382,000 tonnes in the first three months of 2014, up 24% year-on-year, driven by the expansions at Mutanda and Ernest Henry and improved production at Collahuasi and Antamina.Ferrochrome production increased 29% to 335,000 tonnes, following an easy comparator last year when output was limited by an electricity power buyback programme.Own-sourced coal output was up 4% at 34.1m tonnes, enhanced by productivity improvements and growth at expansion projects within its Australian thermal coal operations, as well as the impact of strikes on last year's results.Gross oil output rose 37% to 7.4m barrels, helped by the start of new production from the Alen and Badila fields last summer.However, own-sourced zinc production was down 18% at 306,000 tonnes due to the Perseverance and Brunswick assets reaching the end of their mine lives in June 2013. Excluding their impact, however, zinc production was more or less flat over the year.Glencore said that when compared with the fourth quarter of 2013, own source production of copper, zinc and gold were 10%, 9% and 12% lower, respectively.BC