UPDATE 1-Brazil's JBS Q3 profit drops on lower margins

* JBS Q3 profit down 78 pct from year-ago

* Revenues rose nearly 8 pct to 8.4 bln reais

* Export revenue from Brazil hit by currency appreciation

SAO PAULO, Nov 13 (Reuters) - Brazil's JBS, the world's largest beef producer, posted late on Thursday a 78-percent drop in its third-quarter net earnings as the global financial crisis hit beef prices and cut consumption in key markets.

Net income fell to 151.5 million reais ($87.4 million) from 694 million reais a year earlier, JBS (JBSS3.SA) said in a securities filing.

Revenue, however, rose nearly 8 percent to 8.38 billion reais due mainly to the incorporation of the beef unit of U.S-based Smithfield Foods (SFD.N). This takeover was concluded in 2008.

"Despite relevant efficiency gains in our international operations, the impact of the global crisis over important markets led to a reduction in margins," JBS said.

An 11-percent gain in the Brazilian currency, the real (BRBY), in the third quarter also reduced the company's revenues with exports from Brazil. As the dollar depreciates against the real, so does the local earning power of exports.

Earnings before interest, taxes, depreciation and amortization, a measure of cash flow and operational profitability known as EBITDA, fell 38 percent from a year earlier to 292 million reais.

EBITDA as a percentage of sales, known as the EBITDA margin, fell to 3.5 percent from 6.1 percent a year earlier.

The company has scheduled for Monday a conference call with analysts to give further comments on earnings.

"The weakening of the U.S. dollar and the decline in sales prices had a negative impact on JBS's consolidated EBITDA," it said.

JBS is the leading beef processor in Argentina, Australia, Brazil and Italy and one of the leaders in the United States, after buying last year the beef unit of Smithfield Foods (SFD.N) and beef and pork company Swift & Co.

In September, JBS said it would buy a 64 percent stake in the bankrupt U.S.-based Pilgrim's Pride (PGPDQ.PK) for $800 million. The addition of this company and Brazilian meat company Bertin, announced at the same time, is expected to give JBS about $30 billion in revenue.

JBS USA, a JBS unit which includes operations in the United States and Australia, accounted for 64 percent of the group's revenues while operations in Brazil stood for 17 percent of the global turnover.

($1=1.734 reais) (Reporting by Inae Riveras; Editing by Derek Caney)